From 8df4e60945fa9efdeab1a2fa2a5cdf22ea9c9112 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Thu, 12 Nov 2020 09:59:43 -0800 Subject: [PATCH] [ELF] Don't consider SHF_ALLOC ".debug*" sections debug sections Fixes PR48071 * The Rust compiler produces SHF_ALLOC `.debug_gdb_scripts` (which normally does not have the flag) * `.debug_gdb_scripts` sections are removed from `inputSections` due to --strip-debug/--strip-all * When processing --gc-sections, pieces of a SHF_MERGE section can be marked live separately `=>` segfault when marking liveness of a `.debug_gdb_scripts` which is not split into pieces (because it is not in `inputSections`) This patch circumvents the problem by not treating SHF_ALLOC ".debug*" as debug sections (to prevent --strip-debug's stripping) (which is still useful on its own). Reviewed By: grimar Differential Revision: https://reviews.llvm.org/D91291 --- lld/ELF/InputSection.h | 3 ++- lld/test/ELF/gc-sections-strip-debug.s | 17 +++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 lld/test/ELF/gc-sections-strip-debug.s diff --git a/lld/ELF/InputSection.h b/lld/ELF/InputSection.h index a8771ba..5b91c1c 100644 --- a/lld/ELF/InputSection.h +++ b/lld/ELF/InputSection.h @@ -397,7 +397,8 @@ static_assert(sizeof(InputSection) <= 184, "InputSection is too big"); #endif inline bool isDebugSection(const InputSectionBase &sec) { - return sec.name.startswith(".debug") || sec.name.startswith(".zdebug"); + return (sec.flags & llvm::ELF::SHF_ALLOC) == 0 && + (sec.name.startswith(".debug") || sec.name.startswith(".zdebug")); } // The list of all input sections. diff --git a/lld/test/ELF/gc-sections-strip-debug.s b/lld/test/ELF/gc-sections-strip-debug.s new file mode 100644 index 0000000..e7a5fc0 --- /dev/null +++ b/lld/test/ELF/gc-sections-strip-debug.s @@ -0,0 +1,17 @@ +# REQUIRES: x86 +## Test that we don't strip SHF_ALLOC .debug* or crash (PR48071 +## mark liveness of a merge section which has not been split). + +# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o +# RUN: ld.lld %t.o --gc-sections --strip-debug -o %t +# RUN: llvm-readelf -S %t | FileCheck %s + +# CHECK: .debug_gdb_scripts + +.globl _start +_start: + leaq .L.str(%rip), %rax + +.section .debug_gdb_scripts,"aMS",@progbits,1 +.L.str: + .asciz "Rust uses SHF_ALLOC .debug_gdb_scripts" -- 2.7.4