[09/11] x86: Use dl-symbol-redir-ifunc.h on cpu-tunables
Checks
Context |
Check |
Description |
redhat-pt-bot/TryBot-apply_patch |
success
|
Patch applied to master at the time it was sent
|
linaro-tcwg-bot/tcwg_glibc_check--master-aarch64 |
success
|
Testing passed
|
linaro-tcwg-bot/tcwg_glibc_build--master-arm |
success
|
Testing passed
|
linaro-tcwg-bot/tcwg_glibc_check--master-arm |
success
|
Testing passed
|
linaro-tcwg-bot/tcwg_glibc_build--master-aarch64 |
success
|
Testing passed
|
Commit Message
The dl-symbol-redir-ifunc.h redirects compiler-generated libcalls to
arch-specific memory implementations to avoid ifun calls where it is not
yet possible. The memcmp-isa-default-impl.h aims to fix the same issue
by calling the specific memset implementation directly.
Using the memcmp symbol directly allows the compile to inline the memset
calls (especially because _dl_tunable_set_hwcaps uses constants values),
generating better code.
For i386, _dl_writev with PIE requires to use the old 'int $0x80'
syscall mode because the calling the TLS register (gs) is not yet
initialized.
Checked on x86_64-linux-gnu.
---
.../i686/multiarch/dl-symbol-redir-ifunc.h | 5 +++
.../sysv/linux/i386/dl-writev.h} | 18 ++++-----
sysdeps/x86/cpu-tunables.c | 39 ++++++-------------
.../x86_64/multiarch/dl-symbol-redir-ifunc.h | 15 +++++++
4 files changed, 39 insertions(+), 38 deletions(-)
rename sysdeps/{x86_64/memcmp-isa-default-impl.h => unix/sysv/linux/i386/dl-writev.h} (62%)
Comments
On Tue, Oct 10, 2023 at 1:07 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> The dl-symbol-redir-ifunc.h redirects compiler-generated libcalls to
> arch-specific memory implementations to avoid ifun calls where it is not
> yet possible. The memcmp-isa-default-impl.h aims to fix the same issue
> by calling the specific memset implementation directly.
>
> Using the memcmp symbol directly allows the compile to inline the memset
> calls (especially because _dl_tunable_set_hwcaps uses constants values),
> generating better code.
>
> For i386, _dl_writev with PIE requires to use the old 'int $0x80'
> syscall mode because the calling the TLS register (gs) is not yet
> initialized.
>
> Checked on x86_64-linux-gnu.
> ---
> .../i686/multiarch/dl-symbol-redir-ifunc.h | 5 +++
> .../sysv/linux/i386/dl-writev.h} | 18 ++++-----
> sysdeps/x86/cpu-tunables.c | 39 ++++++-------------
> .../x86_64/multiarch/dl-symbol-redir-ifunc.h | 15 +++++++
> 4 files changed, 39 insertions(+), 38 deletions(-)
> rename sysdeps/{x86_64/memcmp-isa-default-impl.h => unix/sysv/linux/i386/dl-writev.h} (62%)
>
> diff --git a/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
> index dee69d19db..220c586bd2 100644
> --- a/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
> +++ b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
> @@ -19,6 +19,11 @@
> #ifndef _DL_IFUNC_GENERIC_H
> #define _DL_IFUNC_GENERIC_H
>
> +#ifndef SHARED
> +
> asm ("memset = __memset_ia32");
> +asm ("memcmp = __memcmp_ia32");
> +
> +#endif /* SHARED */
>
> #endif
> diff --git a/sysdeps/x86_64/memcmp-isa-default-impl.h b/sysdeps/unix/sysv/linux/i386/dl-writev.h
> similarity index 62%
> rename from sysdeps/x86_64/memcmp-isa-default-impl.h
> rename to sysdeps/unix/sysv/linux/i386/dl-writev.h
> index 0962e83c3d..624d0e46b0 100644
> --- a/sysdeps/x86_64/memcmp-isa-default-impl.h
> +++ b/sysdeps/unix/sysv/linux/i386/dl-writev.h
> @@ -1,5 +1,5 @@
> -/* Set default memcmp impl based on ISA level.
> - Copyright (C) 2022-2023 Free Software Foundation, Inc.
> +/* Message-writing for the dynamic linker. Linux/i386 version.
> + Copyright (C) 2013-2023 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
> @@ -16,13 +16,9 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#include <isa-level.h>
> -#if MINIMUM_X86_ISA_LEVEL == 1 || MINIMUM_X86_ISA_LEVEL == 2
> -# define DEFAULT_MEMCMP __memcmp_sse2
> -#elif MINIMUM_X86_ISA_LEVEL == 3
> -# define DEFAULT_MEMCMP __memcmp_avx2_movbe
> -#elif MINIMUM_X86_ISA_LEVEL == 4
> -# define DEFAULT_MEMCMP __memcmp_evex_movbe
> -#else
> -# error "Unknown default memcmp implementation"
> +#if BUILD_PIE_DEFAULT
> +/* Can't use "call *%gs:SYSINFO_OFFSET" during startup in static PIE. */
> +# define I386_USE_SYSENTER 0
> #endif
> +
> +#include <sysdeps/unix/sysv/linux/dl-writev.h>
> diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
> index 0d4f328585..5697885226 100644
> --- a/sysdeps/x86/cpu-tunables.c
> +++ b/sysdeps/x86/cpu-tunables.c
> @@ -24,24 +24,11 @@
> #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__
> -/* DEFAULT_MEMCMP by sysdeps/x86_64/memcmp-isa-default-impl.h. */
> -# include <sysdeps/x86_64/memcmp-isa-default-impl.h>
> -# else
> -# define DEFAULT_MEMCMP __memcmp_ia32
> -# endif
> -extern __typeof (memcmp) DEFAULT_MEMCMP;
> -#else
> -# define DEFAULT_MEMCMP memcmp
> -#endif
> +#include <dl-symbol-redir-ifunc.h>
>
> #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)) \
> + if (memcmp (f, #name, len) == 0) \
> { \
> CPU_FEATURE_UNSET (cpu_features, name) \
> break; \
> @@ -51,7 +38,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
> which isn't available. */
> #define CHECK_GLIBC_IFUNC_PREFERRED_OFF(f, cpu_features, name, len) \
> _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> - if (!DEFAULT_MEMCMP (f, #name, len)) \
> + if (memcmp (f, #name, len) == 0) \
> { \
> cpu_features->preferred[index_arch_##name] \
> &= ~bit_arch_##name; \
> @@ -62,7 +49,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
> #define CHECK_GLIBC_IFUNC_PREFERRED_BOTH(f, cpu_features, name, \
> disable, len) \
> _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> - if (!DEFAULT_MEMCMP (f, #name, len)) \
> + if (memcmp (f, #name, len) == 0) \
> { \
> if (disable) \
> cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
> @@ -76,7 +63,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
> #define CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH(f, cpu_features, name, \
> need, disable, len) \
> _Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
> - if (!DEFAULT_MEMCMP (f, #name, len)) \
> + if (memcmp (f, #name, len) == 0) \
> { \
> if (disable) \
> cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
> @@ -177,7 +164,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
> 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);
> - if (!DEFAULT_MEMCMP (n, "XSAVEC", 6))
> + if (memcmp (n, "XSAVEC", 6) == 0)
> {
> /* Update xsave_state_size to XSAVE state size. */
> cpu_features->xsave_state_size
> @@ -290,12 +277,11 @@ attribute_hidden
> void
> TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
> {
> - if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
> + if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
> GL(dl_x86_feature_control).ibt = cet_always_on;
> - else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
> + else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
> GL(dl_x86_feature_control).ibt = cet_always_off;
> - else if (DEFAULT_MEMCMP (valp->strval, "permissive",
> - sizeof ("permissive")) == 0)
> + else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
> GL(dl_x86_feature_control).ibt = cet_permissive;
> }
>
> @@ -303,12 +289,11 @@ attribute_hidden
> void
> TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
> {
> - if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
> + if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
> GL(dl_x86_feature_control).shstk = cet_always_on;
> - else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
> + else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
> GL(dl_x86_feature_control).shstk = cet_always_off;
> - else if (DEFAULT_MEMCMP (valp->strval, "permissive",
> - sizeof ("permissive")) == 0)
> + else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
> GL(dl_x86_feature_control).shstk = cet_permissive;
> }
> #endif
> diff --git a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
> index 3fe73ca1c3..c7d8961bb6 100644
> --- a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
> +++ b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
> @@ -19,6 +19,8 @@
> #ifndef _DL_IFUNC_GENERIC_H
> #define _DL_IFUNC_GENERIC_H
>
> +#ifndef SHARED
> +
> #include <isa-level.h>
>
> #if MINIMUM_X86_ISA_LEVEL >= 4
> @@ -31,4 +33,17 @@
>
> asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
>
> +
> +#if MINIMUM_X86_ISA_LEVEL >= 4
> +# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_evex_movbe"
> +#elif MINIMUM_X86_ISA_LEVEL == 3
> +# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_avx2_movbe"
> +#else
> +# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_sse2"
> +#endif
> +
> +asm ("memcmp = " HAVE_MEMCMP_IFUNC_GENERIC);
> +
> +#endif /* SHARED */
> +
> #endif
> --
> 2.34.1
>
LGTM.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
@@ -19,6 +19,11 @@
#ifndef _DL_IFUNC_GENERIC_H
#define _DL_IFUNC_GENERIC_H
+#ifndef SHARED
+
asm ("memset = __memset_ia32");
+asm ("memcmp = __memcmp_ia32");
+
+#endif /* SHARED */
#endif
similarity index 62%
rename from sysdeps/x86_64/memcmp-isa-default-impl.h
rename to sysdeps/unix/sysv/linux/i386/dl-writev.h
@@ -1,5 +1,5 @@
-/* Set default memcmp impl based on ISA level.
- Copyright (C) 2022-2023 Free Software Foundation, Inc.
+/* Message-writing for the dynamic linker. Linux/i386 version.
+ Copyright (C) 2013-2023 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
@@ -16,13 +16,9 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <isa-level.h>
-#if MINIMUM_X86_ISA_LEVEL == 1 || MINIMUM_X86_ISA_LEVEL == 2
-# define DEFAULT_MEMCMP __memcmp_sse2
-#elif MINIMUM_X86_ISA_LEVEL == 3
-# define DEFAULT_MEMCMP __memcmp_avx2_movbe
-#elif MINIMUM_X86_ISA_LEVEL == 4
-# define DEFAULT_MEMCMP __memcmp_evex_movbe
-#else
-# error "Unknown default memcmp implementation"
+#if BUILD_PIE_DEFAULT
+/* Can't use "call *%gs:SYSINFO_OFFSET" during startup in static PIE. */
+# define I386_USE_SYSENTER 0
#endif
+
+#include <sysdeps/unix/sysv/linux/dl-writev.h>
@@ -24,24 +24,11 @@
#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__
-/* DEFAULT_MEMCMP by sysdeps/x86_64/memcmp-isa-default-impl.h. */
-# include <sysdeps/x86_64/memcmp-isa-default-impl.h>
-# else
-# define DEFAULT_MEMCMP __memcmp_ia32
-# endif
-extern __typeof (memcmp) DEFAULT_MEMCMP;
-#else
-# define DEFAULT_MEMCMP memcmp
-#endif
+#include <dl-symbol-redir-ifunc.h>
#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)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
CPU_FEATURE_UNSET (cpu_features, name) \
break; \
@@ -51,7 +38,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
which isn't available. */
#define CHECK_GLIBC_IFUNC_PREFERRED_OFF(f, cpu_features, name, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
cpu_features->preferred[index_arch_##name] \
&= ~bit_arch_##name; \
@@ -62,7 +49,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
#define CHECK_GLIBC_IFUNC_PREFERRED_BOTH(f, cpu_features, name, \
disable, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
if (disable) \
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
@@ -76,7 +63,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
#define CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH(f, cpu_features, name, \
need, disable, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
if (disable) \
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
@@ -177,7 +164,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
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);
- if (!DEFAULT_MEMCMP (n, "XSAVEC", 6))
+ if (memcmp (n, "XSAVEC", 6) == 0)
{
/* Update xsave_state_size to XSAVE state size. */
cpu_features->xsave_state_size
@@ -290,12 +277,11 @@ attribute_hidden
void
TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
{
- if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+ if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
GL(dl_x86_feature_control).ibt = cet_always_on;
- else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+ else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
GL(dl_x86_feature_control).ibt = cet_always_off;
- else if (DEFAULT_MEMCMP (valp->strval, "permissive",
- sizeof ("permissive")) == 0)
+ else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
GL(dl_x86_feature_control).ibt = cet_permissive;
}
@@ -303,12 +289,11 @@ attribute_hidden
void
TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
{
- if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+ if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
GL(dl_x86_feature_control).shstk = cet_always_on;
- else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+ else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
GL(dl_x86_feature_control).shstk = cet_always_off;
- else if (DEFAULT_MEMCMP (valp->strval, "permissive",
- sizeof ("permissive")) == 0)
+ else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
GL(dl_x86_feature_control).shstk = cet_permissive;
}
#endif
@@ -19,6 +19,8 @@
#ifndef _DL_IFUNC_GENERIC_H
#define _DL_IFUNC_GENERIC_H
+#ifndef SHARED
+
#include <isa-level.h>
#if MINIMUM_X86_ISA_LEVEL >= 4
@@ -31,4 +33,17 @@
asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
+
+#if MINIMUM_X86_ISA_LEVEL >= 4
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_evex_movbe"
+#elif MINIMUM_X86_ISA_LEVEL == 3
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_avx2_movbe"
+#else
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_sse2"
+#endif
+
+asm ("memcmp = " HAVE_MEMCMP_IFUNC_GENERIC);
+
+#endif /* SHARED */
+
#endif