From 003fc928374cf9a56903d50607695ec94d8adb06 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 23 May 2022 21:16:20 +0800 Subject: [PATCH] kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled stable inclusion from stable-v5.10.102 commit 44b81136e86849117f34a083c359e4860662b3be bugzilla: https://gitee.com/openeuler/kernel/issues/I567K6 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=44b81136e86849117f34a083c359e4860662b3be -------------------------------- commit 6a3193cdd5e5b96ac65f04ee42555c216da332af upstream. Merge module sections only when using Clang LTO. With ld.bfd, merging sections does not appear to update the symbol tables for the module, e.g. 'readelf -s' shows the value that a symbol would have had, if sections were not merged. ld.lld does not show this problem. The stale symbol table breaks gdb's function disassembler, and presumably other things, e.g. gdb -batch -ex "file arch/x86/kvm/kvm.ko" -ex "disassemble kvm_init" reads the wrong bytes and dumps garbage. Fixes: dd2776222abb ("kbuild: lto: merge module sections") Cc: Nick Desaulniers Signed-off-by: Sean Christopherson Reviewed-by: Sami Tolvanen Tested-by: Sami Tolvanen Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210322234438.502582-1-seanjc@google.com Cc: Stephen Boyd Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yu Liao Reviewed-by: Wei Li Signed-off-by: Zheng Zengkai --- scripts/module.lds.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/scripts/module.lds.S b/scripts/module.lds.S index 29bc24d5c906..c86ce15bca16 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -27,6 +27,7 @@ SECTIONS { __patchable_function_entries : { *(__patchable_function_entries) } +#ifdef CONFIG_LTO_CLANG /* * With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and * -ffunction-sections, which increases the size of the final module. @@ -48,6 +49,7 @@ SECTIONS { } .text : { *(.text .text.[0-9a-zA-Z_]*) } +#endif } /* bring in arch-specific sections */ -- GitLab