This is a note to let you know that I've just added the patch titled
LoongArch: Only allow OBJTOOL & ORC unwinder if toolchain supports -mthin-add-sub
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
loongarch-only-allow-objtool-orc-unwinder-if-toolcha.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit caa9862de683a0591338707ee7f366bd947a8015
Author: Xi Ruoyao <xry111@xxxxxxxxxxx>
Date: Fri Jun 21 10:18:40 2024 +0800
LoongArch: Only allow OBJTOOL & ORC unwinder if toolchain supports -mthin-add-sub
[ Upstream commit 120dd4118e58dbda2ddb1dcf55f3c56cdfe8cee0 ]
GAS <= 2.41 does not support generating R_LARCH_{32,64}_PCREL for
"label - ." and it generates R_LARCH_{ADD,SUB}{32,64} pairs instead.
Objtool cannot handle R_LARCH_{ADD,SUB}{32,64} pair in __jump_table
(static key implementation) and etc. so it will produce some warnings.
This is causing the kernel CI systems to complain everywhere.
For GAS we can check if -mthin-add-sub option is available to know if
R_LARCH_{32,64}_PCREL are supported.
For Clang, we require Clang >= 18 and Clang >= 17 already supports
R_LARCH_{32,64}_PCREL. But unfortunately Clang has some other issues,
so we disable objtool for Clang at present.
Note that __jump_table here is not generated by the compiler, so
-fno-jump-table is completely irrelevant for this issue.
Fixes: cb8a2ef0848c ("LoongArch: Add ORC stack unwinder support")
Closes: https://lore.kernel.org/loongarch/Zl5m1ZlVmGKitAof@yujie-X299/
Closes: https://lore.kernel.org/loongarch/ZlY1gDDPi_mNrwJ1@xxxxxxxxxxxxxxx/
Closes: https://lore.kernel.org/loongarch/1717478006.038663-1-hengqi@xxxxxxxxxxxxxxxxx/
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=816029e06768
Link: https://github.com/llvm/llvm-project/commit/42cb3c6346fc
Signed-off-by: Xi Ruoyao <xry111@xxxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 54ad04dacdee9..d1b94ce58f793 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -138,7 +138,7 @@ config LOONGARCH
select HAVE_LIVEPATCH
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI
- select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
+ select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && !CC_IS_CLANG
select HAVE_PCI
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
@@ -257,6 +257,9 @@ config AS_HAS_EXPLICIT_RELOCS
config AS_HAS_FCSR_CLASS
def_bool $(as-instr,movfcsr2gr \$t0$(comma)\$fcsr0)
+config AS_HAS_THIN_ADD_SUB
+ def_bool $(cc-option,-Wa$(comma)-mthin-add-sub)
+
config AS_HAS_LSX_EXTENSION
def_bool $(as-instr,vld \$vr0$(comma)\$a0$(comma)0)
diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug
index 98d60630c3d4b..8b2ce5b5d43e8 100644
--- a/arch/loongarch/Kconfig.debug
+++ b/arch/loongarch/Kconfig.debug
@@ -28,6 +28,7 @@ config UNWINDER_PROLOGUE
config UNWINDER_ORC
bool "ORC unwinder"
+ depends on HAVE_OBJTOOL
select OBJTOOL
help
This option enables the ORC (Oops Rewind Capability) unwinder for
