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authorGravatar Benjamin Barenblat <bbaren@google.com>2023-08-02 12:58:13 -0400
committerGravatar Benjamin Barenblat <bbaren@google.com>2023-08-02 12:58:13 -0400
commit8b8ba810c157a6b3e3a517014198648999d7808e (patch)
treeffec15b626aa008d9608cc23e71039b43b3278b5 /debian
parent17046ae7503e82dd8484584619413eab688fa717 (diff)
Fix unit tests on ppc64
Backport a patch from upstream to fix symbolization on ppc64, and enable unit tests on that platform.
Diffstat (limited to 'debian')
-rw-r--r--debian/changelog2
-rw-r--r--debian/patches/series1
-rw-r--r--debian/patches/symbolize-ppc64.diff118
-rwxr-xr-xdebian/rules4
4 files changed, 122 insertions, 3 deletions
diff --git a/debian/changelog b/debian/changelog
index 6abc1938..9a6cdc08 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,8 @@ abseil (20230125.3-2) UNRELEASED; urgency=medium
* Reenable unit tests, which were accidentally disabled in the previous
version.
* Backport an upstream patch to allow building tests on mipsel.
+ * Backport a patch from upstream to correct symbolization on ppc64, and
+ enable unit tests on that platform.
-- Benjamin Barenblat <bbaren@debian.org> Tue, 27 Jun 2023 17:00:12 -0400
diff --git a/debian/patches/series b/debian/patches/series
index 66bf33ce..000d6558 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -5,3 +5,4 @@ empty-flags-library.diff
cordz-info-statistics-test.diff
pkg-config-directives.diff
split-hash-tests.diff
+symbolize-ppc64.diff
diff --git a/debian/patches/symbolize-ppc64.diff b/debian/patches/symbolize-ppc64.diff
new file mode 100644
index 00000000..a11c27d4
--- /dev/null
+++ b/debian/patches/symbolize-ppc64.diff
@@ -0,0 +1,118 @@
+From: Benjamin Barenblat <bbaren@google.com>
+Subject: Fix symbolization on PowerPC ELF v1
+Origin: backport, https://github.com/abseil/abseil-cpp/commit/372bfc86105728732fc115af46223d7a4e49f8d9
+
+The big-endian PowerPC ELF ABI (ppc64 in Debian) relies on function descriptors
+mapped in a non-executable segment. Make sure that segment is scanned during
+symbolization. Also correct bounds computation for that segment.
+
+--- a/absl/debugging/symbolize_elf.inc
++++ b/absl/debugging/symbolize_elf.inc
+@@ -648,8 +648,10 @@
+ }
+
+ // Return true if an address is inside a section.
+-static bool InSection(const void *address, const ElfW(Shdr) * section) {
+- const char *start = reinterpret_cast<const char *>(section->sh_addr);
++static bool InSection(const void *address, ptrdiff_t relocation,
++ const ElfW(Shdr) * section) {
++ const char *start = reinterpret_cast<const char *>(
++ section->sh_addr + static_cast<ElfW(Addr)>(relocation));
+ size_t size = static_cast<size_t>(section->sh_size);
+ return start <= address && address < (start + size);
+ }
+@@ -689,8 +691,8 @@
+ // starting address. However, we do not always want to use the real
+ // starting address because we sometimes want to symbolize a function
+ // pointer into the .opd section, e.g. FindSymbol(&foo,...).
+- const bool pc_in_opd =
+- kPlatformUsesOPDSections && opd != nullptr && InSection(pc, opd);
++ const bool pc_in_opd = kPlatformUsesOPDSections && opd != nullptr &&
++ InSection(pc, relocation, opd);
+ const bool deref_function_descriptor_pointer =
+ kPlatformUsesOPDSections && opd != nullptr && !pc_in_opd;
+
+@@ -730,7 +732,7 @@
+ #endif
+
+ if (deref_function_descriptor_pointer &&
+- InSection(original_start_address, opd)) {
++ InSection(original_start_address, /*relocation=*/0, opd)) {
+ // The opd section is mapped into memory. Just dereference
+ // start_address to get the first double word, which points to the
+ // function entry.
+@@ -1326,7 +1328,7 @@
+ const int phnum = obj->elf_header.e_phnum;
+ const int phentsize = obj->elf_header.e_phentsize;
+ auto phoff = static_cast<off_t>(obj->elf_header.e_phoff);
+- size_t num_executable_load_segments = 0;
++ size_t num_interesting_load_segments = 0;
+ for (int j = 0; j < phnum; j++) {
+ ElfW(Phdr) phdr;
+ if (!ReadFromOffsetExact(obj->fd, &phdr, sizeof(phdr), phoff)) {
+@@ -1335,23 +1337,35 @@
+ return false;
+ }
+ phoff += phentsize;
+- constexpr int rx = PF_X | PF_R;
+- if (phdr.p_type != PT_LOAD || (phdr.p_flags & rx) != rx) {
+- // Not a LOAD segment, or not executable code.
++
++#if defined(__powerpc__) && !(_CALL_ELF > 1)
++ // On the PowerPC ELF v1 ABI, function pointers actually point to function
++ // descriptors. These descriptors are stored in an .opd section, which is
++ // mapped read-only. We thus need to look at all readable segments, not
++ // just the executable ones.
++ constexpr int interesting = PF_R;
++#else
++ constexpr int interesting = PF_X | PF_R;
++#endif
++
++ if (phdr.p_type != PT_LOAD
++ || (phdr.p_flags & interesting) != interesting) {
++ // Not a LOAD segment, not executable code, and not a function
++ // descriptor.
+ continue;
+ }
+- if (num_executable_load_segments < obj->phdr.size()) {
+- memcpy(&obj->phdr[num_executable_load_segments++], &phdr, sizeof(phdr));
++ if (num_interesting_load_segments < obj->phdr.size()) {
++ memcpy(&obj->phdr[num_interesting_load_segments++], &phdr, sizeof(phdr));
+ } else {
+ ABSL_RAW_LOG(
+- WARNING, "%s: too many executable LOAD segments: %zu >= %zu",
+- obj->filename, num_executable_load_segments, obj->phdr.size());
++ WARNING, "%s: too many interesting LOAD segments: %zu >= %zu",
++ obj->filename, num_interesting_load_segments, obj->phdr.size());
+ break;
+ }
+ }
+- if (num_executable_load_segments == 0) {
+- // This object has no "r-x" LOAD segments. That's unexpected.
+- ABSL_RAW_LOG(WARNING, "%s: no executable LOAD segments", obj->filename);
++ if (num_interesting_load_segments == 0) {
++ // This object has no interesting LOAD segments. That's unexpected.
++ ABSL_RAW_LOG(WARNING, "%s: no interesting LOAD segments", obj->filename);
+ return false;
+ }
+ }
+@@ -1379,8 +1393,8 @@
+ // X in the file will have a start address of [true relocation]+X.
+ relocation = static_cast<ptrdiff_t>(start_addr - obj->offset);
+
+- // Note: some binaries have multiple "rx" LOAD segments. We must
+- // find the right one.
++ // Note: some binaries have multiple LOAD segments that can contain
++ // function pointers. We must find the right one.
+ ElfW(Phdr) *phdr = nullptr;
+ for (size_t j = 0; j < obj->phdr.size(); j++) {
+ ElfW(Phdr) &p = obj->phdr[j];
+@@ -1390,7 +1404,7 @@
+ ABSL_RAW_CHECK(p.p_type == PT_NULL, "unexpected p_type");
+ break;
+ }
+- if (pc < reinterpret_cast<void *>(start_addr + p.p_memsz)) {
++ if (pc < reinterpret_cast<void *>(start_addr + p.p_vaddr + p.p_memsz)) {
+ phdr = &p;
+ break;
+ }
diff --git a/debian/rules b/debian/rules
index e835a80d..7f76c033 100755
--- a/debian/rules
+++ b/debian/rules
@@ -19,10 +19,8 @@ export DEB_BUILD_MAINT_OPTIONS = hardening=+bindnow reproducible=+fixfilepath
# Unit tests require more than 2 GB of RAM, so disable them on mipsel.
#
-# Unit tests are not yet passing on ppc64, so disable them there as well.
-#
# Disable unit tests unconditionally if nocheck is set.
-ifneq ($(filter $(DEB_HOST_ARCH),mipsel ppc64),)
+ifeq ($(DEB_HOST_ARCH),mipsel)
ABSL_RUN_TESTS=OFF
else ifneq ($(filter nocheck,$(DEB_BUILD_OPTIONS)),)
ABSL_RUN_TESTS=OFF