On Sun 14-10-18 00:39:29, Michael Ellerman wrote: > Add a test for MAP_FIXED_NOREPLACE, based on some code originally by > Jann Horn. This would have caught the overlap bug reported by Daniel Micay. > > I originally suggested to Michal that we create MAP_FIXED_NOREPLACE, but > instead of writing a selftest I spent my time bike-shedding whether it > should be called MAP_FIXED_SAFE/NOCLOBBER/WEAK/NEW .. mea culpa.
You wer one of those to provide a useful feedback actually. So no reason to feel sorry. I should have been forced to write a test case instead. No idea why I haven't considered that myself actually. So I steal your culpa here. > Signed-off-by: Michael Ellerman <[email protected]> Thanks for doing this! Acked-by: Michal Hocko <[email protected]> > --- > tools/testing/selftests/vm/.gitignore | 1 + > tools/testing/selftests/vm/Makefile | 1 + > .../selftests/vm/map_fixed_noreplace.c | 206 ++++++++++++++++++ > 3 files changed, 208 insertions(+) > create mode 100644 tools/testing/selftests/vm/map_fixed_noreplace.c > > diff --git a/tools/testing/selftests/vm/.gitignore > b/tools/testing/selftests/vm/.gitignore > index af5ff83f6d7f..31b3c98b6d34 100644 > --- a/tools/testing/selftests/vm/.gitignore > +++ b/tools/testing/selftests/vm/.gitignore > @@ -13,3 +13,4 @@ mlock-random-test > virtual_address_range > gup_benchmark > va_128TBswitch > +map_fixed_noreplace > diff --git a/tools/testing/selftests/vm/Makefile > b/tools/testing/selftests/vm/Makefile > index e94b7b14bcb2..6e67e726e5a5 100644 > --- a/tools/testing/selftests/vm/Makefile > +++ b/tools/testing/selftests/vm/Makefile > @@ -12,6 +12,7 @@ TEST_GEN_FILES += gup_benchmark > TEST_GEN_FILES += hugepage-mmap > TEST_GEN_FILES += hugepage-shm > TEST_GEN_FILES += map_hugetlb > +TEST_GEN_FILES += map_fixed_noreplace > TEST_GEN_FILES += map_populate > TEST_GEN_FILES += mlock-random-test > TEST_GEN_FILES += mlock2-tests > diff --git a/tools/testing/selftests/vm/map_fixed_noreplace.c > b/tools/testing/selftests/vm/map_fixed_noreplace.c > new file mode 100644 > index 000000000000..d91bde511268 > --- /dev/null > +++ b/tools/testing/selftests/vm/map_fixed_noreplace.c > @@ -0,0 +1,206 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Test that MAP_FIXED_NOREPLACE works. > + * > + * Copyright 2018, Jann Horn <[email protected]> > + * Copyright 2018, Michael Ellerman, IBM Corporation. > + */ > + > +#include <sys/mman.h> > +#include <errno.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <unistd.h> > + > +#ifndef MAP_FIXED_NOREPLACE > +#define MAP_FIXED_NOREPLACE 0x100000 > +#endif > + > +#define BASE_ADDRESS (256ul * 1024 * 1024) > + > + > +static void dump_maps(void) > +{ > + char cmd[32]; > + > + snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid()); > + system(cmd); > +} > + > +int main(void) > +{ > + unsigned long flags, addr, size, page_size; > + char *p; > + > + page_size = sysconf(_SC_PAGE_SIZE); > + > + flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE; > + > + // Check we can map all the areas we need below > + errno = 0; > + addr = BASE_ADDRESS; > + size = 5 * page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p == MAP_FAILED) { > + dump_maps(); > + printf("Error: couldn't map the space we need for the test\n"); > + return 1; > + } > + > + errno = 0; > + if (munmap((void *)addr, 5 * page_size) != 0) { > + dump_maps(); > + printf("Error: munmap failed!?\n"); > + return 1; > + } > + printf("unmap() successful\n"); > + > + errno = 0; > + addr = BASE_ADDRESS + page_size; > + size = 3 * page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p == MAP_FAILED) { > + dump_maps(); > + printf("Error: first mmap() failed unexpectedly\n"); > + return 1; > + } > + > + /* > + * Exact same mapping again: > + * base | free | new > + * +1 | mapped | new > + * +2 | mapped | new > + * +3 | mapped | new > + * +4 | free | new > + */ > + errno = 0; > + addr = BASE_ADDRESS; > + size = 5 * page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p != MAP_FAILED) { > + dump_maps(); > + printf("Error:1: mmap() succeeded when it shouldn't have\n"); > + return 1; > + } > + > + /* > + * Second mapping contained within first: > + * > + * base | free | > + * +1 | mapped | > + * +2 | mapped | new > + * +3 | mapped | > + * +4 | free | > + */ > + errno = 0; > + addr = BASE_ADDRESS + (2 * page_size); > + size = page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p != MAP_FAILED) { > + dump_maps(); > + printf("Error:2: mmap() succeeded when it shouldn't have\n"); > + return 1; > + } > + > + /* > + * Overlap end of existing mapping: > + * base | free | > + * +1 | mapped | > + * +2 | mapped | > + * +3 | mapped | new > + * +4 | free | new > + */ > + errno = 0; > + addr = BASE_ADDRESS + (3 * page_size); > + size = 2 * page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p != MAP_FAILED) { > + dump_maps(); > + printf("Error:3: mmap() succeeded when it shouldn't have\n"); > + return 1; > + } > + > + /* > + * Overlap start of existing mapping: > + * base | free | new > + * +1 | mapped | new > + * +2 | mapped | > + * +3 | mapped | > + * +4 | free | > + */ > + errno = 0; > + addr = BASE_ADDRESS; > + size = 2 * page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p != MAP_FAILED) { > + dump_maps(); > + printf("Error:4: mmap() succeeded when it shouldn't have\n"); > + return 1; > + } > + > + /* > + * Adjacent to start of existing mapping: > + * base | free | new > + * +1 | mapped | > + * +2 | mapped | > + * +3 | mapped | > + * +4 | free | > + */ > + errno = 0; > + addr = BASE_ADDRESS; > + size = page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p == MAP_FAILED) { > + dump_maps(); > + printf("Error:5: mmap() failed when it shouldn't have\n"); > + return 1; > + } > + > + /* > + * Adjacent to end of existing mapping: > + * base | free | > + * +1 | mapped | > + * +2 | mapped | > + * +3 | mapped | > + * +4 | free | new > + */ > + errno = 0; > + addr = BASE_ADDRESS + (4 * page_size); > + size = page_size; > + p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0); > + printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p); > + > + if (p == MAP_FAILED) { > + dump_maps(); > + printf("Error:6: mmap() failed when it shouldn't have\n"); > + return 1; > + } > + > + addr = BASE_ADDRESS; > + size = 5 * page_size; > + if (munmap((void *)addr, size) != 0) { > + dump_maps(); > + printf("Error: munmap failed!?\n"); > + return 1; > + } > + printf("unmap() successful\n"); > + > + printf("OK\n"); > + return 0; > +} > -- > 2.17.1 > -- Michal Hocko SUSE Labs
