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Fix profiling after a binutils NOTE change
Resolves: rhbz#2322754 Ref: llvm/llvm-project#114605 Ref: llvm/llvm-project#114907
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‎0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch‎

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From ccc2b792e57d632bc887b226a4e7f0a8189eab8b Mon Sep 17 00:00:00 2001
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From: Josh Stone <[email protected]>
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Date: Mon, 4 Nov 2024 16:37:49 -0800
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Subject: [PATCH] [profile] Use base+vaddr for `__llvm_write_binary_ids` note
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pointers
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This function is always examining its own ELF headers in memory, but it
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was trying to use conditions between examining files or memory, and it
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wasn't accounting for LOAD offsets at runtime. This is especially bad if
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a loaded segment has additional padding that's not in the file offsets.
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Now we do a first scan of the program headers to figure out the runtime
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base address based on `PT_PHDR` and/or `PT_DYNAMIC` (else assume zero),
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similar to libc's `do_start`. Then each `PT_NOTE` pointer is simply the
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base plus the segments's `pt_vaddr`, which includes LOAD offsets.
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Fixes #114605
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---
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.../lib/profile/InstrProfilingPlatformLinux.c | 40 ++++++++-----------
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1 file changed, 16 insertions(+), 24 deletions(-)
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diff --git a/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c b/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
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index e2c06d51e0c6..c365129a0768 100644
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--- a/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
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+++ b/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
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@@ -194,41 +194,33 @@ static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note,
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*/
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COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
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extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden")));
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+ extern ElfW(Dyn) _DYNAMIC[] __attribute__((weak, visibility("hidden")));
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+
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const ElfW(Ehdr) *ElfHeader = &__ehdr_start;
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const ElfW(Phdr) *ProgramHeader =
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(const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff);
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+ /* Compute the added base address in case of position-independent code. */
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+ uintptr_t Base = 0;
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+ for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
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+ if (ProgramHeader[I].p_type == PT_PHDR)
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+ Base = (uintptr_t)ProgramHeader - ProgramHeader[I].p_vaddr;
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+ if (ProgramHeader[I].p_type == PT_DYNAMIC && _DYNAMIC)
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+ Base = (uintptr_t)_DYNAMIC - ProgramHeader[I].p_vaddr;
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+ }
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+
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int TotalBinaryIdsSize = 0;
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- uint32_t I;
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/* Iterate through entries in the program header. */
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- for (I = 0; I < ElfHeader->e_phnum; I++) {
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+ for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
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/* Look for the notes segment in program header entries. */
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if (ProgramHeader[I].p_type != PT_NOTE)
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continue;
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/* There can be multiple notes segment, and examine each of them. */
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- const ElfW(Nhdr) * Note;
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- const ElfW(Nhdr) * NotesEnd;
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- /*
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- * When examining notes in file, use p_offset, which is the offset within
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- * the elf file, to find the start of notes.
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- */
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- if (ProgramHeader[I].p_memsz == 0 ||
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- ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) {
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- Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader +
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- ProgramHeader[I].p_offset);
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- NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) +
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- ProgramHeader[I].p_filesz);
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- } else {
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- /*
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- * When examining notes in memory, use p_vaddr, which is the address of
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- * section after loaded to memory, to find the start of notes.
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- */
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- Note =
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- (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr);
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- NotesEnd =
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- (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
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- }
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+ const ElfW(Nhdr) *Note =
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+ (const ElfW(Nhdr) *)(Base + ProgramHeader[I].p_vaddr);
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+ const ElfW(Nhdr) *NotesEnd =
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+ (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
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int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd);
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if (TotalBinaryIdsSize == -1)
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--
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2.47.0
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‎llvm.spec‎

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#region main package
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Name: %{pkg_name_llvm}
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Version: %{maj_ver}.%{min_ver}.%{patch_ver}%{?rc_ver:~rc%{rc_ver}}%{?llvm_snapshot_version_suffix:~%{llvm_snapshot_version_suffix}}
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Release: 2%{?dist}
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Release: 3%{?dist}
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Summary: The Low Level Virtual Machine
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License: Apache-2.0 WITH LLVM-exception OR NCSA
@@ -277,6 +277,12 @@ Patch501: 0001-Fix-page-size-constant-on-aarch64-and-ppc64le.patch
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# Fixes RHEL-49517.
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Patch1801: 18-99273.patch
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# Fix profiling after a binutils NOTE change.
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# https://github.com/llvm/llvm-project/pull/114907
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Patch1802: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
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Patch1903: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
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Patch2001: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
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%if 0%{?rhel} == 8
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%global python3_pkgversion 3.12
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%global __python3 /usr/bin/python3.12
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#region changelog
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%changelog
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* Mon Nov 18 2024 Josh Stone <[email protected]> - 19.1.3-3
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- Fix profiling after a binutils NOTE change (rhbz#2322754)
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* Mon Nov 18 2024 Timm Bäder <[email protected]> - 19.1.3-2
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- Install i386 config files on x86_64
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