On arm64, an exception handler use the same stack as in non-exception contexts, but doesn't create a stack frame for elx_xx entry, only updating sp register. This behavior results in save_stace_trace() missing a function that is the one when an exception happens.
This patch creates a stack frame for this case, and puts an additional entry for the function in a stack trace list. Signed-off-by: AKASHI Takahiro <[email protected]> --- arch/arm64/kernel/entry.S | 4 ++++ arch/arm64/kernel/stacktrace.c | 17 +++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f860bfd..aacb6c6 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -107,6 +107,8 @@ str x21, [sp, #S_SYSCALLNO] .endif + /* create a stack frame for stack tracer */ + mov x29, sp /* * Registers that may be useful after this macro is invoked: * @@ -737,3 +739,5 @@ ENTRY(sys_rt_sigreturn_wrapper) mov x0, sp b sys_rt_sigreturn ENDPROC(sys_rt_sigreturn_wrapper) + +ENTRY(end_of_vectors) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d1790eb..22ce7c9 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -25,6 +25,10 @@ #include <asm/stacktrace.h> #define S_FRAME_SIZE sizeof(struct pt_regs) /* asm-offsets.h */ +#define S_FP offsetof(struct pt_regs, regs[29]) +#define S_LR offsetof(struct pt_regs, regs[30]) + +extern unsigned int *vectors, *end_of_vectors; /* * AArch64 PCS assigns the frame pointer to x29. @@ -50,6 +54,19 @@ int notrace unwind_frame(struct stackframe *frame) if (fp < low || fp > high - 0x18 || fp & 0xf) return -EINVAL; + if ((frame->pc >= (unsigned long)&vectors) && + (frame->pc < (unsigned long)&end_of_vectors)) { + /* + * Expection handler does not use a normal format of + * stack frame, but allocates struct pt_regs. + */ + frame->sp = frame->sp + S_FRAME_SIZE; + frame->fp = *(unsigned long *)(fp + S_FP); + frame->pc = *(unsigned long *)(fp + S_LR); + + return 0; + } + frame->sp = fp + 0x10; frame->fp = *(unsigned long *)(fp); /* -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
