Re: [PATCH v2] vmlinux.lds.h: Handle clang's module.{c,d}tor sections
From: Nick Desaulniers <hidden>
Date: 2021-08-02 16:41:12
Also in:
lkml, stable
On Fri, Jul 30, 2021 at 7:33 PM Nathan Chancellor [off-list ref] wrote:
A recent change in LLVM causes module_{c,d}tor sections to appear when
CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings
because these are not handled anywhere:
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor'
Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN
flag, so it is in a separate section even with -fno-function-sections
(default)".
Place them in the TEXT_TEXT section so that these technologies continue
to work with the newer compiler versions. All of the KASAN and KCSAN
KUnit tests continue to pass after this change.
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1432
Link: https://github.com/llvm/llvm-project/commit/7b789562244ee941b7bf2cefeb3fc08a59a01865
Signed-off-by: Nathan Chancellor <nathan@kernel.org>Reviewed-by: Nick Desaulniers <redacted>
quoted hunk ↗ jump to hunk
--- v1 -> v2: * Fix inclusion of .text.tsan.* (Nick) * Drop .text.asan as it does not exist plus it would be handled by a different line (Fangrui) * Add Fangrui's explanation about why the LLVM commit caused these sections to appear. include/asm-generic/vmlinux.lds.h | 1 + 1 file changed, 1 insertion(+)diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 17325416e2de..62669b36a772 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h@@ -586,6 +586,7 @@ NOINSTR_TEXT \ *(.text..refcount) \ *(.ref.text) \ + *(.text.asan.* .text.tsan.*) \ TEXT_CFI_JT \ MEM_KEEP(init.text*) \ MEM_KEEP(exit.text*) \base-commit: 4669e13cd67f8532be12815ed3d37e775a9bdc16 -- 2.32.0.264.g75ae10bc75
-- Thanks, ~Nick Desaulniers