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PR #1874: Simplify detection of the powerpc64 ELFv1 ABI

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Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1874

Compilers for 32-bit powerpc may not define `_CALL_ELF`.

Squelches an undefined warning from GCC.
Fix the pre-processor check, and in turn fix the `symbolize_test` on 32-bit powerpc.

Merge cffd4a4197 into daa0bfb568

Merging this change closes #1874

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1874 from SeanMcG:ppc64_elfv2_detect_fix cffd4a4197
PiperOrigin-RevId: 748379689
Change-Id: Id0c9e28a6c45482ff9262c2e5b16d2810ada1c4b
This commit is contained in:
Sean McGovern
2025-04-16 12:15:01 -07:00
committed by Copybara-Service
parent 6e7a7bfe6b
commit 3f242f22e5
1 changed files with 19 additions and 9 deletions
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28
absl/debugging/symbolize_elf.inc
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@@ -125,12 +125,20 @@ namespace {
// Some platforms use a special .opd section to store function pointers.
const char kOpdSectionName[] = ".opd";
#if (defined(__powerpc__) && !(_CALL_ELF > 1)) || defined(__ia64)
#if defined(__powerpc64__) && defined(_CALL_ELF)
#if _CALL_ELF <= 1
#define ABSL_INTERNAL_HAVE_PPC64_ELFV1_ABI 1
#endif
#endif
#if defined(ABSL_INTERNAL_HAVE_PPC64_ELFV1_ABI) || defined(__ia64)
// Use opd section for function descriptors on these platforms, the function
// address is the first word of the descriptor.
enum { kPlatformUsesOPDSections = 1 };
#else // not PPC or IA64
enum { kPlatformUsesOPDSections = 0 };
//
// https://maskray.me/blog/2023-02-26-linker-notes-on-power-isa notes that
// opd sections are used on 64-bit PowerPC with the ELFv1 ABI.
inline constexpr bool kPlatformUsesOPDSections = true;
#else
inline constexpr bool kPlatformUsesOPDSections = false;
#endif
// This works for PowerPC & IA64 only. A function descriptor consist of two
@@ -1451,11 +1459,11 @@ static bool MaybeInitializeObjFile(ObjFile *obj) {
}
phoff += phentsize;
#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.
#ifdef ABSL_INTERNAL_HAVE_PPC64_ELFV1_ABI
// On the PowerPC 64-bit ELFv1 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;
@@ -1762,3 +1770,5 @@ extern "C" bool AbslInternalGetFileMappingHint(const void **start,
return absl::debugging_internal::GetFileMappingHint(start, end, offset,
filename);
}
#undef ABSL_INTERNAL_HAVE_PPC64_ELFV1_ABI