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440 lines
13 KiB
440 lines
13 KiB
2 years ago
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commit ff900fad89df7fa12750c018993a12cc02474646
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Mon Feb 28 11:50:41 2022 +0100
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Linux: Consolidate auxiliary vector parsing (redo)
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And optimize it slightly.
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This is commit 8c8510ab2790039e58995ef3a22309582413d3ff revised.
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In _dl_aux_init in elf/dl-support.c, use an explicit loop
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and -fno-tree-loop-distribute-patterns to avoid memset.
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Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
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(cherry picked from commit 73fc4e28b9464f0e13edc719a5372839970e7ddb)
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diff --git a/elf/Makefile b/elf/Makefile
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index c89a6a58690646ee..6423ebbdd7708a14 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -148,6 +148,11 @@ ifeq (yes,$(have-loop-to-function))
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CFLAGS-rtld.c += -fno-tree-loop-distribute-patterns
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endif
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+ifeq (yes,$(have-loop-to-function))
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+# Likewise, during static library startup, memset is not yet available.
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+CFLAGS-dl-support.c = -fno-tree-loop-distribute-patterns
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+endif
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+
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# Compile rtld itself without stack protection.
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# Also compile all routines in the static library that are elided from
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# the shared libc because they are in libc.a in the same way.
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diff --git a/elf/dl-support.c b/elf/dl-support.c
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index f29dc965f4d10648..a2e45e7b14e3a6b9 100644
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--- a/elf/dl-support.c
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+++ b/elf/dl-support.c
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@@ -43,6 +43,7 @@
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#include <dl-vdso.h>
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#include <dl-vdso-setup.h>
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#include <dl-auxv.h>
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+#include <array_length.h>
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extern char *__progname;
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char **_dl_argv = &__progname; /* This is checked for some error messages. */
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@@ -241,93 +242,25 @@ __rtld_lock_define_initialized_recursive (, _dl_load_tls_lock)
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#ifdef HAVE_AUX_VECTOR
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+#include <dl-parse_auxv.h>
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+
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int _dl_clktck;
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void
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_dl_aux_init (ElfW(auxv_t) *av)
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{
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- int seen = 0;
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- uid_t uid = 0;
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- gid_t gid = 0;
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-
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#ifdef NEED_DL_SYSINFO
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/* NB: Avoid RELATIVE relocation in static PIE. */
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GL(dl_sysinfo) = DL_SYSINFO_DEFAULT;
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#endif
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_dl_auxv = av;
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- for (; av->a_type != AT_NULL; ++av)
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- switch (av->a_type)
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- {
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- case AT_PAGESZ:
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- if (av->a_un.a_val != 0)
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- GLRO(dl_pagesize) = av->a_un.a_val;
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- break;
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- case AT_CLKTCK:
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- GLRO(dl_clktck) = av->a_un.a_val;
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- break;
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- case AT_PHDR:
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- GL(dl_phdr) = (const void *) av->a_un.a_val;
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- break;
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- case AT_PHNUM:
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- GL(dl_phnum) = av->a_un.a_val;
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- break;
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- case AT_PLATFORM:
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- GLRO(dl_platform) = (void *) av->a_un.a_val;
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- break;
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- case AT_HWCAP:
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- GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
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- break;
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- case AT_HWCAP2:
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- GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
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- break;
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- case AT_FPUCW:
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- GLRO(dl_fpu_control) = av->a_un.a_val;
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- break;
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-#ifdef NEED_DL_SYSINFO
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- case AT_SYSINFO:
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- GL(dl_sysinfo) = av->a_un.a_val;
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- break;
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-#endif
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-#ifdef NEED_DL_SYSINFO_DSO
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- case AT_SYSINFO_EHDR:
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- GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
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- break;
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-#endif
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- case AT_UID:
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- uid ^= av->a_un.a_val;
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- seen |= 1;
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- break;
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- case AT_EUID:
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- uid ^= av->a_un.a_val;
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- seen |= 2;
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- break;
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- case AT_GID:
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- gid ^= av->a_un.a_val;
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- seen |= 4;
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- break;
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- case AT_EGID:
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- gid ^= av->a_un.a_val;
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- seen |= 8;
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- break;
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- case AT_SECURE:
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- seen = -1;
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- __libc_enable_secure = av->a_un.a_val;
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- __libc_enable_secure_decided = 1;
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- break;
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- case AT_RANDOM:
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- _dl_random = (void *) av->a_un.a_val;
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- break;
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- case AT_MINSIGSTKSZ:
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- _dl_minsigstacksize = av->a_un.a_val;
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- break;
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- DL_PLATFORM_AUXV
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- }
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- if (seen == 0xf)
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- {
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- __libc_enable_secure = uid != 0 || gid != 0;
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- __libc_enable_secure_decided = 1;
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- }
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+ dl_parse_auxv_t auxv_values;
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+ /* Use an explicit initialization loop here because memset may not
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+ be available yet. */
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+ for (int i = 0; i < array_length (auxv_values); ++i)
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+ auxv_values[i] = 0;
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+ _dl_parse_auxv (av, auxv_values);
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}
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#endif
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diff --git a/sysdeps/unix/sysv/linux/alpha/dl-auxv.h b/sysdeps/unix/sysv/linux/alpha/dl-auxv.h
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index 1aa9dca80d189ebe..8c99e776a0af9cef 100644
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--- a/sysdeps/unix/sysv/linux/alpha/dl-auxv.h
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+++ b/sysdeps/unix/sysv/linux/alpha/dl-auxv.h
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@@ -20,16 +20,8 @@
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extern long __libc_alpha_cache_shape[4];
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-#define DL_PLATFORM_AUXV \
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- case AT_L1I_CACHESHAPE: \
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- __libc_alpha_cache_shape[0] = av->a_un.a_val; \
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- break; \
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- case AT_L1D_CACHESHAPE: \
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- __libc_alpha_cache_shape[1] = av->a_un.a_val; \
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- break; \
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- case AT_L2_CACHESHAPE: \
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- __libc_alpha_cache_shape[2] = av->a_un.a_val; \
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- break; \
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- case AT_L3_CACHESHAPE: \
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- __libc_alpha_cache_shape[3] = av->a_un.a_val; \
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- break;
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+#define DL_PLATFORM_AUXV \
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+ __libc_alpha_cache_shape[0] = auxv_values[AT_L1I_CACHESHAPE]; \
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+ __libc_alpha_cache_shape[1] = auxv_values[AT_L1D_CACHESHAPE]; \
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+ __libc_alpha_cache_shape[2] = auxv_values[AT_L2_CACHESHAPE]; \
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+ __libc_alpha_cache_shape[3] = auxv_values[AT_L3_CACHESHAPE];
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diff --git a/sysdeps/unix/sysv/linux/dl-parse_auxv.h b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
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new file mode 100644
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index 0000000000000000..bf9374371eb217fc
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--- /dev/null
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+++ b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
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@@ -0,0 +1,61 @@
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+/* Parse the Linux auxiliary vector.
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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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+
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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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+
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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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+
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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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+
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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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+
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+typedef ElfW(Addr) dl_parse_auxv_t[AT_MINSIGSTKSZ + 1];
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+
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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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+
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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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+
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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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+
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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_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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+
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+ DL_PLATFORM_AUXV
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+}
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diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c
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index 3487976b06ad7f58..56db828fc6985de6 100644
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--- a/sysdeps/unix/sysv/linux/dl-sysdep.c
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+++ b/sysdeps/unix/sysv/linux/dl-sysdep.c
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@@ -18,15 +18,14 @@
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#include <_itoa.h>
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#include <assert.h>
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-#include <dl-hwcap-check.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 <entry.h>
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#include <errno.h>
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#include <fcntl.h>
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-#include <fpu_control.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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@@ -43,10 +42,9 @@
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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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-# include <dl-auxv.h>
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-
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extern char **_environ attribute_hidden;
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extern char _end[] attribute_hidden;
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@@ -64,20 +62,20 @@ void *_dl_random attribute_relro = NULL;
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# define DL_STACK_END(cookie) ((void *) (cookie))
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#endif
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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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+/* 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 = NULL;
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- ElfW(Word) phnum = 0;
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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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- ElfW(auxv_t) *av;
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-#ifdef NEED_DL_SYSINFO
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- uintptr_t new_sysinfo = 0;
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-#endif
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+};
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- __libc_stack_end = DL_STACK_END (start_argptr);
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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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@@ -89,74 +87,25 @@ _dl_sysdep_start (void **start_argptr,
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break;
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}
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- user_entry = (ElfW(Addr)) ENTRY_POINT;
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- GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */
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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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- /* 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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- GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ;
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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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- for (av = GLRO(dl_auxv); av->a_type != AT_NULL; av++)
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- switch (av->a_type)
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- {
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- case AT_PHDR:
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- phdr = (void *) av->a_un.a_val;
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- break;
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- case AT_PHNUM:
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- phnum = av->a_un.a_val;
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- break;
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- case AT_PAGESZ:
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- GLRO(dl_pagesize) = av->a_un.a_val;
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- break;
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- case AT_ENTRY:
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- user_entry = av->a_un.a_val;
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- break;
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- case AT_SECURE:
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- __libc_enable_secure = av->a_un.a_val;
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- break;
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- case AT_PLATFORM:
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- GLRO(dl_platform) = (void *) av->a_un.a_val;
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- break;
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- case AT_HWCAP:
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- GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
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- break;
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- case AT_HWCAP2:
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- GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
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- break;
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- case AT_CLKTCK:
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- GLRO(dl_clktck) = av->a_un.a_val;
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- break;
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- case AT_FPUCW:
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- GLRO(dl_fpu_control) = av->a_un.a_val;
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- break;
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-#ifdef NEED_DL_SYSINFO
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- case AT_SYSINFO:
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- new_sysinfo = av->a_un.a_val;
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- break;
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-#endif
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- case AT_SYSINFO_EHDR:
|
||
|
- GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
|
||
|
- break;
|
||
|
- 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
|
||
|
- }
|
||
|
+ElfW(Addr)
|
||
|
+_dl_sysdep_start (void **start_argptr,
|
||
|
+ void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
|
||
|
+ ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
|
||
|
+{
|
||
|
+ __libc_stack_end = DL_STACK_END (start_argptr);
|
||
|
|
||
|
- dl_hwcap_check ();
|
||
|
+ struct dl_main_arguments dl_main_args;
|
||
|
+ _dl_sysdep_parse_arguments (start_argptr, &dl_main_args);
|
||
|
|
||
|
-#ifdef NEED_DL_SYSINFO
|
||
|
- if (new_sysinfo != 0)
|
||
|
- {
|
||
|
- /* Only set the sysinfo value if we also have the vsyscall DSO. */
|
||
|
- if (GLRO(dl_sysinfo_dso) != 0)
|
||
|
- GLRO(dl_sysinfo) = new_sysinfo;
|
||
|
- }
|
||
|
-#endif
|
||
|
+ dl_hwcap_check ();
|
||
|
|
||
|
__tunables_init (_environ);
|
||
|
|
||
|
@@ -188,8 +137,9 @@ _dl_sysdep_start (void **start_argptr,
|
||
|
if (__builtin_expect (__libc_enable_secure, 0))
|
||
|
__libc_check_standard_fds ();
|
||
|
|
||
|
- (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
|
||
|
- return user_entry;
|
||
|
+ (*dl_main) (dl_main_args.phdr, dl_main_args.phnum,
|
||
|
+ &dl_main_args.user_entry, GLRO(dl_auxv));
|
||
|
+ return dl_main_args.user_entry;
|
||
|
}
|
||
|
|
||
|
void
|
||
|
diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h b/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h
|
||
|
index 36ba0f3e9e45f3e2..7f35fb531ba22098 100644
|
||
|
--- a/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h
|
||
|
+++ b/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h
|
||
|
@@ -16,15 +16,5 @@
|
||
|
License along with the GNU C Library; if not, see
|
||
|
<https://www.gnu.org/licenses/>. */
|
||
|
|
||
|
-#include <ldsodefs.h>
|
||
|
-
|
||
|
-#if IS_IN (libc) && !defined SHARED
|
||
|
-int GLRO(dl_cache_line_size);
|
||
|
-#endif
|
||
|
-
|
||
|
-/* Scan the Aux Vector for the "Data Cache Block Size" entry and assign it
|
||
|
- to dl_cache_line_size. */
|
||
|
-#define DL_PLATFORM_AUXV \
|
||
|
- case AT_DCACHEBSIZE: \
|
||
|
- GLRO(dl_cache_line_size) = av->a_un.a_val; \
|
||
|
- break;
|
||
|
+#define DL_PLATFORM_AUXV \
|
||
|
+ GLRO(dl_cache_line_size) = auxv_values[AT_DCACHEBSIZE];
|
||
|
diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-support.c b/sysdeps/unix/sysv/linux/powerpc/dl-support.c
|
||
|
new file mode 100644
|
||
|
index 0000000000000000..abe68a704946b90f
|
||
|
--- /dev/null
|
||
|
+++ b/sysdeps/unix/sysv/linux/powerpc/dl-support.c
|
||
|
@@ -0,0 +1,4 @@
|
||
|
+#include <elf/dl-support.c>
|
||
|
+
|
||
|
+/* Populated from the auxiliary vector. */
|
||
|
+int _dl_cache_line_size;
|