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84 lines
2.8 KiB
C
84 lines
2.8 KiB
C
/* Emulate AT_MINSIGSTKSZ. Linux/x86 version.
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Copyright (C) 2020-2023 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Emulate AT_MINSIGSTKSZ with XSAVE. */
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static inline void
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dl_check_minsigstacksize (const struct cpu_features *cpu_features)
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{
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/* Return if AT_MINSIGSTKSZ is provide by kernel. */
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if (GLRO(dl_minsigstacksize) != 0)
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return;
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if (cpu_features->basic.max_cpuid >= 0xd
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&& CPU_FEATURES_CPU_P (cpu_features, OSXSAVE))
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{
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/* Emulate AT_MINSIGSTKSZ. In Linux kernel, the signal frame data
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with XSAVE is composed of the following areas and laid out as:
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------------------------------
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| alignment padding |
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------------------------------
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| xsave buffer |
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------------------------------
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| fsave header (32-bit only) |
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------------------------------
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| siginfo + ucontext |
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------------------------------
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*/
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unsigned int sigframe_size;
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#ifdef __x86_64__
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/* NB: sizeof(struct rt_sigframe) + 8-byte return address in Linux
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kernel. */
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sigframe_size = 440 + 8;
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#else
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/* NB: sizeof(struct sigframe_ia32) + sizeof(struct fregs_state)) +
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4-byte return address + 3 * 4-byte arguments in Linux kernel. */
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sigframe_size = 736 + 112 + 4 + 3 * 4;
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#endif
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/* Add 15 bytes to align the stack to 16 bytes. */
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sigframe_size += 15;
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/* Make the space before xsave buffer multiple of 16 bytes. */
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sigframe_size = ALIGN_UP (sigframe_size, 16);
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/* Add (64 - 16)-byte padding to align xsave buffer at 64 bytes. */
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sigframe_size += 64 - 16;
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unsigned int eax, ebx, ecx, edx;
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__cpuid_count (0xd, 0, eax, ebx, ecx, edx);
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/* Add the size of xsave buffer. */
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sigframe_size += ebx;
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/* Add the size of FP_XSTATE_MAGIC2. */
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#define FP_XSTATE_MAGIC2 0x46505845U
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sigframe_size += sizeof (FP_XSTATE_MAGIC2);
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GLRO(dl_minsigstacksize) = sigframe_size;
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}
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else
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{
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/* NB: Default to a constant MINSIGSTKSZ. */
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_Static_assert (__builtin_constant_p (MINSIGSTKSZ),
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"MINSIGSTKSZ is constant");
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GLRO(dl_minsigstacksize) = MINSIGSTKSZ;
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}
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}
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