From ad8d41ba596be6c054e5956b145fa223a5bb8b37 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 28 Mar 2017 11:57:27 +0200 Subject: [PATCH] lkdtm: turn off kcov for lkdtm_rodata_do_nothing: [ Upstream commit 7064dc7fc13b2994d33ae540ffb7a3a05ac463bf ] I ran into a link error on ARM64 for lkdtm_rodata_do_nothing: drivers/misc/built-in.o: In function `lkdtm_rodata_do_nothing': :(.rodata+0x68c8): relocation truncated to fit: R_AARCH64_CALL26 against symbol `__sanitizer_cov_trace_pc' defined in .text section in kernel/built-in.o I did not analyze this further, but my theory is that we would need a trampoline to call __sanitizer_cov_trace_pc(), but the linker (correctly) only adds trampolines for callers in executable sections. Disabling KCOV for this one file avoids the build failure with no other practical downsides I can think of. The problem can only happen on kernels that contain both kcov and lkdtm, so if we want to backport this, it should be in the earliest version that has both (v4.8). Fixes: 5c9a8750a640 ("kernel: add kcov code coverage") Fixes: 9a49a528dcf3 ("lkdtm: add function for testing .rodata section") Signed-off-by: Arnd Bergmann Acked-by: Dmitry Vyukov Acked-by: Kees Cook Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/misc/Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 31983366090a..2bf79ba4a39e 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -61,6 +61,8 @@ lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o +KCOV_INSTRUMENT_lkdtm_rodata.o := n + OBJCOPYFLAGS := OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \ --set-section-flags .text=alloc,readonly \ -- 2.11.0