diff options
Diffstat (limited to 'arch/mips/mips-vdso-fix-jalr-t9-crash-in-vdso-code.patch')
| -rw-r--r-- | arch/mips/mips-vdso-fix-jalr-t9-crash-in-vdso-code.patch | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/mips/mips-vdso-fix-jalr-t9-crash-in-vdso-code.patch b/arch/mips/mips-vdso-fix-jalr-t9-crash-in-vdso-code.patch new file mode 100644 index 00000000..5eb1f280 --- /dev/null +++ b/arch/mips/mips-vdso-fix-jalr-t9-crash-in-vdso-code.patch @@ -0,0 +1,50 @@ +From 96f71c147809df7880100edeecb197d5d5095206 Mon Sep 17 00:00:00 2001 +From: Victor Kamensky <kamensky@cisco.com> +Date: Fri, 31 Jan 2020 09:39:44 -0800 +Subject: [PATCH] mips: vdso: fix 'jalr $t9' crash in vdso code + +Observed that when kernel is built with Yocto mips64-poky-linux-gcc, +and mips64-poky-linux-gnun32-gcc toolchain, resuling vdso contains +'jalr $t9' instructions in its code and since in vdso case nobody +sets GOT table code crashes when instruction reached. On other hand +observed that when kernel is built mips-poky-linux-gcc toolchain, the +same 'jalr $t9' instruction are replaced with PC relative function +calls using 'bal' instructions. + +The difference boils down to -mrelax-pic-calls and -mexplicit-relocs +gcc options that gets different default values depending on gcc +target triplets and corresponding binutils. -mrelax-pic-calls got +enabled by default only in mips-poky-linux-gcc case. MIPS binuitls +ld relies on R_MIPS_JALR relocation to convert 'jalr $t9' into 'bal' +and such relocation is generated only if -mrelax-pic-calls option +is on. + +Solution call out -mrelax-pic-calls and -mexplicit-relocs options +explicitely while compiling MIPS vdso code. That would get correct +and consitent between different toolchains behavior. + +Reported-by: Bruce Ashfield <bruce.ashfield@gmail.com> +Signed-off-by: Victor Kamensky <kamensky@cisco.com> +Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com> +--- + arch/mips/vdso/Makefile | 4 +++- + 1 file changed, 3 insertions(+), 1 deletion(-) + +diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile +index 996a934ece7d..25b5adee5ade 100644 +--- a/arch/mips/vdso/Makefile ++++ b/arch/mips/vdso/Makefile +@@ -31,7 +31,9 @@ cflags-vdso := $(ccflags-vdso) \ + -O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \ + -fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \ + $(call cc-option, -fno-asynchronous-unwind-tables) \ +- $(call cc-option, -fno-stack-protector) ++ $(call cc-option, -fno-stack-protector) \ ++ $(call cc-option, -mrelax-pic-calls) \ ++ $(call cc-option, -mexplicit-relocs) + aflags-vdso := $(ccflags-vdso) \ + -D__ASSEMBLY__ -Wa,-gdwarf-2 + +-- +2.19.1 + |