diff options
Diffstat (limited to 'tools/testing/selftests/mm/guard-pages.c')
| -rw-r--r-- | tools/testing/selftests/mm/guard-pages.c | 89 |
1 files changed, 79 insertions, 10 deletions
diff --git a/tools/testing/selftests/mm/guard-pages.c b/tools/testing/selftests/mm/guard-pages.c index 7cdf815d0d63..525c50d3ec23 100644 --- a/tools/testing/selftests/mm/guard-pages.c +++ b/tools/testing/selftests/mm/guard-pages.c @@ -19,6 +19,8 @@ #include <sys/uio.h> #include <unistd.h> +#include "../pidfd/pidfd.h" + /* * Ignore the checkpatch warning, as per the C99 standard, section 7.14.1.1: * @@ -50,9 +52,10 @@ static void handle_fatal(int c) siglongjmp(signal_jmp_buf, c); } -static int pidfd_open(pid_t pid, unsigned int flags) +static ssize_t sys_process_madvise(int pidfd, const struct iovec *iovec, + size_t n, int advice, unsigned int flags) { - return syscall(SYS_pidfd_open, pid, flags); + return syscall(__NR_process_madvise, pidfd, iovec, n, advice, flags); } /* @@ -364,14 +367,10 @@ TEST_F(guard_pages, multi_vma) TEST_F(guard_pages, process_madvise) { const unsigned long page_size = self->page_size; - pid_t pid = getpid(); - int pidfd = pidfd_open(pid, 0); char *ptr_region, *ptr1, *ptr2, *ptr3; ssize_t count; struct iovec vec[6]; - ASSERT_NE(pidfd, -1); - /* Reserve region to map over. */ ptr_region = mmap(NULL, 100 * page_size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0); @@ -419,7 +418,7 @@ TEST_F(guard_pages, process_madvise) ASSERT_EQ(munmap(&ptr_region[99 * page_size], page_size), 0); /* Now guard in one step. */ - count = process_madvise(pidfd, vec, 6, MADV_GUARD_INSTALL, 0); + count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_INSTALL, 0); /* OK we don't have permission to do this, skip. */ if (count == -1 && errno == EPERM) @@ -440,7 +439,7 @@ TEST_F(guard_pages, process_madvise) ASSERT_FALSE(try_read_write_buf(&ptr3[19 * page_size])); /* Now do the same with unguard... */ - count = process_madvise(pidfd, vec, 6, MADV_GUARD_REMOVE, 0); + count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_REMOVE, 0); /* ...and everything should now succeed. */ @@ -457,7 +456,6 @@ TEST_F(guard_pages, process_madvise) ASSERT_EQ(munmap(ptr1, 10 * page_size), 0); ASSERT_EQ(munmap(ptr2, 5 * page_size), 0); ASSERT_EQ(munmap(ptr3, 20 * page_size), 0); - close(pidfd); } /* Assert that unmapping ranges does not leave guard markers behind. */ @@ -990,7 +988,7 @@ TEST_F(guard_pages, fork) MAP_ANON | MAP_PRIVATE, -1, 0); ASSERT_NE(ptr, MAP_FAILED); - /* Establish guard apges in the first 5 pages. */ + /* Establish guard pages in the first 5 pages. */ ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0); pid = fork(); @@ -1030,6 +1028,77 @@ TEST_F(guard_pages, fork) } /* + * Assert expected behaviour after we fork populated ranges of anonymous memory + * and then guard and unguard the range. + */ +TEST_F(guard_pages, fork_cow) +{ + const unsigned long page_size = self->page_size; + char *ptr; + pid_t pid; + int i; + + /* Map 10 pages. */ + ptr = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE, -1, 0); + ASSERT_NE(ptr, MAP_FAILED); + + /* Populate range. */ + for (i = 0; i < 10 * page_size; i++) { + char chr = 'a' + (i % 26); + + ptr[i] = chr; + } + + pid = fork(); + ASSERT_NE(pid, -1); + if (!pid) { + /* This is the child process now. */ + + /* Ensure the range is as expected. */ + for (i = 0; i < 10 * page_size; i++) { + char expected = 'a' + (i % 26); + char actual = ptr[i]; + + ASSERT_EQ(actual, expected); + } + + /* Establish guard pages across the whole range. */ + ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0); + /* Remove it. */ + ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0); + + /* + * By removing the guard pages, the page tables will be + * cleared. Assert that we are looking at the zero page now. + */ + for (i = 0; i < 10 * page_size; i++) { + char actual = ptr[i]; + + ASSERT_EQ(actual, '\0'); + } + + exit(0); + } + + /* Parent process. */ + + /* Parent simply waits on child. */ + waitpid(pid, NULL, 0); + + /* Ensure the range is unchanged in parent anon range. */ + for (i = 0; i < 10 * page_size; i++) { + char expected = 'a' + (i % 26); + char actual = ptr[i]; + + ASSERT_EQ(actual, expected); + } + + /* Cleanup. */ + ASSERT_EQ(munmap(ptr, 10 * page_size), 0); +} + +/* * Assert that forking a process with VMAs that do have VM_WIPEONFORK set * behave as expected. */ |