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Diffstat (limited to 'tools/testing/selftests/mm/pfnmap.c')
| -rw-r--r-- | tools/testing/selftests/mm/pfnmap.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/pfnmap.c b/tools/testing/selftests/mm/pfnmap.c new file mode 100644 index 000000000000..8a9d19b6020c --- /dev/null +++ b/tools/testing/selftests/mm/pfnmap.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Basic VM_PFNMAP tests relying on mmap() of '/dev/mem' + * + * Copyright 2025, Red Hat, Inc. + * + * Author(s): David Hildenbrand <david@redhat.com> + */ +#define _GNU_SOURCE +#include <stdlib.h> +#include <string.h> +#include <stdint.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <signal.h> +#include <setjmp.h> +#include <linux/mman.h> +#include <sys/mman.h> +#include <sys/wait.h> + +#include "../kselftest_harness.h" +#include "vm_util.h" + +static sigjmp_buf sigjmp_buf_env; + +static void signal_handler(int sig) +{ + siglongjmp(sigjmp_buf_env, -EFAULT); +} + +static int test_read_access(char *addr, size_t size, size_t pagesize) +{ + size_t offs; + int ret; + + if (signal(SIGSEGV, signal_handler) == SIG_ERR) + return -EINVAL; + + ret = sigsetjmp(sigjmp_buf_env, 1); + if (!ret) { + for (offs = 0; offs < size; offs += pagesize) + /* Force a read that the compiler cannot optimize out. */ + *((volatile char *)(addr + offs)); + } + if (signal(SIGSEGV, signal_handler) == SIG_ERR) + return -EINVAL; + + return ret; +} + +FIXTURE(pfnmap) +{ + size_t pagesize; + int dev_mem_fd; + char *addr1; + size_t size1; + char *addr2; + size_t size2; +}; + +FIXTURE_SETUP(pfnmap) +{ + self->pagesize = getpagesize(); + + self->dev_mem_fd = open("/dev/mem", O_RDONLY); + if (self->dev_mem_fd < 0) + SKIP(return, "Cannot open '/dev/mem'\n"); + + /* We'll require the first two pages throughout our tests ... */ + self->size1 = self->pagesize * 2; + self->addr1 = mmap(NULL, self->size1, PROT_READ, MAP_SHARED, + self->dev_mem_fd, 0); + if (self->addr1 == MAP_FAILED) + SKIP(return, "Cannot mmap '/dev/mem'\n"); + + /* ... and want to be able to read from them. */ + if (test_read_access(self->addr1, self->size1, self->pagesize)) + SKIP(return, "Cannot read-access mmap'ed '/dev/mem'\n"); + + self->size2 = 0; + self->addr2 = MAP_FAILED; +} + +FIXTURE_TEARDOWN(pfnmap) +{ + if (self->addr2 != MAP_FAILED) + munmap(self->addr2, self->size2); + if (self->addr1 != MAP_FAILED) + munmap(self->addr1, self->size1); + if (self->dev_mem_fd >= 0) + close(self->dev_mem_fd); +} + +TEST_F(pfnmap, madvise_disallowed) +{ + int advices[] = { + MADV_DONTNEED, + MADV_DONTNEED_LOCKED, + MADV_FREE, + MADV_WIPEONFORK, + MADV_COLD, + MADV_PAGEOUT, + MADV_POPULATE_READ, + MADV_POPULATE_WRITE, + }; + int i; + + /* All these advices must be rejected. */ + for (i = 0; i < ARRAY_SIZE(advices); i++) { + EXPECT_LT(madvise(self->addr1, self->pagesize, advices[i]), 0); + EXPECT_EQ(errno, EINVAL); + } +} + +TEST_F(pfnmap, munmap_split) +{ + /* + * Unmap the first page. This munmap() call is not really expected to + * fail, but we might be able to trigger other internal issues. + */ + ASSERT_EQ(munmap(self->addr1, self->pagesize), 0); + + /* + * Remap the first page while the second page is still mapped. This + * makes sure that any PAT tracking on x86 will allow for mmap()'ing + * a page again while some parts of the first mmap() are still + * around. + */ + self->size2 = self->pagesize; + self->addr2 = mmap(NULL, self->pagesize, PROT_READ, MAP_SHARED, + self->dev_mem_fd, 0); + ASSERT_NE(self->addr2, MAP_FAILED); +} + +TEST_F(pfnmap, mremap_fixed) +{ + char *ret; + + /* Reserve a destination area. */ + self->size2 = self->size1; + self->addr2 = mmap(NULL, self->size2, PROT_READ, MAP_ANON | MAP_PRIVATE, + -1, 0); + ASSERT_NE(self->addr2, MAP_FAILED); + + /* mremap() over our destination. */ + ret = mremap(self->addr1, self->size1, self->size2, + MREMAP_FIXED | MREMAP_MAYMOVE, self->addr2); + ASSERT_NE(ret, MAP_FAILED); +} + +TEST_F(pfnmap, mremap_shrink) +{ + char *ret; + + /* Shrinking is expected to work. */ + ret = mremap(self->addr1, self->size1, self->size1 - self->pagesize, 0); + ASSERT_NE(ret, MAP_FAILED); +} + +TEST_F(pfnmap, mremap_expand) +{ + /* + * Growing is not expected to work, and getting it right would + * be challenging. So this test primarily serves as an early warning + * that something that probably should never work suddenly works. + */ + self->size2 = self->size1 + self->pagesize; + self->addr2 = mremap(self->addr1, self->size1, self->size2, MREMAP_MAYMOVE); + ASSERT_EQ(self->addr2, MAP_FAILED); +} + +TEST_F(pfnmap, fork) +{ + pid_t pid; + int ret; + + /* fork() a child and test if the child can access the pages. */ + pid = fork(); + ASSERT_GE(pid, 0); + + if (!pid) { + EXPECT_EQ(test_read_access(self->addr1, self->size1, + self->pagesize), 0); + exit(0); + } + + wait(&ret); + if (WIFEXITED(ret)) + ret = WEXITSTATUS(ret); + else + ret = -EINVAL; + ASSERT_EQ(ret, 0); +} + +TEST_HARNESS_MAIN |