diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2022-09-15 13:11:18 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-17 16:41:10 +0200 |
| commit | bea75b33895f7f87f0c40023e36a2d087e87ffa1 (patch) | |
| tree | 301d9fc0cc4db3df6746e8163186cab5bf436632 /arch/x86/Makefile | |
| parent | 8f7c0d8b23c3f5f740a48db31ebadef28af17a22 (diff) | |
x86/Kconfig: Introduce function padding
Now that all functions are 16 byte aligned, add 16 bytes of NOP
padding in front of each function. This prepares things for software
call stack tracking and kCFI/FineIBT.
This significantly increases kernel .text size, around 5.1% on a
x86_64-defconfig-ish build.
However, per the random access argument used for alignment, these 16
extra bytes are code that wouldn't be used. Performance measurements
back this up by showing no significant performance regressions.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.950884492@infradead.org
Diffstat (limited to 'arch/x86/Makefile')
| -rw-r--r-- | arch/x86/Makefile | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 415a5d138de4..1640e005092b 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -208,6 +208,12 @@ ifdef CONFIG_SLS KBUILD_CFLAGS += -mharden-sls=all endif +ifdef CONFIG_CALL_THUNKS +PADDING_CFLAGS := -fpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES) +KBUILD_CFLAGS += $(PADDING_CFLAGS) +export PADDING_CFLAGS +endif + KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) ifdef CONFIG_LTO_CLANG |