Hi Vaibhav,
What LTS kernel are you basing your distro off of? IIRC, 4.19, or was
it further back?
On Tue, Aug 13, 2019 at 11:40 AM <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch below does not apply to the 4.9-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From b059f801a937d164e03b33c1848bb3dca67c0b04 Mon Sep 17 00:00:00 2001
> From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Date: Wed, 7 Aug 2019 15:15:33 -0700
> Subject: [PATCH] x86/purgatory: Use CFLAGS_REMOVE rather than reset
> KBUILD_CFLAGS
>
> KBUILD_CFLAGS is very carefully built up in the top level Makefile,
> particularly when cross compiling or using different build tools.
> Resetting KBUILD_CFLAGS via := assignment is an antipattern.
>
> The comment above the reset mentions that -pg is problematic. Other
> Makefiles use `CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE)` when
> CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of
> the important KBUILD_CFLAGS then manually having to re-add them. Seems
> also that __stack_chk_fail references are generated when using
> CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.
>
> Fixes: 8fc5b4d4121c ("purgatory: core purgatory functionality")
> Reported-by: Vaibhav Rustagi <vaibhavrustagi@xxxxxxxxxx>
> Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Tested-by: Vaibhav Rustagi <vaibhavrustagi@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Link: https://lkml.kernel.org/r/20190807221539.94583-2-ndesaulniers@xxxxxxxxxx
>
> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> index 91ef244026d2..8901a1f89cf5 100644
> --- a/arch/x86/purgatory/Makefile
> +++ b/arch/x86/purgatory/Makefile
> @@ -20,11 +20,34 @@ KCOV_INSTRUMENT := n
>
> # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
> # in turn leaves some undefined symbols like __fentry__ in purgatory and not
> -# sure how to relocate those. Like kexec-tools, use custom flags.
> -
> -KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large
> -KBUILD_CFLAGS += -m$(BITS)
> -KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
> +# sure how to relocate those.
> +ifdef CONFIG_FUNCTION_TRACER
> +CFLAGS_REMOVE_sha256.o += $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_purgatory.o += $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_string.o += $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_kexec-purgatory.o += $(CC_FLAGS_FTRACE)
> +endif
> +
> +ifdef CONFIG_STACKPROTECTOR
> +CFLAGS_REMOVE_sha256.o += -fstack-protector
> +CFLAGS_REMOVE_purgatory.o += -fstack-protector
> +CFLAGS_REMOVE_string.o += -fstack-protector
> +CFLAGS_REMOVE_kexec-purgatory.o += -fstack-protector
> +endif
> +
> +ifdef CONFIG_STACKPROTECTOR_STRONG
> +CFLAGS_REMOVE_sha256.o += -fstack-protector-strong
> +CFLAGS_REMOVE_purgatory.o += -fstack-protector-strong
> +CFLAGS_REMOVE_string.o += -fstack-protector-strong
> +CFLAGS_REMOVE_kexec-purgatory.o += -fstack-protector-strong
> +endif
> +
> +ifdef CONFIG_RETPOLINE
> +CFLAGS_REMOVE_sha256.o += $(RETPOLINE_CFLAGS)
> +CFLAGS_REMOVE_purgatory.o += $(RETPOLINE_CFLAGS)
> +CFLAGS_REMOVE_string.o += $(RETPOLINE_CFLAGS)
> +CFLAGS_REMOVE_kexec-purgatory.o += $(RETPOLINE_CFLAGS)
> +endif
>
> $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
> $(call if_changed,ld)
>
--
Thanks,
~Nick Desaulniers
