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: Chris Kennelly <ckennelly@google.com>
Signed-off-by: Andrew 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: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/exec/.gitignore b/tools/testing/selftests/exec/.gitignore
index 344a99c..9e2f003 100644 (file)
--- a/tools/testing/selftests/exec/.gitignore
+++ b/tools/testing/selftests/exec/.gitignore
@@ -7,6 +7,7 @@ execveat.moved
 execveat.path.ephemeral
 execveat.ephemeral
 execveat.denatured
+/load_address_*
 /recursion-depth
 xxxxxxxx*
 pipe

diff --git a/tools/testing/selftests/exec/Makefile b/tools/testing/selftests/exec/Makefile
index 0a13b11..cf69b2f 100644 (file)
--- a/tools/testing/selftests/exec/Makefile
+++ b/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)/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 $@

diff --git a/tools/testing/selftests/exec/load_address.c b/tools/testing/selftests/exec/load_address.c
new file mode 100644 (file)
index 0000000..d487c2f
--- /dev/null
+++ b/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;
+}