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b46d250656
The kernel version check is used to avoid glibc to run on older kernels where some syscall are not available and fallback code are not enabled to handle graciously fail. However, it does not prevent if the kernel does not correctly advertise its version through vDSO note, uname or procfs. Also kernel version checks are sometime not desirable by users, where they want to deploy on different system with different kernel version knowing the minimum set of syscall is always presented on such systems. The kernel version check has been removed along with the LD_ASSUME_KERNEL environment variable. The minimum kernel used to built glibc is still provided through NT_GNU_ABI_TAG ELF note and also printed when libc.so is issued. Checked on x86_64-linux-gnu.
253 lines
8.3 KiB
C
253 lines
8.3 KiB
C
/* Dynamic linker system dependencies for Linux.
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Copyright (C) 1995-2022 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 <_itoa.h>
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#include <assert.h>
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#include <dl-auxv.h>
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#include <dl-osinfo.h>
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#include <dl-parse_auxv.h>
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#include <dl-procinfo.h>
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#include <dl-tunables.h>
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#include <elf.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <ldsodefs.h>
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#include <libc-internal.h>
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#include <libintl.h>
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#include <not-cancel.h>
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#include <stdlib.h>
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#include <string.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/utsname.h>
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#include <tls.h>
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#include <unistd.h>
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#include <dl-machine.h>
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#include <dl-hwcap-check.h>
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#ifdef SHARED
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extern char **_environ attribute_hidden;
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extern char _end[] attribute_hidden;
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/* Protect SUID program against misuse of file descriptors. */
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extern void __libc_check_standard_fds (void);
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int __libc_enable_secure attribute_relro = 0;
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rtld_hidden_data_def (__libc_enable_secure)
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/* This variable contains the lowest stack address ever used. */
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void *__libc_stack_end attribute_relro = NULL;
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rtld_hidden_data_def(__libc_stack_end)
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void *_dl_random attribute_relro = NULL;
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#ifndef DL_STACK_END
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# define DL_STACK_END(cookie) ((void *) (cookie))
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#endif
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/* Arguments passed to dl_main. */
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struct dl_main_arguments
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{
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const ElfW(Phdr) *phdr;
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ElfW(Word) phnum;
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ElfW(Addr) user_entry;
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};
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/* Separate function, so that dl_main can be called without the large
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array on the stack. */
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static void
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_dl_sysdep_parse_arguments (void **start_argptr,
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struct dl_main_arguments *args)
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{
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_dl_argc = (intptr_t) *start_argptr;
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_dl_argv = (char **) (start_argptr + 1); /* Necessary aliasing violation. */
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_environ = _dl_argv + _dl_argc + 1;
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for (char **tmp = _environ; ; ++tmp)
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if (*tmp == NULL)
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{
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/* Another necessary aliasing violation. */
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GLRO(dl_auxv) = (ElfW(auxv_t) *) (tmp + 1);
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break;
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}
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dl_parse_auxv_t auxv_values = { 0, };
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_dl_parse_auxv (GLRO(dl_auxv), auxv_values);
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args->phdr = (const ElfW(Phdr) *) auxv_values[AT_PHDR];
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args->phnum = auxv_values[AT_PHNUM];
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args->user_entry = auxv_values[AT_ENTRY];
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}
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ElfW(Addr)
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_dl_sysdep_start (void **start_argptr,
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void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
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ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
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{
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__libc_stack_end = DL_STACK_END (start_argptr);
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struct dl_main_arguments dl_main_args;
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_dl_sysdep_parse_arguments (start_argptr, &dl_main_args);
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dl_hwcap_check ();
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__tunables_init (_environ);
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/* Initialize DSO sorting algorithm after tunables. */
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_dl_sort_maps_init ();
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__brk (0); /* Initialize the break. */
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#ifdef DL_PLATFORM_INIT
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DL_PLATFORM_INIT;
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#endif
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/* Determine the length of the platform name. */
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if (GLRO(dl_platform) != NULL)
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GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
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if (__sbrk (0) == _end)
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/* The dynamic linker was run as a program, and so the initial break
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starts just after our bss, at &_end. The malloc in dl-minimal.c
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will consume the rest of this page, so tell the kernel to move the
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break up that far. When the user program examines its break, it
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will see this new value and not clobber our data. */
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__sbrk (GLRO(dl_pagesize)
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- ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
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/* If this is a SUID program we make sure that FDs 0, 1, and 2 are
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allocated. If necessary we are doing it ourself. If it is not
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possible we stop the program. */
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if (__builtin_expect (__libc_enable_secure, 0))
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__libc_check_standard_fds ();
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(*dl_main) (dl_main_args.phdr, dl_main_args.phnum,
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&dl_main_args.user_entry, GLRO(dl_auxv));
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return dl_main_args.user_entry;
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}
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void
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_dl_sysdep_start_cleanup (void)
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{
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}
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void
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_dl_show_auxv (void)
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{
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char buf[64];
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ElfW(auxv_t) *av;
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/* Terminate string. */
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buf[63] = '\0';
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/* The following code assumes that the AT_* values are encoded
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starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
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close by (otherwise the array will be too large). In case we have
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to support a platform where these requirements are not fulfilled
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some alternative implementation has to be used. */
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for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
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{
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static const struct
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{
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const char label[22];
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enum { unknown = 0, dec, hex, str, ignore } form : 8;
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} auxvars[] =
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{
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[AT_EXECFD - 2] = { "EXECFD: ", dec },
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[AT_EXECFN - 2] = { "EXECFN: ", str },
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[AT_PHDR - 2] = { "PHDR: 0x", hex },
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[AT_PHENT - 2] = { "PHENT: ", dec },
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[AT_PHNUM - 2] = { "PHNUM: ", dec },
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[AT_PAGESZ - 2] = { "PAGESZ: ", dec },
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[AT_BASE - 2] = { "BASE: 0x", hex },
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[AT_FLAGS - 2] = { "FLAGS: 0x", hex },
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[AT_ENTRY - 2] = { "ENTRY: 0x", hex },
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[AT_NOTELF - 2] = { "NOTELF: ", hex },
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[AT_UID - 2] = { "UID: ", dec },
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[AT_EUID - 2] = { "EUID: ", dec },
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[AT_GID - 2] = { "GID: ", dec },
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[AT_EGID - 2] = { "EGID: ", dec },
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[AT_PLATFORM - 2] = { "PLATFORM: ", str },
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[AT_HWCAP - 2] = { "HWCAP: ", hex },
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[AT_CLKTCK - 2] = { "CLKTCK: ", dec },
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[AT_FPUCW - 2] = { "FPUCW: ", hex },
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[AT_DCACHEBSIZE - 2] = { "DCACHEBSIZE: 0x", hex },
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[AT_ICACHEBSIZE - 2] = { "ICACHEBSIZE: 0x", hex },
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[AT_UCACHEBSIZE - 2] = { "UCACHEBSIZE: 0x", hex },
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[AT_IGNOREPPC - 2] = { "IGNOREPPC", ignore },
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[AT_SECURE - 2] = { "SECURE: ", dec },
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[AT_BASE_PLATFORM - 2] = { "BASE_PLATFORM: ", str },
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[AT_SYSINFO - 2] = { "SYSINFO: 0x", hex },
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[AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex },
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[AT_RANDOM - 2] = { "RANDOM: 0x", hex },
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[AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex },
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[AT_MINSIGSTKSZ - 2] = { "MINSIGSTKSZ: ", dec },
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[AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec },
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[AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex },
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[AT_L1D_CACHESIZE - 2] = { "L1D_CACHESIZE: ", dec },
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[AT_L1D_CACHEGEOMETRY - 2] = { "L1D_CACHEGEOMETRY: 0x", hex },
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[AT_L2_CACHESIZE - 2] = { "L2_CACHESIZE: ", dec },
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[AT_L2_CACHEGEOMETRY - 2] = { "L2_CACHEGEOMETRY: 0x", hex },
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[AT_L3_CACHESIZE - 2] = { "L3_CACHESIZE: ", dec },
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[AT_L3_CACHEGEOMETRY - 2] = { "L3_CACHEGEOMETRY: 0x", hex },
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};
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unsigned int idx = (unsigned int) (av->a_type - 2);
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if ((unsigned int) av->a_type < 2u
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|| (idx < sizeof (auxvars) / sizeof (auxvars[0])
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&& auxvars[idx].form == ignore))
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continue;
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assert (AT_NULL == 0);
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assert (AT_IGNORE == 1);
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/* Some entries are handled in a special way per platform. */
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if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
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continue;
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if (idx < sizeof (auxvars) / sizeof (auxvars[0])
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&& auxvars[idx].form != unknown)
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{
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const char *val = (char *) av->a_un.a_val;
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if (__builtin_expect (auxvars[idx].form, dec) == dec)
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val = _itoa ((unsigned long int) av->a_un.a_val,
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buf + sizeof buf - 1, 10, 0);
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else if (__builtin_expect (auxvars[idx].form, hex) == hex)
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val = _itoa ((unsigned long int) av->a_un.a_val,
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buf + sizeof buf - 1, 16, 0);
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_dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
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continue;
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}
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/* Unknown value: print a generic line. */
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char buf2[17];
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buf2[sizeof (buf2) - 1] = '\0';
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const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
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buf2 + sizeof buf2 - 1, 16, 0);
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const char *val = _itoa ((unsigned long int) av->a_type,
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buf + sizeof buf - 1, 16, 0);
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_dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
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}
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}
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#endif /* SHARED */
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