From 7ce7a0e753edd5fbda65cec987d681c65e86960d Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 25 Sep 2020 13:10:08 -0700 Subject: [PATCH] sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack space required in order to gurantee successful, non-nested handling of a single signal whose handler is an empty function, and _SC_SIGSTKSZ which is the suggested minimum number of bytes of stack space required for a signal stack. If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel is composed of the following areas and laid out as: ------------------------------ | alignment padding | ------------------------------ | xsave buffer | ------------------------------ | fsave header (32-bit only) | ------------------------------ | siginfo + ucontext | ------------------------------ Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave header (32-bit only) + size of siginfo and ucontext + alignment padding. If _SC_SIGSTKSZ_SOURCE or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are redefined as /* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */ # undef SIGSTKSZ # define SIGSTKSZ sysconf (_SC_SIGSTKSZ) /* Minimum stack size for a signal handler: SIGSTKSZ. */ # undef MINSIGSTKSZ # define MINSIGSTKSZ SIGSTKSZ Compilation will fail if the source assumes constant MINSIGSTKSZ or SIGSTKSZ. The reason for not simply increasing the kernel's MINSIGSTKSZ #define (apart from the fact that it is rarely used, due to glibc's shadowing definitions) was that userspace binaries will have baked in the old value of the constant and may be making assumptions about it. For example, the type (char [MINSIGSTKSZ]) changes if this #define changes. This could be a problem if an newly built library tries to memcpy() or dump such an object defined by and old binary. Bounds-checking and the stack sizes passed to things like sigaltstack() and makecontext() could similarly go wrong. --- NEWS | 5 ++ bits/confname.h | 8 +- bits/sigstksz.h | 21 +++++ elf/dl-support.c | 5 ++ elf/dl-sysdep.c | 9 ++ include/bits/sigstack.h | 5 ++ include/bits/sigstksz.h | 7 ++ include/features.h | 11 +++ manual/conf.texi | 21 +++++ manual/creature.texi | 6 ++ posix/sysconf.c | 3 + signal/Makefile | 5 +- signal/signal.h | 1 + signal/tst-minsigstksz-5.c | 84 +++++++++++++++++++ sysdeps/generic/ldsodefs.h | 3 + sysdeps/unix/sysv/linux/bits/sigstksz.h | 33 ++++++++ .../unix/sysv/linux/ia64/sysconf-sigstksz.h | 27 ++++++ sysdeps/unix/sysv/linux/sysconf-sigstksz.h | 38 +++++++++ sysdeps/unix/sysv/linux/sysconf.c | 9 ++ .../unix/sysv/linux/x86/dl-minsigstacksize.h | 83 ++++++++++++++++++ .../sysv/linux/x86/include/bits/sigstack.h | 5 ++ sysdeps/x86/cpu-features.c | 3 + sysdeps/x86/dl-minsigstacksize.h | 27 ++++++ 23 files changed, 416 insertions(+), 3 deletions(-) create mode 100644 bits/sigstksz.h create mode 100644 include/bits/sigstack.h create mode 100644 include/bits/sigstksz.h create mode 100644 signal/tst-minsigstksz-5.c create mode 100644 sysdeps/unix/sysv/linux/bits/sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/sysconf-sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h create mode 100644 sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h create mode 100644 sysdeps/x86/dl-minsigstacksize.h diff --git a/NEWS b/NEWS index 0335fb98e5..759a88ce5c 100644 --- a/NEWS +++ b/NEWS @@ -9,6 +9,11 @@ Version 2.33 Major new features: +* Add _SC_MINSIGSTKSZ and _SC_SIGSTKSZ. When _SC_SIGSTKSZ_SOURCE or + _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are no longer + constant on Linux. MINSIGSTKSZ is redefined to sysconf(_SC_MINSIGSTKSZ) + and SIGSTKSZ is redefined to sysconf (_SC_SIGSTKSZ). + * The dynamic linker accepts the --argv0 argument and provides opportunity to change argv[0] string. diff --git a/bits/confname.h b/bits/confname.h index 5dc8215093..451d3eb636 100644 --- a/bits/confname.h +++ b/bits/confname.h @@ -525,8 +525,14 @@ enum _SC_THREAD_ROBUST_PRIO_INHERIT, #define _SC_THREAD_ROBUST_PRIO_INHERIT _SC_THREAD_ROBUST_PRIO_INHERIT - _SC_THREAD_ROBUST_PRIO_PROTECT + _SC_THREAD_ROBUST_PRIO_PROTECT, #define _SC_THREAD_ROBUST_PRIO_PROTECT _SC_THREAD_ROBUST_PRIO_PROTECT + + _SC_MINSIGSTKSZ, +#define _SC_MINSIGSTKSZ _SC_MINSIGSTKSZ + + _SC_SIGSTKSZ +#define _SC_SIGSTKSZ _SC_SIGSTKSZ }; /* Values for the NAME argument to `confstr'. */ diff --git a/bits/sigstksz.h b/bits/sigstksz.h new file mode 100644 index 0000000000..5535d873b5 --- /dev/null +++ b/bits/sigstksz.h @@ -0,0 +1,21 @@ +/* Definition of MINSIGSTKSZ. Generic version. + Copyright (C) 2020 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 + . */ + +#ifndef _SIGNAL_H +# error "Never include directly; use instead." +#endif diff --git a/elf/dl-support.c b/elf/dl-support.c index 15e6d787c9..dd631f50c4 100644 --- a/elf/dl-support.c +++ b/elf/dl-support.c @@ -136,6 +136,8 @@ void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls; size_t _dl_pagesize = EXEC_PAGESIZE; +size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ; + int _dl_inhibit_cache; unsigned int _dl_osversion; @@ -295,6 +297,9 @@ _dl_aux_init (ElfW(auxv_t) *av) case AT_RANDOM: _dl_random = (void *) av->a_un.a_val; break; + case AT_MINSIGSTKSZ: + _dl_minsigstacksize = av->a_un.a_val; + break; DL_PLATFORM_AUXV } if (seen == 0xf) diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c index 854570821c..47400f2937 100644 --- a/elf/dl-sysdep.c +++ b/elf/dl-sysdep.c @@ -117,6 +117,11 @@ _dl_sysdep_start (void **start_argptr, user_entry = (ElfW(Addr)) ENTRY_POINT; GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */ + /* NB: Default to a constant CONSTANT_MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ), + "CONSTANT_MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ; + for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++)) switch (av->a_type) { @@ -181,6 +186,9 @@ _dl_sysdep_start (void **start_argptr, case AT_RANDOM: _dl_random = (void *) av->a_un.a_val; break; + case AT_MINSIGSTKSZ: + GLRO(dl_minsigstacksize) = av->a_un.a_val; + break; DL_PLATFORM_AUXV } @@ -308,6 +316,7 @@ _dl_show_auxv (void) [AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex }, [AT_RANDOM - 2] = { "RANDOM: 0x", hex }, [AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex }, + [AT_MINSIGSTKSZ - 2] = { "MINSIGSTKSZ ", dec }, [AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec }, [AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex }, [AT_L1D_CACHESIZE - 2] = { "L1D_CACHESIZE: ", dec }, diff --git a/include/bits/sigstack.h b/include/bits/sigstack.h new file mode 100644 index 0000000000..eea939f59d --- /dev/null +++ b/include/bits/sigstack.h @@ -0,0 +1,5 @@ +#include_next + +#if !defined _ISOMAC && !defined CONSTANT_MINSIGSTKSZ +# define CONSTANT_MINSIGSTKSZ MINSIGSTKSZ +#endif diff --git a/include/bits/sigstksz.h b/include/bits/sigstksz.h new file mode 100644 index 0000000000..2ca891e918 --- /dev/null +++ b/include/bits/sigstksz.h @@ -0,0 +1,7 @@ +/* NB: Don't define MINSIGSTKSZ nor SIGSTKSZ to sysconf (SC_SIGSTKSZ) for + glibc build. IS_IN can only be used when _ISOMAC isn't defined. */ +#ifdef _ISOMAC +# include_next +#elif IS_IN (libsupport) +# include_next +#endif diff --git a/include/features.h b/include/features.h index f3e62d3362..deaf50928b 100644 --- a/include/features.h +++ b/include/features.h @@ -48,6 +48,8 @@ _LARGEFILE64_SOURCE Additional functionality from LFS for large files. _FILE_OFFSET_BITS=N Select default filesystem interface. _ATFILE_SOURCE Additional *at interfaces. + _SC_SIGSTKSZ_SOURCE Select correct (but non compile-time constant) + MINSIGSTKSZ and SIGSTKSZ. _GNU_SOURCE All of the above, plus GNU extensions. _DEFAULT_SOURCE The default set of features (taking precedence over __STRICT_ANSI__). @@ -94,6 +96,8 @@ __USE_FILE_OFFSET64 Define 64bit interface as default. __USE_MISC Define things from 4.3BSD or System V Unix. __USE_ATFILE Define *at interfaces and AT_* constants for them. + __USE_SC_SIGSTKSZ Define correct (but non compile-time constant) + MINSIGSTKSZ and SIGSTKSZ. __USE_GNU Define GNU extensions. __USE_FORTIFY_LEVEL Additional security measures used, according to level. @@ -137,6 +141,7 @@ #undef __USE_FILE_OFFSET64 #undef __USE_MISC #undef __USE_ATFILE +#undef __USE_SC_SIGSTKSZ #undef __USE_GNU #undef __USE_FORTIFY_LEVEL #undef __KERNEL_STRICT_NAMES @@ -213,6 +218,8 @@ # define _DEFAULT_SOURCE 1 # undef _ATFILE_SOURCE # define _ATFILE_SOURCE 1 +# undef _SC_SIGSTKSZ_SOURCE +# define _SC_SIGSTKSZ_SOURCE 1 #endif /* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined, @@ -388,6 +395,10 @@ # define __USE_ATFILE 1 #endif +#ifdef _SC_SIGSTKSZ_SOURCE +# define __USE_SC_SIGSTKSZ 1 +#endif + #ifdef _GNU_SOURCE # define __USE_GNU 1 #endif diff --git a/manual/conf.texi b/manual/conf.texi index f959b00bb6..ba9847aaa4 100644 --- a/manual/conf.texi +++ b/manual/conf.texi @@ -913,6 +913,27 @@ Inquire about the parameter corresponding to @code{NL_SETMAX}. @item _SC_NL_TEXTMAX @standards{X/Open, unistd.h} Inquire about the parameter corresponding to @code{NL_TEXTMAX}. + +@item _SC_MINSIGSTKSZ +@standards{GNU, unistd.h} +Inquire about the minimum number of bytes of free stack space required +in order to guarantee successful, non-nested handling of a single signal +whose handler is an empty function. + +@item _SC_SIGSTKSZ +@standards{GNU, unistd.h} +Inquire about the suggested minimum number of bytes of stack space +required for a signal stack. + +This is not guaranteed to be enough for any specific purpose other than +the invocation of a single, non-nested, empty handler, but nonetheless +should be enough for basic scenarios involving simple signal handlers +and very low levels of signal nesting (say, 2 or 3 levels at the very +most). + +This value is provided for developer convenience and to ease migration +from the legacy @code{SIGSTKSZ} constant. Programs requiring stronger +guarantees should avoid using it if at all possible. @end vtable @node Examples of Sysconf diff --git a/manual/creature.texi b/manual/creature.texi index be5050468b..8fef4150fa 100644 --- a/manual/creature.texi +++ b/manual/creature.texi @@ -257,6 +257,12 @@ various library functions. If defined to @math{2}, even stricter checks are applied. @end defvr +@defvr Macro _SC_SIGSTKSZ_SOURCE +@standards{GNU, (none)} +If this macro is defined, correct (but non compile-time constant) +MINSIGSTKSZ and SIGSTKSZ are defined. +@end defvr + @defvr Macro _REENTRANT @defvrx Macro _THREAD_SAFE @standards{Obsolete, (none)} diff --git a/posix/sysconf.c b/posix/sysconf.c index ba303384c1..ca7833e6c4 100644 --- a/posix/sysconf.c +++ b/posix/sysconf.c @@ -266,6 +266,9 @@ __sysconf (int name) case _SC_XOPEN_REALTIME: case _SC_XOPEN_REALTIME_THREADS: + case _SC_MINSIGSTKSZ: + case _SC_SIGSTKSZ: + break; } diff --git a/signal/Makefile b/signal/Makefile index 2ec3ddd74f..641d30582d 100644 --- a/signal/Makefile +++ b/signal/Makefile @@ -31,7 +31,8 @@ headers := signal.h sys/signal.h \ bits/types/sigevent_t.h bits/types/siginfo_t.h \ bits/types/sigset_t.h bits/types/sigval_t.h \ bits/types/stack_t.h bits/types/struct_sigstack.h \ - bits/types/__sigval_t.h bits/signal_ext.h + bits/types/__sigval_t.h bits/signal_ext.h \ + bits/sigstksz.h routines := signal raise killpg \ sigaction sigprocmask kill \ @@ -48,7 +49,7 @@ routines := signal raise killpg \ tests := tst-signal tst-sigset tst-sigsimple tst-raise tst-sigset2 \ tst-sigwait-eintr tst-sigaction \ tst-minsigstksz-1 tst-minsigstksz-2 tst-minsigstksz-3 \ - tst-minsigstksz-3a tst-minsigstksz-4 \ + tst-minsigstksz-3a tst-minsigstksz-4 tst-minsigstksz-5 \ tst-sigisemptyset include ../Rules diff --git a/signal/signal.h b/signal/signal.h index effe3d698f..0311eb2a66 100644 --- a/signal/signal.h +++ b/signal/signal.h @@ -312,6 +312,7 @@ extern int siginterrupt (int __sig, int __interrupt) __THROW __attribute_deprecated_msg__ ("Use sigaction with SA_RESTART instead"); # include +# include # include /* Alternate signal handler stack interface. diff --git a/signal/tst-minsigstksz-5.c b/signal/tst-minsigstksz-5.c new file mode 100644 index 0000000000..d657d2f4e6 --- /dev/null +++ b/signal/tst-minsigstksz-5.c @@ -0,0 +1,84 @@ +/* Test of signal delivery on an alternate stack with MINSIGSTKSZ size. + Copyright (C) 2020 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 + . */ + +#include +#include +#include +#include +#include +#include + +static volatile sig_atomic_t handler_run; + +static void +handler (int signo) +{ + /* Clear a bit of on-stack memory. */ + volatile char buffer[256]; + for (size_t i = 0; i < sizeof (buffer); ++i) + buffer[i] = 0; + handler_run = 1; +} + +int +do_test (void) +{ + size_t stack_buffer_size = 64 * 1024 * 1024; + void *stack_buffer = xmalloc (stack_buffer_size); + void *stack_end = stack_buffer + stack_buffer_size; + memset (stack_buffer, 0xCC, stack_buffer_size); + + void *stack_bottom = stack_buffer + (stack_buffer_size + MINSIGSTKSZ) / 2; + void *stack_top = stack_bottom + MINSIGSTKSZ; + stack_t stack = + { + .ss_sp = stack_bottom, + .ss_size = MINSIGSTKSZ, + }; + if (sigaltstack (&stack, NULL) < 0) + FAIL_RET ("sigaltstack: %m\n"); + + struct sigaction act = + { + .sa_handler = handler, + .sa_flags = SA_ONSTACK, + }; + if (sigaction (SIGUSR1, &act, NULL) < 0) + FAIL_RET ("sigaction: %m\n"); + + if (kill (getpid (), SIGUSR1) < 0) + FAIL_RET ("kill: %m\n"); + + if (handler_run != 1) + FAIL_RET ("handler did not run\n"); + + for (void *p = stack_buffer; p < stack_bottom; ++p) + if (*(unsigned char *) p != 0xCC) + FAIL_RET ("changed byte %ld bytes below configured stack\n", + (long) (stack_bottom - p)); + for (void *p = stack_top; p < stack_end; ++p) + if (*(unsigned char *) p != 0xCC) + FAIL_RET ("changed byte %ld bytes above configured stack\n", + (long) (p - stack_top)); + + free (stack_buffer); + + return 0; +} + +#include diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index b1da03cafe..38093e2b8a 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -536,6 +536,9 @@ struct rtld_global_ro /* Cached value of `getpagesize ()'. */ EXTERN size_t _dl_pagesize; + /* Cached value of `sysconf (_SC_MINSIGSTKSZ)'. */ + EXTERN size_t _dl_minsigstacksize; + /* Do we read from ld.so.cache? */ EXTERN int _dl_inhibit_cache; diff --git a/sysdeps/unix/sysv/linux/bits/sigstksz.h b/sysdeps/unix/sysv/linux/bits/sigstksz.h new file mode 100644 index 0000000000..926508f2b4 --- /dev/null +++ b/sysdeps/unix/sysv/linux/bits/sigstksz.h @@ -0,0 +1,33 @@ +/* Definition of MINSIGSTKSZ and SIGSTKSZ. Linux version. + Copyright (C) 2020 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 + . */ + +#ifndef _SIGNAL_H +# error "Never include directly; use instead." +#endif + +#if defined __USE_SC_SIGSTKSZ && __USE_SC_SIGSTKSZ +# include + +/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */ +# undef SIGSTKSZ +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ) + +/* Minimum stack size for a signal handler: SIGSTKSZ. */ +# undef MINSIGSTKSZ +# define MINSIGSTKSZ SIGSTKSZ +#endif diff --git a/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h b/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h new file mode 100644 index 0000000000..7e5ceba151 --- /dev/null +++ b/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h @@ -0,0 +1,27 @@ +/* sysconf_sigstksz (). Linux/ia64 version. + Copyright (C) 2020 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 + . */ + +/* Return sysconf (_SC_SIGSTKSZ). */ + +static long int +sysconf_sigstksz (void) +{ + _Static_assert (__builtin_constant_p (SIGSTKSZ), + "SIGSTKSZ is constant"); + return SIGSTKSZ; +} diff --git a/sysdeps/unix/sysv/linux/sysconf-sigstksz.h b/sysdeps/unix/sysv/linux/sysconf-sigstksz.h new file mode 100644 index 0000000000..64d450b22c --- /dev/null +++ b/sysdeps/unix/sysv/linux/sysconf-sigstksz.h @@ -0,0 +1,38 @@ +/* sysconf_sigstksz (). Linux version. + Copyright (C) 2020 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 + . */ + +/* Return sysconf (_SC_SIGSTKSZ). */ + +static long int +sysconf_sigstksz (void) +{ + long int minsigstacksize = GLRO(dl_minsigstacksize); + assert (minsigstacksize != 0); + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + if (minsigstacksize < MINSIGSTKSZ) + minsigstacksize = MINSIGSTKSZ; + /* MAX (MINSIGSTKSZ, sysconf (_SC_MINSIGSTKSZ)) * 4. */ + long int sigstacksize = minsigstacksize * 4; + /* Return MAX (SIGSTKSZ, sigstacksize). */ + _Static_assert (__builtin_constant_p (SIGSTKSZ), + "SIGSTKSZ is constant"); + if (sigstacksize < SIGSTKSZ) + sigstacksize = SIGSTKSZ; + return sigstacksize; +} diff --git a/sysdeps/unix/sysv/linux/sysconf.c b/sysdeps/unix/sysv/linux/sysconf.c index 9c5a4cb1a4..22eeac50ca 100644 --- a/sysdeps/unix/sysv/linux/sysconf.c +++ b/sysdeps/unix/sysv/linux/sysconf.c @@ -16,6 +16,7 @@ License along with the GNU C Library; if not, see . */ +#include #include #include #include @@ -26,6 +27,7 @@ #include #include #include +#include /* Legacy value of ARG_MAX. The macro is now not defined since the actual value varies based on the stack size. */ @@ -75,6 +77,13 @@ __sysconf (int name) } break; + case _SC_MINSIGSTKSZ: + assert (GLRO(dl_minsigstacksize) != 0); + return GLRO(dl_minsigstacksize); + + case _SC_SIGSTKSZ: + return sysconf_sigstksz (); + default: break; } diff --git a/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h b/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h new file mode 100644 index 0000000000..6088bbc99e --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h @@ -0,0 +1,83 @@ +/* Emulate AT_MINSIGSTKSZ. Linux/x86 version. + Copyright (C) 2020 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 + . */ + +/* Emulate AT_MINSIGSTKSZ with XSAVE. */ + +static inline void +dl_check_minsigstacksize (const struct cpu_features *cpu_features) +{ + /* Return if AT_MINSIGSTKSZ is provide by kernel. */ + if (GLRO(dl_minsigstacksize) != 0) + return; + + if (cpu_features->basic.max_cpuid >= 0xd + && CPU_FEATURES_CPU_P (cpu_features, OSXSAVE)) + { + /* Emulate AT_MINSIGSTKSZ. In Linux kernel, the signal frame data + with XSAVE is composed of the following areas and laid out as: + ------------------------------ + | alignment padding | + ------------------------------ + | xsave buffer | + ------------------------------ + | fsave header (32-bit only) | + ------------------------------ + | siginfo + ucontext | + ------------------------------ + */ + + unsigned int sigframe_size; + +#ifdef __x86_64__ + /* NB: sizeof(struct rt_sigframe) + 8-byte return address in Linux + kernel. */ + sigframe_size = 440 + 8; +#else + /* NB: sizeof(struct sigframe_ia32) + sizeof(struct fregs_state)) + + 4-byte return address + 3 * 4-byte arguments in Linux kernel. */ + sigframe_size = 736 + 112 + 4 + 3 * 4; +#endif + + /* Add 15 bytes to align the stack to 16 bytes. */ + sigframe_size += 15; + + /* Make the space before xsave buffer multiple of 16 bytes. */ + sigframe_size = ALIGN_UP (sigframe_size, 16); + + /* Add (64 - 16)-byte padding to align xsave buffer at 64 bytes. */ + sigframe_size += 64 - 16; + + unsigned int eax, ebx, ecx, edx; + __cpuid_count (0xd, 0, eax, ebx, ecx, edx); + + /* Add the size of xsave buffer. */ + sigframe_size += ebx; + + /* Add the size of FP_XSTATE_MAGIC2. */ +#define FP_XSTATE_MAGIC2 0x46505845U + sigframe_size += sizeof (FP_XSTATE_MAGIC2); + + GLRO(dl_minsigstacksize) = sigframe_size; + } + else + { + /* NB: Default to a constant MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = MINSIGSTKSZ; + } +} diff --git a/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h b/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h new file mode 100644 index 0000000000..208754c497 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h @@ -0,0 +1,5 @@ +#include_next + +#ifndef _ISOMAC +# define CONSTANT_MINSIGSTKSZ 0 +#endif diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index f26deba38d..bef6084f5e 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -19,6 +19,7 @@ #include #include #include +#include #if IS_IN (libc) && !defined SHARED # include # include @@ -367,6 +368,8 @@ get_common_indices (struct cpu_features *cpu_features, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.ebx, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.ecx, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.edx); + + dl_check_minsigstacksize (cpu_features); } _Static_assert (((index_arch_Fast_Unaligned_Load diff --git a/sysdeps/x86/dl-minsigstacksize.h b/sysdeps/x86/dl-minsigstacksize.h new file mode 100644 index 0000000000..959871c970 --- /dev/null +++ b/sysdeps/x86/dl-minsigstacksize.h @@ -0,0 +1,27 @@ +/* Emulate AT_MINSIGSTKSZ. Generic x86 version. + Copyright (C) 2020 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 + . */ + +/* Emulate AT_MINSIGSTKSZ with XSAVE. */ + +static inline void +dl_check_minsigstacksize (const struct cpu_features *cpu_features) +{ + /* NB: Default to a constant MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = MINSIGSTKSZ; +} -- 2.28.0