On 2021-07-30, Nick Desaulniers wrote:
On Fri, Jul 30, 2021 at 3:38 PM Nathan Chancellor nathan@kernel.org 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'
^ .text.tsan.*
I was wondering why the orphan section warning only arose recently. Now I see: the function asan.module_ctor has the SHF_GNU_RETAIN flag, so it is in a separate section even with -fno-function-sections (default).
It seems that with -ffunction-sections the issue should have been caught much earlier.
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/7b789562244ee941b7bf2cefeb3fc08a... Signed-off-by: Nathan Chancellor nathan@kernel.org
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..3b79b1e76556 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.asan.*) \Will this match .text.tsan.module_ctor?
asan.module_ctor is the only function AddressSanitizer synthesizes in the instrumented translation unit. There is no function called "asan".
(Even if a function "asan" exists due to -ffunction-sections -funique-section-names, TEXT_MAIN will match .text.asan, so the .text.asan pattern will match nothing.)
Do we want to add these conditionally on CONFIG_KASAN_GENERIC/CONFIG_KCSAN like we do for SANITIZER_DISCARDS?
TEXT_CFI_JT \ MEM_KEEP(init.text*) \ MEM_KEEP(exit.text*) \base-commit: 4669e13cd67f8532be12815ed3d37e775a9bdc16
-- Thanks, ~Nick Desaulniers