Hi all, After merging the akpm-current tree, today's linux-next build (arm64 defconfig) failed like this: In file included from include/asm-generic/percpu.h:7, from arch/arm64/include/asm/percpu.h:248, from include/linux/irqflags.h:17, from include/linux/spinlock.h:58, from include/linux/irq.h:14, from arch/arm64/kernel/irq.c:13: arch/arm64/kernel/irq.c: In function 'init_irq_scs': arch/arm64/kernel/irq.c:44:25: error: 'irq_shadow_call_stack_ptr' undeclared (first use in this function) 44 | per_cpu(irq_shadow_call_stack_ptr, cpu) = | ^~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/percpu-defs.h:219:54: note: in definition of macro '__verify_pcpu_ptr' 219 | const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \ | ^~~ include/linux/percpu-defs.h:269:35: note: in expansion of macro 'per_cpu_ptr' 269 | #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu)) | ^~~~~~~~~~~ arch/arm64/kernel/irq.c:44:17: note: in expansion of macro 'per_cpu' 44 | per_cpu(irq_shadow_call_stack_ptr, cpu) = | ^~~~~~~ arch/arm64/kernel/irq.c:44:25: note: each undeclared identifier is reported only once for each function it appears in 44 | per_cpu(irq_shadow_call_stack_ptr, cpu) = | ^~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/percpu-defs.h:219:54: note: in definition of macro '__verify_pcpu_ptr' 219 | const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \ | ^~~ include/linux/percpu-defs.h:269:35: note: in expansion of macro 'per_cpu_ptr' 269 | #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu)) | ^~~~~~~~~~~ arch/arm64/kernel/irq.c:44:17: note: in expansion of macro 'per_cpu' 44 | per_cpu(irq_shadow_call_stack_ptr, cpu) = | ^~~~~~~ Caused by commit aa0120feb340 ("arm64, scs: save scs_sp values per-cpu when switching stacks") I have applied the following patch for today. From: Stephen Rothwell Date: Thu, 31 Mar 2022 13:33:55 +1100 Subject: [PATCH] fix up for "arm64, scs: save scs_sp values per-cpu when switching stacks" Signed-off-by: Stephen Rothwell --- arch/arm64/kernel/irq.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index 4199f900714a..5a15e6a42cbf 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -22,6 +22,7 @@ #include #include #include +#include /* Only access this in an NMI enter/exit */ DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts); -- 2.35.1 This then produced the following: arch/arm64/kernel/stacktrace.c: In function 'arch_stack_walk_shadow': arch/arm64/kernel/stacktrace.c:289:20: error: implicit declaration of function 'task_scs'; did you mean 'task_lock'? [-Werror=implicit-function-declaration] 289 | scs_base = task_scs(current); | ^~~~~~~~ | task_lock arch/arm64/kernel/stacktrace.c:289:18: warning: assignment to 'long unsigned int *' from 'int' makes pointer from integer without a cast [-Wint-conversion] 289 | scs_base = task_scs(current); | ^ I assume this has never been compiled with CONFIG_SHADOW_CALL_STACK not set :-( I have reverted these commits for today: 5c6df774c321 kasan: use stack_trace_save_shadow 0f63d30c44d6 arm64: implement stack_trace_save_shadow aa0120feb340 arm64, scs: save scs_sp values per-cpu when switching stacks 636fecb8f05e stacktrace: add interface based on shadow call stack -- Cheers, Stephen Rothwell