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c813c1490d
Get the rseq feature size and alignment requirement from the auxiliary vector for use inside the dynamic loader. Use '__rseq_size' directly to store the feature size. If the main thread registration fails or is disabled by tunable, reset the value to 0. This will be used in the TLS block allocator to compute the size and alignment of the rseq area block for the extended ABI support. Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Florian Weimer <fweimer@redhat.com>
76 lines
3 KiB
C
76 lines
3 KiB
C
/* Parse the Linux auxiliary vector.
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Copyright (C) 1995-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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#include <elf.h>
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#include <entry.h>
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#include <fpu_control.h>
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#include <ldsodefs.h>
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#include <link.h>
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#include <rseq-internal.h>
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typedef ElfW(Addr) dl_parse_auxv_t[AT_MINSIGSTKSZ + 1];
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/* Copy the auxiliary vector into AUXV_VALUES and set up GLRO
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variables. */
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static inline
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void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)
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{
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auxv_values[AT_ENTRY] = (ElfW(Addr)) ENTRY_POINT;
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auxv_values[AT_PAGESZ] = EXEC_PAGESIZE;
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auxv_values[AT_FPUCW] = _FPU_DEFAULT;
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/* NB: Default to a constant CONSTANT_MINSIGSTKSZ. */
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_Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),
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"CONSTANT_MINSIGSTKSZ is constant");
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auxv_values[AT_MINSIGSTKSZ] = CONSTANT_MINSIGSTKSZ;
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for (; av->a_type != AT_NULL; av++)
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if (av->a_type <= AT_MINSIGSTKSZ)
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auxv_values[av->a_type] = av->a_un.a_val;
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GLRO(dl_pagesize) = auxv_values[AT_PAGESZ];
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__libc_enable_secure = auxv_values[AT_SECURE];
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GLRO(dl_platform) = (void *) auxv_values[AT_PLATFORM];
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GLRO(dl_hwcap) = auxv_values[AT_HWCAP];
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GLRO(dl_hwcap2) = auxv_values[AT_HWCAP2];
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GLRO(dl_hwcap3) = auxv_values[AT_HWCAP3];
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GLRO(dl_hwcap4) = auxv_values[AT_HWCAP4];
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GLRO(dl_clktck) = auxv_values[AT_CLKTCK];
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GLRO(dl_fpu_control) = auxv_values[AT_FPUCW];
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_dl_random = (void *) auxv_values[AT_RANDOM];
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GLRO(dl_minsigstacksize) = auxv_values[AT_MINSIGSTKSZ];
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GLRO(dl_sysinfo_dso) = (void *) auxv_values[AT_SYSINFO_EHDR];
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#ifdef NEED_DL_SYSINFO
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if (GLRO(dl_sysinfo_dso) != NULL)
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GLRO(dl_sysinfo) = auxv_values[AT_SYSINFO];
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#endif
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/* Get the rseq feature size, with a minimum of RSEQ_AREA_SIZE_INITIAL_USED
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(20) for kernels that don't have AT_RSEQ_FEATURE_SIZE. Limit the feature
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size to RSEQ_AREA_SIZE_MAX_USED (28) which fits the rseq area in 'struct
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pthread' and represents the maximum feature size of currently released
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kernels. Since no kernels currently cross the 32 bytes of the original
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ABI, the semantics of a feature size of 32 or more are still undetermined.
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*/
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_rseq_size = MIN (MAX (auxv_values[AT_RSEQ_FEATURE_SIZE],
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RSEQ_AREA_SIZE_INITIAL_USED),
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RSEQ_AREA_SIZE_MAX_USED);
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_rseq_align = MAX (auxv_values[AT_RSEQ_ALIGN], RSEQ_MIN_ALIGN);
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DL_PLATFORM_AUXV
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}
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