6.14-stable review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 93f16a1ab78ca56e3cd997d1ea54c214774781ac ]
The handoff between the boot stubs and start_secondary() are before IBT is enabled and is definitely not subject to kCFI. As such, suppress all that for this function.
Notably when the ENDBR poison would become fatal (ud1 instead of nop) this will trigger a tripple fault because we haven't set up the IDT to handle #UD yet.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Sami Tolvanen samitolvanen@google.com Link: https://lore.kernel.org/r/20250207122546.509520369@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/smpboot.c | 3 ++- include/linux/objtool.h | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 3d5069ee297bf..463634b138bbb 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -229,7 +229,7 @@ static void ap_calibrate_delay(void) /* * Activate a secondary processor. */ -static void notrace start_secondary(void *unused) +static void notrace __noendbr start_secondary(void *unused) { /* * Don't put *anything* except direct CPU state initialization @@ -314,6 +314,7 @@ static void notrace start_secondary(void *unused) wmb(); cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); } +ANNOTATE_NOENDBR_SYM(start_secondary);
/* * The bootstrap kernel entry code has set these up. Save them for diff --git a/include/linux/objtool.h b/include/linux/objtool.h index c722a921165ba..3ca965a2ddc80 100644 --- a/include/linux/objtool.h +++ b/include/linux/objtool.h @@ -128,7 +128,7 @@ #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t" #define STACK_FRAME_NON_STANDARD(func) #define STACK_FRAME_NON_STANDARD_FP(func) -#define __ASM_ANNOTATE(label, type) +#define __ASM_ANNOTATE(label, type) "" #define ASM_ANNOTATE(type) #else .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 @@ -147,6 +147,8 @@ * these relocations will never be used for indirect calls. */ #define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR) +#define ANNOTATE_NOENDBR_SYM(sym) asm(__ASM_ANNOTATE(sym, ANNOTYPE_NOENDBR)) + /* * This should be used immediately before an indirect jump/call. It tells * objtool the subsequent indirect jump/call is vouched safe for retpoline