From: Chris Kennelly <ckennelly@xxxxxxxxxx> Subject: tools/testing/selftests: add self-test for verifying load alignment This produces a PIE binary with a variety of p_align requirements, suitable for verifying that the load address meets that alignment requirement. Link: https://lkml.kernel.org/r/20200820170541.1132271-3-ckennelly@xxxxxxxxxx Link: https://lkml.kernel.org/r/20200821233848.3904680-3-ckennelly@xxxxxxxxxx Signed-off-by: Chris Kennelly <ckennelly@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Fangrui Song <maskray@xxxxxxxxxx> Cc: Hugh Dickens <hughd@xxxxxxxxxx> Cc: Ian Rogers <irogers@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Cc: Sandeep Patil <sspatil@xxxxxxxxxx> Cc: Song Liu <songliubraving@xxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/exec/.gitignore | 1 tools/testing/selftests/exec/Makefile | 9 +- tools/testing/selftests/exec/load_address.c | 68 ++++++++++++++++++ 3 files changed, 76 insertions(+), 2 deletions(-) --- a/tools/testing/selftests/exec/.gitignore~add-self-test-for-verifying-load-alignment +++ a/tools/testing/selftests/exec/.gitignore @@ -7,6 +7,7 @@ execveat.moved execveat.path.ephemeral execveat.ephemeral execveat.denatured +/load_address_* /recursion-depth xxxxxxxx* pipe --- /dev/null +++ a/tools/testing/selftests/exec/load_address.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0-only +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif +#include <link.h> +#include <stdio.h> +#include <stdlib.h> + +struct Statistics { + unsigned long long load_address; + unsigned long long alignment; +}; + +int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data) +{ + struct Statistics *stats = (struct Statistics *) data; + int i; + + if (info->dlpi_name != NULL && info->dlpi_name[0] != '\0') { + // Ignore headers from other than the executable. + return 2; + } + + stats->load_address = (unsigned long long) info->dlpi_addr; + stats->alignment = 0; + + for (i = 0; i < info->dlpi_phnum; i++) { + if (info->dlpi_phdr[i].p_type != PT_LOAD) + continue; + + if (info->dlpi_phdr[i].p_align > stats->alignment) + stats->alignment = info->dlpi_phdr[i].p_align; + } + + return 1; // Terminate dl_iterate_phdr. +} + +int main(int argc, char **argv) +{ + struct Statistics extracted; + unsigned long long misalign; + int ret; + + ret = dl_iterate_phdr(ExtractStatistics, &extracted); + if (ret != 1) { + fprintf(stderr, "FAILED\n"); + return 1; + } + + if (extracted.alignment == 0) { + fprintf(stderr, "No alignment found\n"); + return 1; + } else if (extracted.alignment & (extracted.alignment - 1)) { + fprintf(stderr, "Alignment is not a power of 2\n"); + return 1; + } + + misalign = extracted.load_address & (extracted.alignment - 1); + if (misalign) { + printf("alignment = %llu, load_address = %llu\n", + extracted.alignment, extracted.load_address); + fprintf(stderr, "FAILED\n"); + return 1; + } + + fprintf(stderr, "PASS\n"); + return 0; +} --- a/tools/testing/selftests/exec/Makefile~add-self-test-for-verifying-load-alignment +++ a/tools/testing/selftests/exec/Makefile @@ -4,7 +4,7 @@ CFLAGS += -Wno-nonnull CFLAGS += -D_GNU_SOURCE TEST_PROGS := binfmt_script non-regular -TEST_GEN_PROGS := execveat +TEST_GEN_PROGS := execveat load_address_4096 load_address_2097152 load_address_16777216 TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir pipe # Makefile is a run-time dependency, since it's accessed by the execveat test TEST_FILES := Makefile @@ -27,4 +27,9 @@ $(OUTPUT)/execveat.symlink: $(OUTPUT)/ex $(OUTPUT)/execveat.denatured: $(OUTPUT)/execveat cp $< $@ chmod -x $@ - +$(OUTPUT)/load_address_4096: load_address.c + $(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x1000 -pie $< -o $@ +$(OUTPUT)/load_address_2097152: load_address.c + $(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x200000 -pie $< -o $@ +$(OUTPUT)/load_address_16777216: load_address.c + $(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x1000000 -pie $< -o $@ _
