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9be489d778
Add check_mem_access(addr) function to check if memory at addr can be written or read returning false if memory is not accessible. This function changes signal handler for SIGSEGV and SIGBUS signals when it is called first, and it is not thread-safe. Co-authored-by: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
/* Implementation of the test verification functions for memory access
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checks.
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Copyright (C) 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 <setjmp.h>
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#include <signal.h>
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#include <support/xsignal.h>
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static sigjmp_buf sigsegv_jmp_buf;
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static void
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__sigsegv_handler (int signum)
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{
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siglongjmp (sigsegv_jmp_buf, signum);
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}
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bool check_mem_access (const void *addr, bool write)
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{
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/* This is obviously not thread-safe. */
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static bool handler_set_up;
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if (!handler_set_up)
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{
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struct sigaction sa = {
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.sa_handler = __sigsegv_handler,
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.sa_flags = SA_NODEFER,
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};
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sigemptyset (&sa.sa_mask);
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xsigaction (SIGSEGV, &sa, NULL);
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/* Some system generates SIGBUS accessing the guard area when it is
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setup with madvise. */
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xsigaction (SIGBUS, &sa, NULL);
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handler_set_up = true;
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}
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int r = sigsetjmp (sigsegv_jmp_buf, 0);
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if (r == 0)
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{
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if (write)
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*(volatile char *)addr = 'x';
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else
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*(volatile char *)addr;
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return true;
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}
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if (r == SIGSEGV || r == SIGBUS)
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return false;
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return true;
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}
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