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-rw-r--r--string/tst-xbzero-opt.c298
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diff --git a/string/tst-xbzero-opt.c b/string/tst-xbzero-opt.c
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--- a/string/tst-xbzero-opt.c
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@@ -1,298 +0,0 @@
-/* Test that explicit_bzero block clears are not optimized out.
- Copyright (C) 2016-2017 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-/* This test is conceptually based on a test designed by Matthew
- Dempsky for the OpenBSD regression suite:
- <openbsd>/src/regress/lib/libc/explicit_bzero/explicit_bzero.c.
- The basic idea is, we have a function that contains a
- block-clearing operation (not necessarily explicit_bzero), after
- which the block is dead, in the compiler-jargon sense. Execute
- that function while running on a user-allocated alternative
- stack. Then we have another pointer to the memory region affected
- by the block clear -- namely, the original allocation for the
- alternative stack -- and can find out whether it actually happened.
-
- The OpenBSD test uses sigaltstack and SIGUSR1 to get onto an
- alternative stack. This causes a number of awkward problems; some
- operating systems (e.g. Solaris and OSX) wipe the signal stack upon
- returning to the normal stack, there's no way to be sure that other
- processes running on the same system will not interfere, and the
- signal stack is very small so it's not safe to call printf there.
- This implementation instead uses the <ucontext.h> coroutine
- interface. The coroutine stack is still too small to safely use
- printf, but we know the OS won't erase it, so we can do all the
- checks and printing from the normal stack. */
-
-#define _GNU_SOURCE 1
-
-#include <errno.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <ucontext.h>
-#include <unistd.h>
-
-/* A byte pattern that is unlikely to occur by chance: the first 16
- prime numbers (OEIS A000040). */
-static const unsigned char test_pattern[16] =
-{
- 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53
-};
-
-/* Immediately after each subtest returns, we call swapcontext to get
- back onto the main stack. That call might itself overwrite the
- test pattern, so we fill a modest-sized buffer with copies of it
- and check whether any of them survived. */
-
-#define PATTERN_SIZE (sizeof test_pattern)
-#define PATTERN_REPS 32
-#define TEST_BUFFER_SIZE (PATTERN_SIZE * PATTERN_REPS)
-
-/* There are three subtests, two of which are sanity checks.
- Each test follows this sequence:
-
- main coroutine
- ---- --------
- advance cur_subtest
- swap
- call setup function
- prepare test buffer
- swap
- verify that buffer
- was filled in
- swap
- possibly clear buffer
- return
- swap
- check buffer again,
- according to test
- expectation
-
- In the "no_clear" case, we don't do anything to the test buffer
- between preparing it and letting it go out of scope, and we expect
- to find it. This confirms that the test buffer does get filled in
- and we can find it from the stack buffer. In the "ordinary_clear"
- case, we clear it using memset. Depending on the target, the
- compiler may not be able to apply dead store elimination to the
- memset call, so the test does not fail if the memset is not
- eliminated. Finally, the "explicit_clear" case uses explicit_bzero
- and expects _not_ to find the test buffer, which is the real
- test. */
-
-static ucontext_t uc_main, uc_co;
-
-/* Always check the test buffer immediately after filling it; this
- makes externally visible side effects depend on the buffer existing
- and having been filled in. */
-static inline __attribute__ ((always_inline)) void
-prepare_test_buffer (unsigned char *buf)
-{
- for (unsigned int i = 0; i < PATTERN_REPS; i++)
- memcpy (buf + i*PATTERN_SIZE, test_pattern, PATTERN_SIZE);
-
- if (swapcontext (&uc_co, &uc_main))
- abort ();
-}
-
-static void
-setup_no_clear (void)
-{
- unsigned char buf[TEST_BUFFER_SIZE];
- prepare_test_buffer (buf);
-}
-
-static void
-setup_ordinary_clear (void)
-{
- unsigned char buf[TEST_BUFFER_SIZE];
- prepare_test_buffer (buf);
- memset (buf, 0, TEST_BUFFER_SIZE);
-}
-
-static void
-setup_explicit_clear (void)
-{
- unsigned char buf[TEST_BUFFER_SIZE];
- prepare_test_buffer (buf);
- explicit_bzero (buf, TEST_BUFFER_SIZE);
-}
-
-enum test_expectation
- {
- EXPECT_NONE, EXPECT_SOME, EXPECT_ALL, NO_EXPECTATIONS
- };
-struct subtest
-{
- void (*setup_subtest) (void);
- const char *label;
- enum test_expectation expected;
-};
-static const struct subtest *cur_subtest;
-
-static const struct subtest subtests[] =
-{
- { setup_no_clear, "no clear", EXPECT_SOME },
- /* The memset may happen or not, depending on compiler
- optimizations. */
- { setup_ordinary_clear, "ordinary clear", NO_EXPECTATIONS },
- { setup_explicit_clear, "explicit clear", EXPECT_NONE },
- { 0, 0, -1 }
-};
-
-static void
-test_coroutine (void)
-{
- while (cur_subtest->setup_subtest)
- {
- cur_subtest->setup_subtest ();
- if (swapcontext (&uc_co, &uc_main))
- abort ();
- }
-}
-
-/* All the code above this point runs on the coroutine stack.
- All the code below this point runs on the main stack. */
-
-static int test_status;
-static unsigned char *co_stack_buffer;
-static size_t co_stack_size;
-
-static unsigned int
-count_test_patterns (unsigned char *buf, size_t bufsiz)
-{
- unsigned char *first = memmem (buf, bufsiz, test_pattern, PATTERN_SIZE);
- if (!first)
- return 0;
- unsigned int cnt = 0;
- for (unsigned int i = 0; i < PATTERN_REPS; i++)
- {
- unsigned char *p = first + i*PATTERN_SIZE;
- if (p + PATTERN_SIZE - buf > bufsiz)
- break;
- if (memcmp (p, test_pattern, PATTERN_SIZE) == 0)
- cnt++;
- }
- return cnt;
-}
-
-static void
-check_test_buffer (enum test_expectation expected,
- const char *label, const char *stage)
-{
- unsigned int cnt = count_test_patterns (co_stack_buffer, co_stack_size);
- switch (expected)
- {
- case EXPECT_NONE:
- if (cnt == 0)
- printf ("PASS: %s/%s: expected 0 got %d\n", label, stage, cnt);
- else
- {
- printf ("FAIL: %s/%s: expected 0 got %d\n", label, stage, cnt);
- test_status = 1;
- }
- break;
-
- case EXPECT_SOME:
- if (cnt > 0)
- printf ("PASS: %s/%s: expected some got %d\n", label, stage, cnt);
- else
- {
- printf ("FAIL: %s/%s: expected some got 0\n", label, stage);
- test_status = 1;
- }
- break;
-
- case EXPECT_ALL:
- if (cnt == PATTERN_REPS)
- printf ("PASS: %s/%s: expected %d got %d\n", label, stage,
- PATTERN_REPS, cnt);
- else
- {
- printf ("FAIL: %s/%s: expected %d got %d\n", label, stage,
- PATTERN_REPS, cnt);
- test_status = 1;
- }
- break;
-
- case NO_EXPECTATIONS:
- printf ("INFO: %s/%s: found %d patterns%s\n", label, stage, cnt,
- cnt == 0 ? " (memset not eliminated)" : "");
- break;
-
- default:
- printf ("ERROR: %s/%s: invalid value for 'expected' = %d\n",
- label, stage, (int)expected);
- test_status = 1;
- }
-}
-
-static void
-test_loop (void)
-{
- cur_subtest = subtests;
- while (cur_subtest->setup_subtest)
- {
- if (swapcontext (&uc_main, &uc_co))
- abort ();
- check_test_buffer (EXPECT_ALL, cur_subtest->label, "prepare");
- if (swapcontext (&uc_main, &uc_co))
- abort ();
- check_test_buffer (cur_subtest->expected, cur_subtest->label, "test");
- cur_subtest++;
- }
- /* Terminate the coroutine. */
- if (swapcontext (&uc_main, &uc_co))
- abort ();
-}
-
-int
-do_test (void)
-{
- size_t page_alignment = sysconf (_SC_PAGESIZE);
- if (page_alignment < sizeof (void *))
- page_alignment = sizeof (void *);
-
- co_stack_size = SIGSTKSZ + TEST_BUFFER_SIZE;
- if (co_stack_size < page_alignment * 4)
- co_stack_size = page_alignment * 4;
-
- void *p;
- int err = posix_memalign (&p, page_alignment, co_stack_size);
- if (err || !p)
- {
- printf ("ERROR: allocating alt stack: %s\n", strerror (err));
- return 2;
- }
- co_stack_buffer = p;
-
- if (getcontext (&uc_co))
- {
- printf ("ERROR: allocating coroutine context: %s\n", strerror (err));
- return 2;
- }
- uc_co.uc_stack.ss_sp = co_stack_buffer;
- uc_co.uc_stack.ss_size = co_stack_size;
- uc_co.uc_link = &uc_main;
- makecontext (&uc_co, test_coroutine, 0);
-
- test_loop ();
- return test_status;
-}
-
-#include <support/test-driver.c>
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