tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
selftests/powerpc: Add a test of SEGV error behaviour
Add a test case of the error code reported when we take a SEGV on a
mapped but inaccessible area. We broke this recently.
Based on a test case from John Sperbeck <jsperbeck@google.com>.
Acked-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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tools/testing/selftests/powerpc/mm/.gitignore
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tools/testing/selftests/powerpc/mm/.gitignore
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tools/testing/selftests/powerpc/mm/Makefile
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tools/testing/selftests/powerpc/mm/Makefile
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tools/testing/selftests/powerpc/mm/segv_errors.c
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tools/testing/selftests/powerpc/mm/segv_errors.c
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright 2017 John Sperbeck
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*
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* Test that an access to a mapped but inaccessible area causes a SEGV and
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* reports si_code == SEGV_ACCERR.
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*/
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <signal.h>
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#include <sys/mman.h>
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#include <assert.h>
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#include <ucontext.h>
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#include "utils.h"
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static bool faulted;
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static int si_code;
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static void segv_handler(int n, siginfo_t *info, void *ctxt_v)
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{
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ucontext_t *ctxt = (ucontext_t *)ctxt_v;
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struct pt_regs *regs = ctxt->uc_mcontext.regs;
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faulted = true;
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si_code = info->si_code;
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regs->nip += 4;
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}
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int test_segv_errors(void)
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{
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struct sigaction act = {
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.sa_sigaction = segv_handler,
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.sa_flags = SA_SIGINFO,
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};
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char c, *p = NULL;
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p = mmap(NULL, getpagesize(), 0, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
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FAIL_IF(p == MAP_FAILED);
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FAIL_IF(sigaction(SIGSEGV, &act, NULL) != 0);
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faulted = false;
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si_code = 0;
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/*
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* We just need a compiler barrier, but mb() works and has the nice
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* property of being easy to spot in the disassembly.
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*/
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mb();
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c = *p;
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mb();
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FAIL_IF(!faulted);
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FAIL_IF(si_code != SEGV_ACCERR);
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faulted = false;
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si_code = 0;
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mb();
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*p = c;
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mb();
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FAIL_IF(!faulted);
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FAIL_IF(si_code != SEGV_ACCERR);
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return 0;
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}
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int main(void)
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{
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return test_harness(test_segv_errors, "segv_errors");
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}