Fix profiling after a binutils NOTE change

Resolves: rhbz#2322754
Ref: https://github.com/llvm/llvm-project/issues/114605
Ref: https://github.com/llvm/llvm-project/pull/114907
This commit is contained in:
Josh Stone 2024-11-18 14:39:41 -08:00
parent 5bc80c81ed
commit 680f925c31
2 changed files with 96 additions and 1 deletions

View file

@ -0,0 +1,86 @@
From ccc2b792e57d632bc887b226a4e7f0a8189eab8b Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Mon, 4 Nov 2024 16:37:49 -0800
Subject: [PATCH] [profile] Use base+vaddr for `__llvm_write_binary_ids` note
pointers
This function is always examining its own ELF headers in memory, but it
was trying to use conditions between examining files or memory, and it
wasn't accounting for LOAD offsets at runtime. This is especially bad if
a loaded segment has additional padding that's not in the file offsets.
Now we do a first scan of the program headers to figure out the runtime
base address based on `PT_PHDR` and/or `PT_DYNAMIC` (else assume zero),
similar to libc's `do_start`. Then each `PT_NOTE` pointer is simply the
base plus the segments's `pt_vaddr`, which includes LOAD offsets.
Fixes #114605
---
.../lib/profile/InstrProfilingPlatformLinux.c | 40 ++++++++-----------
1 file changed, 16 insertions(+), 24 deletions(-)
diff --git a/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c b/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
index e2c06d51e0c6..c365129a0768 100644
--- a/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
+++ b/compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
@@ -194,41 +194,33 @@ static int WriteBinaryIds(ProfDataWriter *Writer, const ElfW(Nhdr) * Note,
*/
COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
extern const ElfW(Ehdr) __ehdr_start __attribute__((visibility("hidden")));
+ extern ElfW(Dyn) _DYNAMIC[] __attribute__((weak, visibility("hidden")));
+
const ElfW(Ehdr) *ElfHeader = &__ehdr_start;
const ElfW(Phdr) *ProgramHeader =
(const ElfW(Phdr) *)((uintptr_t)ElfHeader + ElfHeader->e_phoff);
+ /* Compute the added base address in case of position-independent code. */
+ uintptr_t Base = 0;
+ for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
+ if (ProgramHeader[I].p_type == PT_PHDR)
+ Base = (uintptr_t)ProgramHeader - ProgramHeader[I].p_vaddr;
+ if (ProgramHeader[I].p_type == PT_DYNAMIC && _DYNAMIC)
+ Base = (uintptr_t)_DYNAMIC - ProgramHeader[I].p_vaddr;
+ }
+
int TotalBinaryIdsSize = 0;
- uint32_t I;
/* Iterate through entries in the program header. */
- for (I = 0; I < ElfHeader->e_phnum; I++) {
+ for (uint32_t I = 0; I < ElfHeader->e_phnum; I++) {
/* Look for the notes segment in program header entries. */
if (ProgramHeader[I].p_type != PT_NOTE)
continue;
/* There can be multiple notes segment, and examine each of them. */
- const ElfW(Nhdr) * Note;
- const ElfW(Nhdr) * NotesEnd;
- /*
- * When examining notes in file, use p_offset, which is the offset within
- * the elf file, to find the start of notes.
- */
- if (ProgramHeader[I].p_memsz == 0 ||
- ProgramHeader[I].p_memsz == ProgramHeader[I].p_filesz) {
- Note = (const ElfW(Nhdr) *)((uintptr_t)ElfHeader +
- ProgramHeader[I].p_offset);
- NotesEnd = (const ElfW(Nhdr) *)((const char *)(Note) +
- ProgramHeader[I].p_filesz);
- } else {
- /*
- * When examining notes in memory, use p_vaddr, which is the address of
- * section after loaded to memory, to find the start of notes.
- */
- Note =
- (const ElfW(Nhdr) *)((uintptr_t)ElfHeader + ProgramHeader[I].p_vaddr);
- NotesEnd =
- (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
- }
+ const ElfW(Nhdr) *Note =
+ (const ElfW(Nhdr) *)(Base + ProgramHeader[I].p_vaddr);
+ const ElfW(Nhdr) *NotesEnd =
+ (const ElfW(Nhdr) *)((const char *)(Note) + ProgramHeader[I].p_memsz);
int BinaryIdsSize = WriteBinaryIds(Writer, Note, NotesEnd);
if (TotalBinaryIdsSize == -1)
--
2.47.0

View file

@ -182,7 +182,7 @@
#region main package
Name: %{pkg_name_llvm}
Version: %{maj_ver}.%{min_ver}.%{patch_ver}%{?rc_ver:~rc%{rc_ver}}%{?llvm_snapshot_version_suffix:~%{llvm_snapshot_version_suffix}}
Release: 2%{?dist}
Release: 3%{?dist}
Summary: The Low Level Virtual Machine
License: Apache-2.0 WITH LLVM-exception OR NCSA
@ -277,6 +277,12 @@ Patch501: 0001-Fix-page-size-constant-on-aarch64-and-ppc64le.patch
# Fixes RHEL-49517.
Patch1801: 18-99273.patch
# Fix profiling after a binutils NOTE change.
# https://github.com/llvm/llvm-project/pull/114907
Patch1802: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
Patch1903: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
Patch2001: 0001-profile-Use-base-vaddr-for-__llvm_write_binary_ids-n.patch
%if 0%{?rhel} == 8
%global python3_pkgversion 3.12
%global __python3 /usr/bin/python3.12
@ -2472,6 +2478,9 @@ fi
#region changelog
%changelog
* Mon Nov 18 2024 Josh Stone <jistone@redhat.com> - 19.1.3-3
- Fix profiling after a binutils NOTE change (rhbz#2322754)
* Mon Nov 18 2024 Timm Bäder <tbaeder@redhat.com> - 19.1.3-2
- Install i386 config files on x86_64