tunables: Add IFUNC selection and cache sizes
Commit Message
On Tue, Jun 20, 2017 at 7:36 AM, Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
> On Tuesday 20 June 2017 07:11 PM, H.J. Lu wrote:
>> Since ifunc and others are handled in the same name space, I have to
>> make non_temporal_threshold, .. as well as ifunc x86 specific. Will it be
>> OK?
>
> I'm going to add ifunc selection for aarch64 soon, so it makes sense to
> have that generic. You could name the arch-specific tunables as
> x86_non_temporal_threshold and so on.
>
This is the patch I am going to check in.
Thanks.
Comments
Fails to build on i586.
https://build.opensuse.org/package/live_build_log/home:Andreas_Schwab:glibc/glibc/f/i586
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/libc.a(dl-sysdep.o): In function `_dl_tunable_set_ifunc':
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:313: undefined reference to `__memcmp_ia32'
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:299: undefined reference to `__memcmp_ia32'
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:292: undefined reference to `__memcmp_ia32'
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:263: undefined reference to `__memcmp_ia32'
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:244: undefined reference to `__memcmp_ia32'
/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/libc.a(dl-sysdep.o):/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:246: more undefined references to `__memcmp_ia32' follow
collect2: error: ld returned 1 exit status
make[2]: *** [../Rules:224: /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/elf/sln] Error 1
Andreas.
On Tuesday 20 June 2017 08:28 PM, H.J. Lu wrote:
>> I'm going to add ifunc selection for aarch64 soon, so it makes sense to
>> have that generic. You could name the arch-specific tunables as
>> x86_non_temporal_threshold and so on.
>>
>
> This is the patch I am going to check in.
I had not actually reviewed the patch, I only pointed out that I was
doing shared work in aarch64 - sorry if that wasn't clear. Now that I
have, it looks like there are some issues. Please fix them in follow-up
patches.
> From f47c947a7e6648e18cb022fa3f7a7fb63cc8c234 Mon Sep 17 00:00:00 2001
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Tue, 23 May 2017 20:22:13 -0700
> Subject: [PATCH] tunables: Add IFUNC selection and cache sizes
>
> The current IFUNC selection is based on microbenchmarks in glibc. It
> should give the best performance for most workloads. But other choices
> may have better performance for a particular workload or on the hardware
> which wasn't available at the selection was made. The environment
> variable, GLIBC_TUNABLES=glibc.tune.ifunc=-xxx,yyy,-zzz...., can be used
> to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy and zzz,
> where the feature name is case-sensitive and has to match the ones in
> cpu-features.h. It can be used by glibc developers to override the
> IFUNC selection to tune for a new processor or improve performance for
> a particular workload. It isn't intended for normal end users.
>
> NOTE: the IFUNC selection may change over time. Please check all
> multiarch implementations when experimenting.
>
> Also, GLIBC_TUNABLES=glibc.tune.x86_non_temporal_threshold=NUMBER is
> provided to set threshold to use non temporal store to NUMBER,
> GLIBC_TUNABLES=glibc.tune.x86_data_cache_size=NUMBER to set data cache
> size, GLIBC_TUNABLES=glibc.tune.x86_shared_cache_size=NUMBER to set
> shared cache size.
>
> 2017-06-15 H.J. Lu <hongjiu.lu@intel.com>
> Erich Elsen <eriche@google.com>
>
> * elf/dl-tunables.list (tune): Add ifunc,
> x86_non_temporal_threshold,
> x86_data_cache_size and x86_shared_cache_size.
> * manual/tunables.texi: Document glibc.tune.ifunc,
> glibc.tune.x86_data_cache_size, glibc.tune.x86_shared_cache_size
> and glibc.tune.x86_non_temporal_threshold.
> * sysdeps/unix/sysv/linux/x86/dl-sysdep.c: New file.
> * sysdeps/x86/cpu-tunables.c: Likewise.
> * sysdeps/x86/cacheinfo.c
> (init_cacheinfo): Check and get data cache size, shared cache
> size and non temporal threshold from cpu_features.
> * sysdeps/x86/cpu-features.c [HAVE_TUNABLES] (TUNABLE_NAMESPACE):
> New.
> [HAVE_TUNABLES] Include <unistd.h>.
> [HAVE_TUNABLES] Include <elf/dl-tunables.h>.
> [HAVE_TUNABLES] (TUNABLE_CALLBACK (set_ifunc)): Likewise.
> [HAVE_TUNABLES] (init_cpu_features): Use TUNABLE_GET to set
> IFUNC selection, data cache size, shared cache size and non
> temporal threshold.
> * sysdeps/x86/cpu-features.h (cpu_features): Add data_cache_size,
> shared_cache_size and non_temporal_threshold.
> ---
> elf/dl-tunables.list | 16 ++
> manual/tunables.texi | 36 ++++
> sysdeps/unix/sysv/linux/x86/dl-sysdep.c | 21 ++
> sysdeps/x86/cacheinfo.c | 10 +-
> sysdeps/x86/cpu-features.c | 19 ++
> sysdeps/x86/cpu-features.h | 8 +
> sysdeps/x86/cpu-tunables.c | 330 ++++++++++++++++++++++++++++++++
> 7 files changed, 439 insertions(+), 1 deletion(-)
> create mode 100644 sysdeps/unix/sysv/linux/x86/dl-sysdep.c
> create mode 100644 sysdeps/x86/cpu-tunables.c
>
> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
> index 41ce9af..3247d49 100644
> --- a/elf/dl-tunables.list
> +++ b/elf/dl-tunables.list
> @@ -82,6 +82,22 @@ glibc {
> type: UINT_64
> env_alias: LD_HWCAP_MASK
> default: HWCAP_IMPORTANT
> + }
> + ifunc {
> + type: STRING
> + security_level: SXID_IGNORE
> + }
> + x86_non_temporal_threshold {
> + type: SIZE_T
> + security_level: SXID_IGNORE
> + }
> + x86_data_cache_size {
> + type: SIZE_T
> + security_level: SXID_IGNORE
> + }
> + x86_shared_cache_size {
> + type: SIZE_T
> + security_level: SXID_IGNORE
> }
Why do you need these to be inherited by children of setuid processes?
If not, then you should remove the SXID_IGNORE and let the default (i.e.
SXID_ERASE) prevail so that setuid processes and their children do not
see these tunables.
Also you've specified these as size_t but the values seem to get stored
in long int. Please fix them.
> }
> }
> diff --git a/manual/tunables.texi b/manual/tunables.texi
> index c9a4cb7..3263f94 100644
> --- a/manual/tunables.texi
> +++ b/manual/tunables.texi
> @@ -198,6 +198,14 @@ is 8 times the number of cores online.
> @cindex hardware capability tunables
> @cindex hwcap tunables
> @cindex tunables, hwcap
> +@cindex ifunc tunables
> +@cindex tunables, ifunc
> +@cindex data_cache_size tunables
> +@cindex tunables, data_cache_size
> +@cindex shared_cache_size tunables
> +@cindex tunables, shared_cache_size
> +@cindex non_temporal_threshold tunables
> +@cindex tunables, non_temporal_threshold
>
> @deftp {Tunable namespace} glibc.tune
> Behavior of @theglibc{} can be tuned to assume specific hardware capabilities
> @@ -213,3 +221,31 @@ extensions available in the processor at runtime for some architectures. The
> @code{glibc.tune.hwcap_mask} tunable allows the user to mask out those
> capabilities at runtime, thus disabling use of those extensions.
> @end deftp
> +
> +@deftp Tunable glibc.tune.ifunc
> +The @code{glibc.tune.ifunc=-xxx,yyy,-zzz...} tunable allows the user to
> +enable CPU/ARCH feature @code{yyy}, disable CPU/ARCH feature @code{xxx}
> +and @code{zzz} where the feature name is case-sensitive and has to match
> +the ones in @code{sysdeps/x86/cpu-features.h}.
I misunderstood that you were using ifunc to specify core names but it
looks like you're also selecting features. The feature selection is
analogous to hwcap_mask in behaviour so you should be calling it
something more appropriate, i.e. 'glibc.tune.hwcaps'. Since other
architectures currently don't need this, you can move it to
sysdeps/x86/dl-tunables.list but keep the name generic since it sounds
like something other architectures may want in future if/when the hwcaps
run out.
For core names add a different tunable called 'glibc.tune.cpu', which
could be in generic since I will also use it for aarch64. Acceptable
values could be listed in a commonly named header like cpu-names.h.
I'll follow your lead in that.
> +
> +This tunable is specific to i386 and x86-64.
> +@end deftp
> +
> +@deftp Tunable glibc.tune.x86_data_cache_size
> +The @code{glibc.tune.x86_data_cache_size} tunable allows the user to set
> +data cache size in bytes for use in memory and string routines.
> +
> +This tunable is specific to i386 and x86-64.
> +@end deftp
> +
> +@deftp Tunable glibc.tune.x86_shared_cache_size
> +The @code{glibc.tune.x86_shared_cache_size} tunable allows the user to
> +set shared cache size in bytes for use in memory and string routines.
> +@end deftp
> +
> +@deftp Tunable glibc.tune.x86_non_temporal_threshold
> +The @code{glibc.tune.x86_non_temporal_threshold} tunable allows the user
> +to set threshold in bytes for non temporal store.
> +
> +This tunable is specific to i386 and x86-64.
> +@end deftp
> diff --git a/sysdeps/unix/sysv/linux/x86/dl-sysdep.c b/sysdeps/unix/sysv/linux/x86/dl-sysdep.c
> new file mode 100644
> index 0000000..64eb0d7
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/x86/dl-sysdep.c
> @@ -0,0 +1,21 @@
> +/* Operating system support for run-time dynamic linker. X86 version.
> + Copyright (C) 2017 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#include <config.h>
> +#include <sysdeps/x86/cpu-tunables.c>
> +#include <sysdeps/unix/sysv/linux/dl-sysdep.c>
> diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
> index 8000fd1..9542dfb 100644
> --- a/sysdeps/x86/cacheinfo.c
> +++ b/sysdeps/x86/cacheinfo.c
> @@ -752,6 +752,9 @@ intel_bug_no_cache_info:
> #endif
> }
>
> + if (cpu_features->data_cache_size != 0)
> + data = cpu_features->data_cache_size;
> +
> if (data > 0)
> {
> __x86_raw_data_cache_size_half = data / 2;
> @@ -762,6 +765,9 @@ intel_bug_no_cache_info:
> __x86_data_cache_size = data;
> }
>
> + if (cpu_features->shared_cache_size != 0)
> + shared = cpu_features->shared_cache_size;
> +
> if (shared > 0)
> {
> __x86_raw_shared_cache_size_half = shared / 2;
> @@ -777,7 +783,9 @@ intel_bug_no_cache_info:
> store becomes faster on a 8-core processor. This is the 3/4 of the
> total shared cache size. */
> __x86_shared_non_temporal_threshold
> - = __x86_shared_cache_size * threads * 3 / 4;
> + = (cpu_features->non_temporal_threshold != 0
> + ? cpu_features->non_temporal_threshold
> + : __x86_shared_cache_size * threads * 3 / 4);
> }
>
> #endif
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index 4288001..76f053a 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -20,6 +20,15 @@
> #include <cpu-features.h>
> #include <dl-hwcap.h>
>
> +#if HAVE_TUNABLES
> +# define TUNABLE_NAMESPACE tune
> +# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
> +# include <elf/dl-tunables.h>
> +
> +extern void TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *)
> + attribute_hidden;
> +#endif
> +
> static void
> get_common_indeces (struct cpu_features *cpu_features,
> unsigned int *family, unsigned int *model,
> @@ -312,6 +321,16 @@ no_cpuid:
> cpu_features->model = model;
> cpu_features->kind = kind;
>
> +#if HAVE_TUNABLES
> + TUNABLE_GET (ifunc, tunable_val_t *, TUNABLE_CALLBACK (set_ifunc));
> + cpu_features->non_temporal_threshold
> + = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL);
> + cpu_features->data_cache_size
> + = TUNABLE_GET (x86_data_cache_size, long int, NULL);
> + cpu_features->shared_cache_size
> + = TUNABLE_GET (x86_shared_cache_size, long int, NULL);
> +#endif
> +
> /* Reuse dl_platform, dl_hwcap and dl_hwcap_mask for x86. */
> GLRO(dl_platform) = NULL;
> GLRO(dl_hwcap) = 0;
> diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
> index f2329ea..fef5e18 100644
> --- a/sysdeps/x86/cpu-features.h
> +++ b/sysdeps/x86/cpu-features.h
> @@ -215,6 +215,14 @@ struct cpu_features
> unsigned int family;
> unsigned int model;
> unsigned int feature[FEATURE_INDEX_MAX];
> + /* Data cache size for use in memory and string routines, typically
> + L1 size. */
> + long int data_cache_size;
> + /* Shared cache size for use in memory and string routines, typically
> + L2 or L3 size. */
> + long int shared_cache_size;
> + /* Threshold to use non temporal store. */
> + long int non_temporal_threshold;
> };
>
> /* Used from outside of glibc to get access to the CPU features
> diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
> new file mode 100644
> index 0000000..9258fb4
> --- /dev/null
> +++ b/sysdeps/x86/cpu-tunables.c
> @@ -0,0 +1,330 @@
> +/* x86 CPU feature tuning.
> + This file is part of the GNU C Library.
> + Copyright (C) 2017 Free Software Foundation, Inc.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#if HAVE_TUNABLES
> +# define TUNABLE_NAMESPACE tune
> +# include <stdbool.h>
> +# include <stdint.h>
> +# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
> +# include <elf/dl-tunables.h>
> +# include <string.h>
> +# include <cpu-features.h>
> +# include <ldsodefs.h>
> +
> +/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
> + since IFUNC must be set up by init_cpu_features. */
> +# if defined USE_MULTIARCH && !defined SHARED
> +# ifdef __x86_64__
> +# define DEFAULT_MEMCMP __memcmp_sse2
> +# define DEFAULT_STRLEN __strlen_sse2
> +# else
> +# define DEFAULT_MEMCMP __memcmp_ia32
> +# define DEFAULT_STRLEN strlen
> +# endif
> +extern __typeof (memcmp) DEFAULT_MEMCMP;
> +extern __typeof (strlen) DEFAULT_STRLEN;
> +# else
> +# define DEFAULT_MEMCMP memcmp
> +# define DEFAULT_STRLEN strlen
> +# endif
Since #name is going to be a constant stirng, you could just use the
is_name from dl-tunables.c. Just pull it out into dl-tunables.h as a
static inline.
> +
> +# define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> + if (!DEFAULT_MEMCMP (f, #name, len)) \
> + { \
> + cpu_features->cpuid[index_cpu_##name].reg_##name \
> + &= ~bit_cpu_##name; \
> + break; \
> + }
> +
> +/* Disable an ARCH feature NAME. We don't enable an ARCH feature which
> + isn't available. */
> +# define CHECK_GLIBC_IFUNC_ARCH_OFF(f, cpu_features, name, len) \
> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> + if (!DEFAULT_MEMCMP (f, #name, len)) > + { \
> + cpu_features->feature[index_arch_##name] \
> + &= ~bit_arch_##name; \
> + break; \
> + }
> +
> +/* Enable/disable an ARCH feature NAME. */
> +# define CHECK_GLIBC_IFUNC_ARCH_BOTH(f, cpu_features, name, disable, \
> + len) \
> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> + if (!DEFAULT_MEMCMP (f, #name, len)) \
> + { \
> + if (disable) \
> + cpu_features->feature[index_arch_##name] \
> + &= ~bit_arch_##name; \
> + else \
> + cpu_features->feature[index_arch_##name] \
> + |= bit_arch_##name; \
> + break; \
> + }
> +
> +/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
> + if the ARCH feature NEED is also enabled. */
> +# define CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH(f, cpu_features, name, \
> + need, disable, len) \
> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> + if (!DEFAULT_MEMCMP (f, #name, len)) \
> + { \
> + if (disable) \
> + cpu_features->feature[index_arch_##name] \
> + &= ~bit_arch_##name; \
> + else if (CPU_FEATURES_ARCH_P (cpu_features, need)) \
> + cpu_features->feature[index_arch_##name] \
> + |= bit_arch_##name; \
> + break; \
> + }
> +
> +/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
> + if the CPU feature NEED is also enabled. */
> +# define CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH(f, cpu_features, name, \
> + need, disable, len) \
> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> + if (!DEFAULT_MEMCMP (f, #name, len)) \
> + { \
> + if (disable) \
> + cpu_features->feature[index_arch_##name] \
> + &= ~bit_arch_##name; \
> + else if (CPU_FEATURES_CPU_P (cpu_features, need)) \
> + cpu_features->feature[index_arch_##name] \
> + |= bit_arch_##name; \
> + break; \
> + }
> +
> +attribute_hidden
> +void
> +TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
It should be set_cpu_features, with the set_cpu_name split out to do
just that one thing and accept only one string value.
> +{
> + /* The current IFUNC selection is based on microbenchmarks in glibc.
> + It should give the best performance for most workloads. But other
> + choices may have better performance for a particular workload or on
> + the hardware which wasn't available when the selection was made.
> + The environment variable, GLIBC_IFUNC=-xxx,yyy,-zzz...., can be
Update comment to reflect the fact that only GLIBC_TUNABLES is present,
not GLIBC_IFUNC.
> + used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy
> + and zzz, where the feature name is case-sensitive and has to match
> + the ones in cpu-features.h. It can be used by glibc developers to
> + tune for a new processor or override the IFUNC selection to improve
> + performance for a particular workload.
> +
> + Since all CPU/ARCH features are hardware optimizations without
> + security implication, except for Prefer_MAP_32BIT_EXEC, which can
> + only be disabled, we check GLIBC_IFUNC for programs, including
> + set*id ones.
> +
> + NOTE: the IFUNC selection may change over time. Please check all
> + multiarch implementations when experimenting. */
> +
> + const char *p = valp->strval;
> + struct cpu_features *cpu_features = &GLRO(dl_x86_cpu_features);
> + const char *end = p + DEFAULT_STRLEN (p);
> + size_t len;
> +
> + do
> + {
> + const char *c, *n;
> + bool disable;
> + size_t nl;
> +
> + for (c = p; *c != ','; c++)
> + if (c >= end)
If you just test on *c == '\0' then you won't need the strlen above.
> + break;
> +
> + len = c - p;
> + disable = *p == '-';
> + if (disable)
> + {
> + n = p + 1;
> + nl = len - 1;
> + }
> + else
> + {
> + n = p;
> + nl = len;
> + }
> + switch (nl)
> + {
> + default:
> + break;
> + case 3:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX, 3);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CX8, 3);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA, 3);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, HTT, 3);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, RTM, 3);
> + }
> + break;
> + case 4:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX2, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI1, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI2, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CMOV, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, ERMS, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA4, 4);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE2, 4);
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I586, 4);
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I686, 4);
> + }
> + break;
> + case 5:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, LZCNT, 5);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, MOVBE, 5);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSSE3, 5);
> + }
> + break;
> + case 6:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
> + }
> + break;
> + case 7:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512F, 7);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, OSXSAVE, 7);
> + }
> + break;
> + case 8:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512CD, 8);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512BW, 8);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512DQ, 8);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512ER, 8);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512PF, 8);
> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512VL, 8);
> + }
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Slow_BSF,
> + disable, 8);
> + break;
> + case 10:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX_Usable,
> + 10);
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA_Usable,
> + 10);
> + }
> + break;
> + case 11:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX2_Usable,
> + 11);
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA4_Usable,
> + 11);
> + }
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Prefer_ERMS,
> + disable, 11);
> + CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH (n, cpu_features,
> + Slow_SSE4_2, SSE4_2,
> + disable, 11);
> + break;
> + case 14:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
> + AVX512F_Usable, 14);
> + }
> + break;
> + case 15:
> + if (disable)
> + {
> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
> + AVX512DQ_Usable, 15);
> + }
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Fast_Rep_String,
> + disable, 15);
> + break;
> + case 16:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
> + (n, cpu_features, Prefer_No_AVX512, AVX512F_Usable,
> + disable, 16);
> + }
> + break;
> + case 18:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
> + Fast_Copy_Backward, disable,
> + 18);
> + }
> + break;
> + case 19:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
> + Fast_Unaligned_Load, disable,
> + 19);
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
> + Fast_Unaligned_Copy, disable,
> + 19);
> + }
> + break;
> + case 20:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
> + (n, cpu_features, Prefer_No_VZEROUPPER, AVX_Usable,
> + disable, 20);
> + }
> + break;
> + case 21:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
> + Prefer_MAP_32BIT_EXEC, disable,
> + 21);
> + }
> + break;
> + case 23:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
> + (n, cpu_features, AVX_Fast_Unaligned_Load, AVX_Usable,
> + disable, 23);
> + }
> + break;
> + case 26:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH
> + (n, cpu_features, Prefer_PMINUB_for_stringop, SSE2,
> + disable, 26);
> + }
> + break;
> + case 27:
> + {
> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
> + Use_dl_runtime_resolve_slow,
> + disable, 27);
> + }
> + break;
> + }
> + p += len + 1;
> + }
> + while (p < end);
Likewise, just check on *p != '\0'.
> +}
> +#endif
>
On Wed, Jun 21, 2017 at 12:28 AM, Andreas Schwab <schwab@suse.de> wrote:
> Fails to build on i586.
>
> https://build.opensuse.org/package/live_build_log/home:Andreas_Schwab:glibc/glibc/f/i586
>
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/libc.a(dl-sysdep.o): In function `_dl_tunable_set_ifunc':
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:313: undefined reference to `__memcmp_ia32'
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:299: undefined reference to `__memcmp_ia32'
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:292: undefined reference to `__memcmp_ia32'
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:263: undefined reference to `__memcmp_ia32'
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:244: undefined reference to `__memcmp_ia32'
> /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/libc.a(dl-sysdep.o):/home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/elf/../sysdeps/x86/cpu-tunables.c:246: more undefined references to `__memcmp_ia32' follow
> collect2: error: ld returned 1 exit status
> make[2]: *** [../Rules:224: /home/abuild/rpmbuild/BUILD/glibc-2.25.90.20170621.g43e0ac24c8/cc-base/elf/sln] Error 1
>
The problem is caused by:
--build=i586-suse-linux --host=i586-suse-linux --enable-multi-arch
which defines:
#define USE_MULTIARCH 1
But i586 doesn't support multiarch. This breaks codes which check
USE_MULTIARCH:
/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
since IFUNC must be set up by init_cpu_features. */
# if defined USE_MULTIARCH && !defined SHARED
# ifdef __x86_64__
# define DEFAULT_MEMCMP __memcmp_sse2
# define DEFAULT_STRLEN __strlen_sse2
# else
# define DEFAULT_MEMCMP __memcmp_ia32
# define DEFAULT_STRLEN strlen
# endif
extern __typeof (memcmp) DEFAULT_MEMCMP;
extern __typeof (strlen) DEFAULT_STRLEN;
# else
# define DEFAULT_MEMCMP memcmp
# define DEFAULT_STRLEN strlen
# endif
The workaround is not configure glibc with --enable-multi-arch when it
isn't supported.
On Wed, Jun 21, 2017 at 1:33 AM, Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
> On Tuesday 20 June 2017 08:28 PM, H.J. Lu wrote:
>>> I'm going to add ifunc selection for aarch64 soon, so it makes sense to
>>> have that generic. You could name the arch-specific tunables as
>>> x86_non_temporal_threshold and so on.
>>>
>>
>> This is the patch I am going to check in.
>
> I had not actually reviewed the patch, I only pointed out that I was
> doing shared work in aarch64 - sorry if that wasn't clear. Now that I
> have, it looks like there are some issues. Please fix them in follow-up
> patches.
>
>> From f47c947a7e6648e18cb022fa3f7a7fb63cc8c234 Mon Sep 17 00:00:00 2001
>> From: "H.J. Lu" <hjl.tools@gmail.com>
>> Date: Tue, 23 May 2017 20:22:13 -0700
>> Subject: [PATCH] tunables: Add IFUNC selection and cache sizes
>>
>> The current IFUNC selection is based on microbenchmarks in glibc. It
>> should give the best performance for most workloads. But other choices
>> may have better performance for a particular workload or on the hardware
>> which wasn't available at the selection was made. The environment
>> variable, GLIBC_TUNABLES=glibc.tune.ifunc=-xxx,yyy,-zzz...., can be used
>> to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy and zzz,
>> where the feature name is case-sensitive and has to match the ones in
>> cpu-features.h. It can be used by glibc developers to override the
>> IFUNC selection to tune for a new processor or improve performance for
>> a particular workload. It isn't intended for normal end users.
>>
>> NOTE: the IFUNC selection may change over time. Please check all
>> multiarch implementations when experimenting.
>>
>> Also, GLIBC_TUNABLES=glibc.tune.x86_non_temporal_threshold=NUMBER is
>> provided to set threshold to use non temporal store to NUMBER,
>> GLIBC_TUNABLES=glibc.tune.x86_data_cache_size=NUMBER to set data cache
>> size, GLIBC_TUNABLES=glibc.tune.x86_shared_cache_size=NUMBER to set
>> shared cache size.
>>
>> 2017-06-15 H.J. Lu <hongjiu.lu@intel.com>
>> Erich Elsen <eriche@google.com>
>>
>> * elf/dl-tunables.list (tune): Add ifunc,
>> x86_non_temporal_threshold,
>> x86_data_cache_size and x86_shared_cache_size.
>> * manual/tunables.texi: Document glibc.tune.ifunc,
>> glibc.tune.x86_data_cache_size, glibc.tune.x86_shared_cache_size
>> and glibc.tune.x86_non_temporal_threshold.
>> * sysdeps/unix/sysv/linux/x86/dl-sysdep.c: New file.
>> * sysdeps/x86/cpu-tunables.c: Likewise.
>> * sysdeps/x86/cacheinfo.c
>> (init_cacheinfo): Check and get data cache size, shared cache
>> size and non temporal threshold from cpu_features.
>> * sysdeps/x86/cpu-features.c [HAVE_TUNABLES] (TUNABLE_NAMESPACE):
>> New.
>> [HAVE_TUNABLES] Include <unistd.h>.
>> [HAVE_TUNABLES] Include <elf/dl-tunables.h>.
>> [HAVE_TUNABLES] (TUNABLE_CALLBACK (set_ifunc)): Likewise.
>> [HAVE_TUNABLES] (init_cpu_features): Use TUNABLE_GET to set
>> IFUNC selection, data cache size, shared cache size and non
>> temporal threshold.
>> * sysdeps/x86/cpu-features.h (cpu_features): Add data_cache_size,
>> shared_cache_size and non_temporal_threshold.
>> ---
>> elf/dl-tunables.list | 16 ++
>> manual/tunables.texi | 36 ++++
>> sysdeps/unix/sysv/linux/x86/dl-sysdep.c | 21 ++
>> sysdeps/x86/cacheinfo.c | 10 +-
>> sysdeps/x86/cpu-features.c | 19 ++
>> sysdeps/x86/cpu-features.h | 8 +
>> sysdeps/x86/cpu-tunables.c | 330 ++++++++++++++++++++++++++++++++
>> 7 files changed, 439 insertions(+), 1 deletion(-)
>> create mode 100644 sysdeps/unix/sysv/linux/x86/dl-sysdep.c
>> create mode 100644 sysdeps/x86/cpu-tunables.c
>>
>> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
>> index 41ce9af..3247d49 100644
>> --- a/elf/dl-tunables.list
>> +++ b/elf/dl-tunables.list
>> @@ -82,6 +82,22 @@ glibc {
>> type: UINT_64
>> env_alias: LD_HWCAP_MASK
>> default: HWCAP_IMPORTANT
>> + }
>> + ifunc {
>> + type: STRING
>> + security_level: SXID_IGNORE
>> + }
>> + x86_non_temporal_threshold {
>> + type: SIZE_T
>> + security_level: SXID_IGNORE
>> + }
>> + x86_data_cache_size {
>> + type: SIZE_T
>> + security_level: SXID_IGNORE
>> + }
>> + x86_shared_cache_size {
>> + type: SIZE_T
>> + security_level: SXID_IGNORE
>> }
>
> Why do you need these to be inherited by children of setuid processes?
> If not, then you should remove the SXID_IGNORE and let the default (i.e.
> SXID_ERASE) prevail so that setuid processes and their children do not
> see these tunables.
I want to be conservative. The default ones should be good for 99.9%
of applications.
> Also you've specified these as size_t but the values seem to get stored
> in long int. Please fix them.
tunables supports:
TUNABLE_TYPE_INT_32,
TUNABLE_TYPE_UINT_64,
TUNABLE_TYPE_SIZE_T,
TUNABLE_TYPE_STRING
There is no long and on x86, long == size_t:
[hjl@gnu-tools-1 tmp]$ cat f.c
#include <unistd.h>
int x [(sizeof (size_t) == sizeof (long)) ? 1 : -1];
[hjl@gnu-tools-1 tmp]$ gcc -S f.c -m64
[hjl@gnu-tools-1 tmp]$ gcc -S f.c -m32
[hjl@gnu-tools-1 tmp]$ gcc -S f.c -mx32
[hjl@gnu-tools-1 tmp]$
>> }
>> }
>> diff --git a/manual/tunables.texi b/manual/tunables.texi
>> index c9a4cb7..3263f94 100644
>> --- a/manual/tunables.texi
>> +++ b/manual/tunables.texi
>> @@ -198,6 +198,14 @@ is 8 times the number of cores online.
>> @cindex hardware capability tunables
>> @cindex hwcap tunables
>> @cindex tunables, hwcap
>> +@cindex ifunc tunables
>> +@cindex tunables, ifunc
>> +@cindex data_cache_size tunables
>> +@cindex tunables, data_cache_size
>> +@cindex shared_cache_size tunables
>> +@cindex tunables, shared_cache_size
>> +@cindex non_temporal_threshold tunables
>> +@cindex tunables, non_temporal_threshold
>>
>> @deftp {Tunable namespace} glibc.tune
>> Behavior of @theglibc{} can be tuned to assume specific hardware capabilities
>> @@ -213,3 +221,31 @@ extensions available in the processor at runtime for some architectures. The
>> @code{glibc.tune.hwcap_mask} tunable allows the user to mask out those
>> capabilities at runtime, thus disabling use of those extensions.
>> @end deftp
>> +
>> +@deftp Tunable glibc.tune.ifunc
>> +The @code{glibc.tune.ifunc=-xxx,yyy,-zzz...} tunable allows the user to
>> +enable CPU/ARCH feature @code{yyy}, disable CPU/ARCH feature @code{xxx}
>> +and @code{zzz} where the feature name is case-sensitive and has to match
>> +the ones in @code{sysdeps/x86/cpu-features.h}.
>
> I misunderstood that you were using ifunc to specify core names but it
> looks like you're also selecting features. The feature selection is
> analogous to hwcap_mask in behaviour so you should be calling it
> something more appropriate, i.e. 'glibc.tune.hwcaps'. Since other
> architectures currently don't need this, you can move it to
> sysdeps/x86/dl-tunables.list but keep the name generic since it sounds
> like something other architectures may want in future if/when the hwcaps
> run out.
I will update it.
> For core names add a different tunable called 'glibc.tune.cpu', which
> could be in generic since I will also use it for aarch64. Acceptable
> values could be listed in a commonly named header like cpu-names.h.
> I'll follow your lead in that.
On x86, there are CPU features, like SSE, AVX, ... and ARCH features,
like slow bsf. X86 tunables allow users to disable AVX and slow bsf.
They don't change any CPU names.
>> +
>> +This tunable is specific to i386 and x86-64.
>> +@end deftp
>> +
>> +@deftp Tunable glibc.tune.x86_data_cache_size
>> +The @code{glibc.tune.x86_data_cache_size} tunable allows the user to set
>> +data cache size in bytes for use in memory and string routines.
>> +
>> +This tunable is specific to i386 and x86-64.
>> +@end deftp
>> +
>> +@deftp Tunable glibc.tune.x86_shared_cache_size
>> +The @code{glibc.tune.x86_shared_cache_size} tunable allows the user to
>> +set shared cache size in bytes for use in memory and string routines.
>> +@end deftp
>> +
>> +@deftp Tunable glibc.tune.x86_non_temporal_threshold
>> +The @code{glibc.tune.x86_non_temporal_threshold} tunable allows the user
>> +to set threshold in bytes for non temporal store.
>> +
>> +This tunable is specific to i386 and x86-64.
>> +@end deftp
>> diff --git a/sysdeps/unix/sysv/linux/x86/dl-sysdep.c b/sysdeps/unix/sysv/linux/x86/dl-sysdep.c
>> new file mode 100644
>> index 0000000..64eb0d7
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/x86/dl-sysdep.c
>> @@ -0,0 +1,21 @@
>> +/* Operating system support for run-time dynamic linker. X86 version.
>> + Copyright (C) 2017 Free Software Foundation, Inc.
>> + This file is part of the GNU C Library.
>> +
>> + The GNU C Library is free software; you can redistribute it and/or
>> + modify it under the terms of the GNU Lesser General Public
>> + License as published by the Free Software Foundation; either
>> + version 2.1 of the License, or (at your option) any later version.
>> +
>> + The GNU C Library is distributed in the hope that it will be useful,
>> + but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> + Lesser General Public License for more details.
>> +
>> + You should have received a copy of the GNU Lesser General Public
>> + License along with the GNU C Library; if not, see
>> + <http://www.gnu.org/licenses/>. */
>> +
>> +#include <config.h>
>> +#include <sysdeps/x86/cpu-tunables.c>
>> +#include <sysdeps/unix/sysv/linux/dl-sysdep.c>
>> diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
>> index 8000fd1..9542dfb 100644
>> --- a/sysdeps/x86/cacheinfo.c
>> +++ b/sysdeps/x86/cacheinfo.c
>> @@ -752,6 +752,9 @@ intel_bug_no_cache_info:
>> #endif
>> }
>>
>> + if (cpu_features->data_cache_size != 0)
>> + data = cpu_features->data_cache_size;
>> +
>> if (data > 0)
>> {
>> __x86_raw_data_cache_size_half = data / 2;
>> @@ -762,6 +765,9 @@ intel_bug_no_cache_info:
>> __x86_data_cache_size = data;
>> }
>>
>> + if (cpu_features->shared_cache_size != 0)
>> + shared = cpu_features->shared_cache_size;
>> +
>> if (shared > 0)
>> {
>> __x86_raw_shared_cache_size_half = shared / 2;
>> @@ -777,7 +783,9 @@ intel_bug_no_cache_info:
>> store becomes faster on a 8-core processor. This is the 3/4 of the
>> total shared cache size. */
>> __x86_shared_non_temporal_threshold
>> - = __x86_shared_cache_size * threads * 3 / 4;
>> + = (cpu_features->non_temporal_threshold != 0
>> + ? cpu_features->non_temporal_threshold
>> + : __x86_shared_cache_size * threads * 3 / 4);
>> }
>>
>> #endif
>> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
>> index 4288001..76f053a 100644
>> --- a/sysdeps/x86/cpu-features.c
>> +++ b/sysdeps/x86/cpu-features.c
>> @@ -20,6 +20,15 @@
>> #include <cpu-features.h>
>> #include <dl-hwcap.h>
>>
>> +#if HAVE_TUNABLES
>> +# define TUNABLE_NAMESPACE tune
>> +# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
>> +# include <elf/dl-tunables.h>
>> +
>> +extern void TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *)
>> + attribute_hidden;
>> +#endif
>> +
>> static void
>> get_common_indeces (struct cpu_features *cpu_features,
>> unsigned int *family, unsigned int *model,
>> @@ -312,6 +321,16 @@ no_cpuid:
>> cpu_features->model = model;
>> cpu_features->kind = kind;
>>
>> +#if HAVE_TUNABLES
>> + TUNABLE_GET (ifunc, tunable_val_t *, TUNABLE_CALLBACK (set_ifunc));
>> + cpu_features->non_temporal_threshold
>> + = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL);
>> + cpu_features->data_cache_size
>> + = TUNABLE_GET (x86_data_cache_size, long int, NULL);
>> + cpu_features->shared_cache_size
>> + = TUNABLE_GET (x86_shared_cache_size, long int, NULL);
>> +#endif
>> +
>> /* Reuse dl_platform, dl_hwcap and dl_hwcap_mask for x86. */
>> GLRO(dl_platform) = NULL;
>> GLRO(dl_hwcap) = 0;
>> diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
>> index f2329ea..fef5e18 100644
>> --- a/sysdeps/x86/cpu-features.h
>> +++ b/sysdeps/x86/cpu-features.h
>> @@ -215,6 +215,14 @@ struct cpu_features
>> unsigned int family;
>> unsigned int model;
>> unsigned int feature[FEATURE_INDEX_MAX];
>> + /* Data cache size for use in memory and string routines, typically
>> + L1 size. */
>> + long int data_cache_size;
>> + /* Shared cache size for use in memory and string routines, typically
>> + L2 or L3 size. */
>> + long int shared_cache_size;
>> + /* Threshold to use non temporal store. */
>> + long int non_temporal_threshold;
>> };
>>
>> /* Used from outside of glibc to get access to the CPU features
>> diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
>> new file mode 100644
>> index 0000000..9258fb4
>> --- /dev/null
>> +++ b/sysdeps/x86/cpu-tunables.c
>> @@ -0,0 +1,330 @@
>> +/* x86 CPU feature tuning.
>> + This file is part of the GNU C Library.
>> + Copyright (C) 2017 Free Software Foundation, Inc.
>> +
>> + The GNU C Library is free software; you can redistribute it and/or
>> + modify it under the terms of the GNU Lesser General Public
>> + License as published by the Free Software Foundation; either
>> + version 2.1 of the License, or (at your option) any later version.
>> +
>> + The GNU C Library is distributed in the hope that it will be useful,
>> + but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> + Lesser General Public License for more details.
>> +
>> + You should have received a copy of the GNU Lesser General Public
>> + License along with the GNU C Library; if not, see
>> + <http://www.gnu.org/licenses/>. */
>> +
>> +#if HAVE_TUNABLES
>> +# define TUNABLE_NAMESPACE tune
>> +# include <stdbool.h>
>> +# include <stdint.h>
>> +# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
>> +# include <elf/dl-tunables.h>
>> +# include <string.h>
>> +# include <cpu-features.h>
>> +# include <ldsodefs.h>
>> +
>> +/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
>> + since IFUNC must be set up by init_cpu_features. */
>> +# if defined USE_MULTIARCH && !defined SHARED
>> +# ifdef __x86_64__
>> +# define DEFAULT_MEMCMP __memcmp_sse2
>> +# define DEFAULT_STRLEN __strlen_sse2
>> +# else
>> +# define DEFAULT_MEMCMP __memcmp_ia32
>> +# define DEFAULT_STRLEN strlen
>> +# endif
>> +extern __typeof (memcmp) DEFAULT_MEMCMP;
>> +extern __typeof (strlen) DEFAULT_STRLEN;
>> +# else
>> +# define DEFAULT_MEMCMP memcmp
>> +# define DEFAULT_STRLEN strlen
>> +# endif
>
> Since #name is going to be a constant stirng, you could just use the
> is_name from dl-tunables.c. Just pull it out into dl-tunables.h as a
> static inline.
memcmp is used elsewhere in ld.so and it is much faster than
is_name in dl-tunables.c. I prefer to keep memcmp here.
>> +
>> +# define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
>> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
>> + if (!DEFAULT_MEMCMP (f, #name, len)) \
>> + { \
>> + cpu_features->cpuid[index_cpu_##name].reg_##name \
>> + &= ~bit_cpu_##name; \
>> + break; \
>> + }
>> +
>> +/* Disable an ARCH feature NAME. We don't enable an ARCH feature which
>> + isn't available. */
>> +# define CHECK_GLIBC_IFUNC_ARCH_OFF(f, cpu_features, name, len) \
>> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
>> + if (!DEFAULT_MEMCMP (f, #name, len)) > + { \
>> + cpu_features->feature[index_arch_##name] \
>> + &= ~bit_arch_##name; \
>> + break; \
>> + }
>> +
>> +/* Enable/disable an ARCH feature NAME. */
>> +# define CHECK_GLIBC_IFUNC_ARCH_BOTH(f, cpu_features, name, disable, \
>> + len) \
>> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
>> + if (!DEFAULT_MEMCMP (f, #name, len)) \
>> + { \
>> + if (disable) \
>> + cpu_features->feature[index_arch_##name] \
>> + &= ~bit_arch_##name; \
>> + else \
>> + cpu_features->feature[index_arch_##name] \
>> + |= bit_arch_##name; \
>> + break; \
>> + }
>> +
>> +/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
>> + if the ARCH feature NEED is also enabled. */
>> +# define CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH(f, cpu_features, name, \
>> + need, disable, len) \
>> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
>> + if (!DEFAULT_MEMCMP (f, #name, len)) \
>> + { \
>> + if (disable) \
>> + cpu_features->feature[index_arch_##name] \
>> + &= ~bit_arch_##name; \
>> + else if (CPU_FEATURES_ARCH_P (cpu_features, need)) \
>> + cpu_features->feature[index_arch_##name] \
>> + |= bit_arch_##name; \
>> + break; \
>> + }
>> +
>> +/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
>> + if the CPU feature NEED is also enabled. */
>> +# define CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH(f, cpu_features, name, \
>> + need, disable, len) \
>> + _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
>> + if (!DEFAULT_MEMCMP (f, #name, len)) \
>> + { \
>> + if (disable) \
>> + cpu_features->feature[index_arch_##name] \
>> + &= ~bit_arch_##name; \
>> + else if (CPU_FEATURES_CPU_P (cpu_features, need)) \
>> + cpu_features->feature[index_arch_##name] \
>> + |= bit_arch_##name; \
>> + break; \
>> + }
>> +
>> +attribute_hidden
>> +void
>> +TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
>
> It should be set_cpu_features, with the set_cpu_name split out to do
> just that one thing and accept only one string value.
We don't set CPU names. We have
#define bit_arch_Fast_Rep_String (1 << 0)
and
#define bit_cpu_AVX (1 << 28)
My tunables just turn them on or off.
>> +{
>> + /* The current IFUNC selection is based on microbenchmarks in glibc.
>> + It should give the best performance for most workloads. But other
>> + choices may have better performance for a particular workload or on
>> + the hardware which wasn't available when the selection was made.
>> + The environment variable, GLIBC_IFUNC=-xxx,yyy,-zzz...., can be
>
> Update comment to reflect the fact that only GLIBC_TUNABLES is present,
> not GLIBC_IFUNC.
I will fix it.
>> + used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy
>> + and zzz, where the feature name is case-sensitive and has to match
>> + the ones in cpu-features.h. It can be used by glibc developers to
>> + tune for a new processor or override the IFUNC selection to improve
>> + performance for a particular workload.
>> +
>> + Since all CPU/ARCH features are hardware optimizations without
>> + security implication, except for Prefer_MAP_32BIT_EXEC, which can
>> + only be disabled, we check GLIBC_IFUNC for programs, including
>> + set*id ones.
>> +
>> + NOTE: the IFUNC selection may change over time. Please check all
>> + multiarch implementations when experimenting. */
>> +
>> + const char *p = valp->strval;
>> + struct cpu_features *cpu_features = &GLRO(dl_x86_cpu_features);
>> + const char *end = p + DEFAULT_STRLEN (p);
>> + size_t len;
>> +
>> + do
>> + {
>> + const char *c, *n;
>> + bool disable;
>> + size_t nl;
>> +
>> + for (c = p; *c != ','; c++)
>> + if (c >= end)
>
> If you just test on *c == '\0' then you won't need the strlen above.
I will take a look.
>> + break;
>> +
>> + len = c - p;
>> + disable = *p == '-';
>> + if (disable)
>> + {
>> + n = p + 1;
>> + nl = len - 1;
>> + }
>> + else
>> + {
>> + n = p;
>> + nl = len;
>> + }
>> + switch (nl)
>> + {
>> + default:
>> + break;
>> + case 3:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX, 3);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CX8, 3);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA, 3);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, HTT, 3);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, RTM, 3);
>> + }
>> + break;
>> + case 4:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX2, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI1, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI2, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CMOV, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, ERMS, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA4, 4);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE2, 4);
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I586, 4);
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I686, 4);
>> + }
>> + break;
>> + case 5:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, LZCNT, 5);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, MOVBE, 5);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSSE3, 5);
>> + }
>> + break;
>> + case 6:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
>> + }
>> + break;
>> + case 7:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512F, 7);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, OSXSAVE, 7);
>> + }
>> + break;
>> + case 8:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512CD, 8);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512BW, 8);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512DQ, 8);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512ER, 8);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512PF, 8);
>> + CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512VL, 8);
>> + }
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Slow_BSF,
>> + disable, 8);
>> + break;
>> + case 10:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX_Usable,
>> + 10);
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA_Usable,
>> + 10);
>> + }
>> + break;
>> + case 11:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX2_Usable,
>> + 11);
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA4_Usable,
>> + 11);
>> + }
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Prefer_ERMS,
>> + disable, 11);
>> + CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH (n, cpu_features,
>> + Slow_SSE4_2, SSE4_2,
>> + disable, 11);
>> + break;
>> + case 14:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
>> + AVX512F_Usable, 14);
>> + }
>> + break;
>> + case 15:
>> + if (disable)
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
>> + AVX512DQ_Usable, 15);
>> + }
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Fast_Rep_String,
>> + disable, 15);
>> + break;
>> + case 16:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
>> + (n, cpu_features, Prefer_No_AVX512, AVX512F_Usable,
>> + disable, 16);
>> + }
>> + break;
>> + case 18:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
>> + Fast_Copy_Backward, disable,
>> + 18);
>> + }
>> + break;
>> + case 19:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
>> + Fast_Unaligned_Load, disable,
>> + 19);
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
>> + Fast_Unaligned_Copy, disable,
>> + 19);
>> + }
>> + break;
>> + case 20:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
>> + (n, cpu_features, Prefer_No_VZEROUPPER, AVX_Usable,
>> + disable, 20);
>> + }
>> + break;
>> + case 21:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
>> + Prefer_MAP_32BIT_EXEC, disable,
>> + 21);
>> + }
>> + break;
>> + case 23:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
>> + (n, cpu_features, AVX_Fast_Unaligned_Load, AVX_Usable,
>> + disable, 23);
>> + }
>> + break;
>> + case 26:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH
>> + (n, cpu_features, Prefer_PMINUB_for_stringop, SSE2,
>> + disable, 26);
>> + }
>> + break;
>> + case 27:
>> + {
>> + CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
>> + Use_dl_runtime_resolve_slow,
>> + disable, 27);
>> + }
>> + break;
>> + }
>> + p += len + 1;
>> + }
>> + while (p < end);
>
> Likewise, just check on *p != '\0'.
I will take a look.
On Wednesday 21 June 2017 05:55 PM, H.J. Lu wrote:
>> Why do you need these to be inherited by children of setuid processes?
>> If not, then you should remove the SXID_IGNORE and let the default (i.e.
>> SXID_ERASE) prevail so that setuid processes and their children do not
>> see these tunables.
>
> I want to be conservative. The default ones should be good for 99.9%
> of applications.
The conservative (in terms of security) should be the default, i.e.
disallow envvars to be read across setxid boundaries. If an escalation
of privileges is required, there should be a specifically stated reason
to do so. The current envvars need a thorough analysis too to figure
out if they need to be read across setxid boundaries.
>> Also you've specified these as size_t but the values seem to get stored
>> in long int. Please fix them.
>
> tunables supports:
>
> TUNABLE_TYPE_INT_32,
> TUNABLE_TYPE_UINT_64,
> TUNABLE_TYPE_SIZE_T,
> TUNABLE_TYPE_STRING
>
> There is no long and on x86, long == size_t:
>
> [hjl@gnu-tools-1 tmp]$ cat f.c
> #include <unistd.h>
>
> int x [(sizeof (size_t) == sizeof (long)) ? 1 : -1];
> [hjl@gnu-tools-1 tmp]$ gcc -S f.c -m64
> [hjl@gnu-tools-1 tmp]$ gcc -S f.c -m32
> [hjl@gnu-tools-1 tmp]$ gcc -S f.c -mx32
> [hjl@gnu-tools-1 tmp]$
Sure, but one is signed and the other isn't, which messes with
validation of the tunable. If long is what you need, you could add
ssize_t, but I don't see why the sizes should be negative. It seems
like instead of making the tunables signed, you should be making the
caches unsigned.
> On x86, there are CPU features, like SSE, AVX, ... and ARCH features,
> like slow bsf. X86 tunables allow users to disable AVX and slow bsf.
> They don't change any CPU names.
Ah OK then you're right, all of those should be hwcaps too and go into
x86 - I thought you were suggesting something like the mtune options,
i.e. corei7. I'll add the glibc.tune.cpu myself.
>> Since #name is going to be a constant stirng, you could just use the
>> is_name from dl-tunables.c. Just pull it out into dl-tunables.h as a
>> static inline.
>
> memcmp is used elsewhere in ld.so and it is much faster than
> is_name in dl-tunables.c. I prefer to keep memcmp here.
Fair enough.
Siddhesh
From f47c947a7e6648e18cb022fa3f7a7fb63cc8c234 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 23 May 2017 20:22:13 -0700
Subject: [PATCH] tunables: Add IFUNC selection and cache sizes
The current IFUNC selection is based on microbenchmarks in glibc. It
should give the best performance for most workloads. But other choices
may have better performance for a particular workload or on the hardware
which wasn't available at the selection was made. The environment
variable, GLIBC_TUNABLES=glibc.tune.ifunc=-xxx,yyy,-zzz...., can be used
to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy and zzz,
where the feature name is case-sensitive and has to match the ones in
cpu-features.h. It can be used by glibc developers to override the
IFUNC selection to tune for a new processor or improve performance for
a particular workload. It isn't intended for normal end users.
NOTE: the IFUNC selection may change over time. Please check all
multiarch implementations when experimenting.
Also, GLIBC_TUNABLES=glibc.tune.x86_non_temporal_threshold=NUMBER is
provided to set threshold to use non temporal store to NUMBER,
GLIBC_TUNABLES=glibc.tune.x86_data_cache_size=NUMBER to set data cache
size, GLIBC_TUNABLES=glibc.tune.x86_shared_cache_size=NUMBER to set
shared cache size.
2017-06-15 H.J. Lu <hongjiu.lu@intel.com>
Erich Elsen <eriche@google.com>
* elf/dl-tunables.list (tune): Add ifunc,
x86_non_temporal_threshold,
x86_data_cache_size and x86_shared_cache_size.
* manual/tunables.texi: Document glibc.tune.ifunc,
glibc.tune.x86_data_cache_size, glibc.tune.x86_shared_cache_size
and glibc.tune.x86_non_temporal_threshold.
* sysdeps/unix/sysv/linux/x86/dl-sysdep.c: New file.
* sysdeps/x86/cpu-tunables.c: Likewise.
* sysdeps/x86/cacheinfo.c
(init_cacheinfo): Check and get data cache size, shared cache
size and non temporal threshold from cpu_features.
* sysdeps/x86/cpu-features.c [HAVE_TUNABLES] (TUNABLE_NAMESPACE):
New.
[HAVE_TUNABLES] Include <unistd.h>.
[HAVE_TUNABLES] Include <elf/dl-tunables.h>.
[HAVE_TUNABLES] (TUNABLE_CALLBACK (set_ifunc)): Likewise.
[HAVE_TUNABLES] (init_cpu_features): Use TUNABLE_GET to set
IFUNC selection, data cache size, shared cache size and non
temporal threshold.
* sysdeps/x86/cpu-features.h (cpu_features): Add data_cache_size,
shared_cache_size and non_temporal_threshold.
---
elf/dl-tunables.list | 16 ++
manual/tunables.texi | 36 ++++
sysdeps/unix/sysv/linux/x86/dl-sysdep.c | 21 ++
sysdeps/x86/cacheinfo.c | 10 +-
sysdeps/x86/cpu-features.c | 19 ++
sysdeps/x86/cpu-features.h | 8 +
sysdeps/x86/cpu-tunables.c | 330 ++++++++++++++++++++++++++++++++
7 files changed, 439 insertions(+), 1 deletion(-)
create mode 100644 sysdeps/unix/sysv/linux/x86/dl-sysdep.c
create mode 100644 sysdeps/x86/cpu-tunables.c
@@ -82,6 +82,22 @@ glibc {
type: UINT_64
env_alias: LD_HWCAP_MASK
default: HWCAP_IMPORTANT
+ }
+ ifunc {
+ type: STRING
+ security_level: SXID_IGNORE
+ }
+ x86_non_temporal_threshold {
+ type: SIZE_T
+ security_level: SXID_IGNORE
+ }
+ x86_data_cache_size {
+ type: SIZE_T
+ security_level: SXID_IGNORE
+ }
+ x86_shared_cache_size {
+ type: SIZE_T
+ security_level: SXID_IGNORE
}
}
}
@@ -198,6 +198,14 @@ is 8 times the number of cores online.
@cindex hardware capability tunables
@cindex hwcap tunables
@cindex tunables, hwcap
+@cindex ifunc tunables
+@cindex tunables, ifunc
+@cindex data_cache_size tunables
+@cindex tunables, data_cache_size
+@cindex shared_cache_size tunables
+@cindex tunables, shared_cache_size
+@cindex non_temporal_threshold tunables
+@cindex tunables, non_temporal_threshold
@deftp {Tunable namespace} glibc.tune
Behavior of @theglibc{} can be tuned to assume specific hardware capabilities
@@ -213,3 +221,31 @@ extensions available in the processor at runtime for some architectures. The
@code{glibc.tune.hwcap_mask} tunable allows the user to mask out those
capabilities at runtime, thus disabling use of those extensions.
@end deftp
+
+@deftp Tunable glibc.tune.ifunc
+The @code{glibc.tune.ifunc=-xxx,yyy,-zzz...} tunable allows the user to
+enable CPU/ARCH feature @code{yyy}, disable CPU/ARCH feature @code{xxx}
+and @code{zzz} where the feature name is case-sensitive and has to match
+the ones in @code{sysdeps/x86/cpu-features.h}.
+
+This tunable is specific to i386 and x86-64.
+@end deftp
+
+@deftp Tunable glibc.tune.x86_data_cache_size
+The @code{glibc.tune.x86_data_cache_size} tunable allows the user to set
+data cache size in bytes for use in memory and string routines.
+
+This tunable is specific to i386 and x86-64.
+@end deftp
+
+@deftp Tunable glibc.tune.x86_shared_cache_size
+The @code{glibc.tune.x86_shared_cache_size} tunable allows the user to
+set shared cache size in bytes for use in memory and string routines.
+@end deftp
+
+@deftp Tunable glibc.tune.x86_non_temporal_threshold
+The @code{glibc.tune.x86_non_temporal_threshold} tunable allows the user
+to set threshold in bytes for non temporal store.
+
+This tunable is specific to i386 and x86-64.
+@end deftp
new file mode 100644
@@ -0,0 +1,21 @@
+/* Operating system support for run-time dynamic linker. X86 version.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include <sysdeps/x86/cpu-tunables.c>
+#include <sysdeps/unix/sysv/linux/dl-sysdep.c>
@@ -752,6 +752,9 @@ intel_bug_no_cache_info:
#endif
}
+ if (cpu_features->data_cache_size != 0)
+ data = cpu_features->data_cache_size;
+
if (data > 0)
{
__x86_raw_data_cache_size_half = data / 2;
@@ -762,6 +765,9 @@ intel_bug_no_cache_info:
__x86_data_cache_size = data;
}
+ if (cpu_features->shared_cache_size != 0)
+ shared = cpu_features->shared_cache_size;
+
if (shared > 0)
{
__x86_raw_shared_cache_size_half = shared / 2;
@@ -777,7 +783,9 @@ intel_bug_no_cache_info:
store becomes faster on a 8-core processor. This is the 3/4 of the
total shared cache size. */
__x86_shared_non_temporal_threshold
- = __x86_shared_cache_size * threads * 3 / 4;
+ = (cpu_features->non_temporal_threshold != 0
+ ? cpu_features->non_temporal_threshold
+ : __x86_shared_cache_size * threads * 3 / 4);
}
#endif
@@ -20,6 +20,15 @@
#include <cpu-features.h>
#include <dl-hwcap.h>
+#if HAVE_TUNABLES
+# define TUNABLE_NAMESPACE tune
+# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
+# include <elf/dl-tunables.h>
+
+extern void TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *)
+ attribute_hidden;
+#endif
+
static void
get_common_indeces (struct cpu_features *cpu_features,
unsigned int *family, unsigned int *model,
@@ -312,6 +321,16 @@ no_cpuid:
cpu_features->model = model;
cpu_features->kind = kind;
+#if HAVE_TUNABLES
+ TUNABLE_GET (ifunc, tunable_val_t *, TUNABLE_CALLBACK (set_ifunc));
+ cpu_features->non_temporal_threshold
+ = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL);
+ cpu_features->data_cache_size
+ = TUNABLE_GET (x86_data_cache_size, long int, NULL);
+ cpu_features->shared_cache_size
+ = TUNABLE_GET (x86_shared_cache_size, long int, NULL);
+#endif
+
/* Reuse dl_platform, dl_hwcap and dl_hwcap_mask for x86. */
GLRO(dl_platform) = NULL;
GLRO(dl_hwcap) = 0;
@@ -215,6 +215,14 @@ struct cpu_features
unsigned int family;
unsigned int model;
unsigned int feature[FEATURE_INDEX_MAX];
+ /* Data cache size for use in memory and string routines, typically
+ L1 size. */
+ long int data_cache_size;
+ /* Shared cache size for use in memory and string routines, typically
+ L2 or L3 size. */
+ long int shared_cache_size;
+ /* Threshold to use non temporal store. */
+ long int non_temporal_threshold;
};
/* Used from outside of glibc to get access to the CPU features
new file mode 100644
@@ -0,0 +1,330 @@
+/* x86 CPU feature tuning.
+ This file is part of the GNU C Library.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#if HAVE_TUNABLES
+# define TUNABLE_NAMESPACE tune
+# include <stdbool.h>
+# include <stdint.h>
+# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
+# include <elf/dl-tunables.h>
+# include <string.h>
+# include <cpu-features.h>
+# include <ldsodefs.h>
+
+/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
+ since IFUNC must be set up by init_cpu_features. */
+# if defined USE_MULTIARCH && !defined SHARED
+# ifdef __x86_64__
+# define DEFAULT_MEMCMP __memcmp_sse2
+# define DEFAULT_STRLEN __strlen_sse2
+# else
+# define DEFAULT_MEMCMP __memcmp_ia32
+# define DEFAULT_STRLEN strlen
+# endif
+extern __typeof (memcmp) DEFAULT_MEMCMP;
+extern __typeof (strlen) DEFAULT_STRLEN;
+# else
+# define DEFAULT_MEMCMP memcmp
+# define DEFAULT_STRLEN strlen
+# endif
+
+# define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
+ _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
+ if (!DEFAULT_MEMCMP (f, #name, len)) \
+ { \
+ cpu_features->cpuid[index_cpu_##name].reg_##name \
+ &= ~bit_cpu_##name; \
+ break; \
+ }
+
+/* Disable an ARCH feature NAME. We don't enable an ARCH feature which
+ isn't available. */
+# define CHECK_GLIBC_IFUNC_ARCH_OFF(f, cpu_features, name, len) \
+ _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
+ if (!DEFAULT_MEMCMP (f, #name, len)) \
+ { \
+ cpu_features->feature[index_arch_##name] \
+ &= ~bit_arch_##name; \
+ break; \
+ }
+
+/* Enable/disable an ARCH feature NAME. */
+# define CHECK_GLIBC_IFUNC_ARCH_BOTH(f, cpu_features, name, disable, \
+ len) \
+ _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
+ if (!DEFAULT_MEMCMP (f, #name, len)) \
+ { \
+ if (disable) \
+ cpu_features->feature[index_arch_##name] \
+ &= ~bit_arch_##name; \
+ else \
+ cpu_features->feature[index_arch_##name] \
+ |= bit_arch_##name; \
+ break; \
+ }
+
+/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
+ if the ARCH feature NEED is also enabled. */
+# define CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH(f, cpu_features, name, \
+ need, disable, len) \
+ _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
+ if (!DEFAULT_MEMCMP (f, #name, len)) \
+ { \
+ if (disable) \
+ cpu_features->feature[index_arch_##name] \
+ &= ~bit_arch_##name; \
+ else if (CPU_FEATURES_ARCH_P (cpu_features, need)) \
+ cpu_features->feature[index_arch_##name] \
+ |= bit_arch_##name; \
+ break; \
+ }
+
+/* Enable/disable an ARCH feature NAME. Enable an ARCH feature only
+ if the CPU feature NEED is also enabled. */
+# define CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH(f, cpu_features, name, \
+ need, disable, len) \
+ _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
+ if (!DEFAULT_MEMCMP (f, #name, len)) \
+ { \
+ if (disable) \
+ cpu_features->feature[index_arch_##name] \
+ &= ~bit_arch_##name; \
+ else if (CPU_FEATURES_CPU_P (cpu_features, need)) \
+ cpu_features->feature[index_arch_##name] \
+ |= bit_arch_##name; \
+ break; \
+ }
+
+attribute_hidden
+void
+TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
+{
+ /* The current IFUNC selection is based on microbenchmarks in glibc.
+ It should give the best performance for most workloads. But other
+ choices may have better performance for a particular workload or on
+ the hardware which wasn't available when the selection was made.
+ The environment variable, GLIBC_IFUNC=-xxx,yyy,-zzz...., can be
+ used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy
+ and zzz, where the feature name is case-sensitive and has to match
+ the ones in cpu-features.h. It can be used by glibc developers to
+ tune for a new processor or override the IFUNC selection to improve
+ performance for a particular workload.
+
+ Since all CPU/ARCH features are hardware optimizations without
+ security implication, except for Prefer_MAP_32BIT_EXEC, which can
+ only be disabled, we check GLIBC_IFUNC for programs, including
+ set*id ones.
+
+ NOTE: the IFUNC selection may change over time. Please check all
+ multiarch implementations when experimenting. */
+
+ const char *p = valp->strval;
+ struct cpu_features *cpu_features = &GLRO(dl_x86_cpu_features);
+ const char *end = p + DEFAULT_STRLEN (p);
+ size_t len;
+
+ do
+ {
+ const char *c, *n;
+ bool disable;
+ size_t nl;
+
+ for (c = p; *c != ','; c++)
+ if (c >= end)
+ break;
+
+ len = c - p;
+ disable = *p == '-';
+ if (disable)
+ {
+ n = p + 1;
+ nl = len - 1;
+ }
+ else
+ {
+ n = p;
+ nl = len;
+ }
+ switch (nl)
+ {
+ default:
+ break;
+ case 3:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX, 3);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CX8, 3);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA, 3);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, HTT, 3);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, RTM, 3);
+ }
+ break;
+ case 4:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX2, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI1, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI2, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CMOV, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, ERMS, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA4, 4);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE2, 4);
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I586, 4);
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, I686, 4);
+ }
+ break;
+ case 5:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, LZCNT, 5);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, MOVBE, 5);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSSE3, 5);
+ }
+ break;
+ case 6:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
+ }
+ break;
+ case 7:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512F, 7);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, OSXSAVE, 7);
+ }
+ break;
+ case 8:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512CD, 8);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512BW, 8);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512DQ, 8);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512ER, 8);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512PF, 8);
+ CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512VL, 8);
+ }
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Slow_BSF,
+ disable, 8);
+ break;
+ case 10:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX_Usable,
+ 10);
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA_Usable,
+ 10);
+ }
+ break;
+ case 11:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, AVX2_Usable,
+ 11);
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features, FMA4_Usable,
+ 11);
+ }
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Prefer_ERMS,
+ disable, 11);
+ CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH (n, cpu_features,
+ Slow_SSE4_2, SSE4_2,
+ disable, 11);
+ break;
+ case 14:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
+ AVX512F_Usable, 14);
+ }
+ break;
+ case 15:
+ if (disable)
+ {
+ CHECK_GLIBC_IFUNC_ARCH_OFF (n, cpu_features,
+ AVX512DQ_Usable, 15);
+ }
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Fast_Rep_String,
+ disable, 15);
+ break;
+ case 16:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
+ (n, cpu_features, Prefer_No_AVX512, AVX512F_Usable,
+ disable, 16);
+ }
+ break;
+ case 18:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
+ Fast_Copy_Backward, disable,
+ 18);
+ }
+ break;
+ case 19:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
+ Fast_Unaligned_Load, disable,
+ 19);
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
+ Fast_Unaligned_Copy, disable,
+ 19);
+ }
+ break;
+ case 20:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
+ (n, cpu_features, Prefer_No_VZEROUPPER, AVX_Usable,
+ disable, 20);
+ }
+ break;
+ case 21:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
+ Prefer_MAP_32BIT_EXEC, disable,
+ 21);
+ }
+ break;
+ case 23:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH
+ (n, cpu_features, AVX_Fast_Unaligned_Load, AVX_Usable,
+ disable, 23);
+ }
+ break;
+ case 26:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH
+ (n, cpu_features, Prefer_PMINUB_for_stringop, SSE2,
+ disable, 26);
+ }
+ break;
+ case 27:
+ {
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features,
+ Use_dl_runtime_resolve_slow,
+ disable, 27);
+ }
+ break;
+ }
+ p += len + 1;
+ }
+ while (p < end);
+}
+#endif
--
2.9.4