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4c43173eba
Decorate BSS mappings with [anon: glibc: .bss <file>], for example [anon: glibc: .bss /lib/libc.so.6]. The string ".bss" is already used by bionic so use the same, but add the filename as well. If the name would be longer than what the kernel allows, drop the directory part of the path. Refactor glibc.mem.decorate_maps check to a separate function and use it to avoid assembling a name, which would not be used later. Signed-off-by: Petr Malat <oss@malat.biz> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
/* Utilities functions to name memory mappings.
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Copyright (C) 2023-2025 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 <ldsodefs.h>
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#include <setvmaname.h>
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#include <sys/prctl.h>
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#include <sysdep.h>
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#include <elf/dl-tunables.h>
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static enum {
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decorate_unknown = -1,
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decorate_off,
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decorate_on
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} decorate_maps = decorate_unknown;
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bool
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__is_decorate_maps_enabled (void)
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{
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switch (atomic_load_relaxed (&decorate_maps))
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{
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case decorate_unknown:
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if (TUNABLE_GET (glibc, mem, decorate_maps, int32_t, NULL) != 0)
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{
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atomic_store_relaxed (&decorate_maps, decorate_on);
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return true;
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}
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atomic_store_relaxed (&decorate_maps, decorate_off);
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return false;
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case decorate_off:
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return false;
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case decorate_on:
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return true;
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}
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__builtin_unreachable ();
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}
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/* If PR_SET_VMA_ANON_NAME is not supported by the kernel, prctl returns
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EINVAL. However, it also returns the same error for invalid argument.
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Since it is an internal-only API, it assumes well formatted input:
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aligned START, with (START, START+LEN) being a valid memory range,
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and NAME with a limit of 80 characters without invalid one ("\\`$[]"). */
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void
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__set_vma_name (void *start, size_t len, const char *name)
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{
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if (__is_decorate_maps_enabled ())
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{
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int r = INTERNAL_SYSCALL_CALL (prctl, PR_SET_VMA, PR_SET_VMA_ANON_NAME,
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start, len, name);
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/* Disable further attempts if not supported by the kernel. */
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if (r == -EINVAL)
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atomic_store_relaxed (&decorate_maps, decorate_off);
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}
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}
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