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SubjectRe: Linux 5.8-rc1
On Tue, Jun 16, 2020 at 10:11:46PM +0200, Gabriel C wrote:
> * Am So., 14. Juni 2020 um 22:44 Uhr schrieb Linus Torvalds
> <torvalds@linux-foundation.org>:
>
> Hello,
>
> > So I didn't really expect this, but 5.8 looks to be one of our biggest
> > releases of all time.
> >
>
> I hit a compiler error caused by e4160b2e4b02377c67f8ecd05786811598f39acd.
>
> x86/purgatory: Fail the build if purgatory.ro has missing symbols
>
> Having CONFIG_STACKPROTECTOR* & CONFIG_KEXEC_FILE enabled always
> results in a linking error like this:
>
> LD arch/x86/purgatory/purgatory.chk
> ld: arch/x86/purgatory/purgatory.ro: in function `verify_sha256_digest':
> purgatory.c:(.text+0x108): undefined reference to `__stack_chk_fail'
> ld: arch/x86/purgatory/purgatory.ro: in function `sha256_transform':
> sha256.c:(.text+0x1c74): undefined reference to `__stack_chk_fail'
> ld: arch/x86/purgatory/purgatory.ro: in function `__sha256_final':
> sha256.c:(.text+0x1e65): undefined reference to `__stack_chk_fail'
> ld: arch/x86/purgatory/purgatory.ro: in function `_kstrtoull':
> string.c:(.text+0x2107): undefined reference to `__stack_chk_fail'
>
> I didn't look closer at that but from the error, it seems to be,
> some missing -fstack-protector* vs -fno-stack-protector* checks
> somewhere.
>
>
> Best Regards,
>
> Gabriel C

Can you attach the output of gcc -dumpspecs and gcc -v? I suspect your
compiler enables stack protector by default. My distro compiler does
that too, but not if -ffreestanding is enabled (which it is for the
purgatory).

Does this patch help?

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index b04e6e72a592..088bd764e0b7 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -34,6 +34,7 @@ KCOV_INSTRUMENT := n
PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
+PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)

# 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
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