diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h | 83 |
1 files changed, 83 insertions, 0 deletions
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 + <https://www.gnu.org/licenses/>. */ + +/* 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; + } +} |