[PATCH] arm64: kconfig: Update and comment GCC version check for kernel BTI

[PATCH] arm64: kconfig: Update and comment GCC version check for kernel BTI

[Will Deacon]

Some versions of GCC are known to suffer from a BTI code generation bug,
meaning that CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI cannot be solely used
to determine whether or not we can compile with kernel with BTI enabled.

Update the BTI Kconfig entry to refer to the relevant GCC bugzilla entry
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697) and update the check
now that the fix has been merged into GCC release 10.1.

Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 77d5fa96f9d0..e058854bcefc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1616,7 +1616,8 @@ config ARM64_BTI_KERNEL
 	depends on ARM64_BTI
 	depends on ARM64_PTR_AUTH
 	depends on CC_HAS_BRANCH_PROT_PAC_RET_BTI
-	depends on !CC_IS_GCC || GCC_VERSION >= 100000
+	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697
+	depends on !CC_IS_GCC || GCC_VERSION >= 100100
 	depends on !(CC_IS_CLANG && GCOV_KERNEL)
 	depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
 	help
-- 
2.26.2.645.ge9eca65c58-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm64: kconfig: Update and comment GCC version check for kernel BTI

[Mark Brown]

[-- Attachment #1.1: Type: text/plain, Size: 661 bytes --]

On Tue, May 12, 2020 at 12:54:58PM +0100, Will Deacon wrote:
> Some versions of GCC are known to suffer from a BTI code generation bug,
> meaning that CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI cannot be solely used
> to determine whether or not we can compile with kernel with BTI enabled.
> 
> Update the BTI Kconfig entry to refer to the relevant GCC bugzilla entry
> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697) and update the check
> now that the fix has been merged into GCC release 10.1.

Acked-by: Mark Brown <broonie@kernel.org>

There wasn't a GCC 10.0 release, I was a little surprised at the
numbering of the initial GCC 10 release.

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel