Commit 206e22f0 authored by Chris Kennelly's avatar Chris Kennelly Committed by Linus Torvalds
Browse files

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.

Signed-off-by: default avatarChris Kennelly <ckennelly@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Link: https://lkml.kernel.org/r/20200820170541.1132271-3-ckennelly@google.com
Link: https://lkml.kernel.org/r/20200821233848.3904680-3-ckennelly@google.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ce81bb25

tools/testing/selftests/exec/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ execveat.moved 
execveat.path.ephemeral

execveat.ephemeral

execveat.denatured

/load_address_*

/recursion-depth

xxxxxxxx*

pipe

tools/testing/selftests/exec/Makefile

+7 −2
Original line number Diff line number Diff line
@@ -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)/execveat 
$(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 $@

tools/testing/selftests/exec/load_address.c

0 → 100644
+68 −0
Original line number Diff line number Diff line 
// 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;

}