From: Weinan Liu <[email protected]> DWARF CFI (Call Frame Information) specifies how to recover the return address and callee-saved registers at each PC in a given function. Compilers are able to generate the CFI annotations when they compile the code to assembly language. For handcrafted assembly, we need to annotate them by hand.
Frame pointers alone are usually sufficient to recover stack frames (without CFI), except at the exception boundary, where more information is needed to determine if the LR is live. Since an exception can be taken from call_on_irq_stack(), annotate it with CFI. The actual entry assembly functions are left untouched, since they are not expected to take exceptions themselves. Signed-off-by: Weinan Liu <[email protected]> Suggested-by: Jens Remus <[email protected]> Reviewed-by: Jens Remus <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- arch/arm64/kernel/entry.S | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e0db14e9c843..5f4172ba4274 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -30,6 +30,12 @@ #include <asm/asm-uaccess.h> #include <asm/unistd.h> +/* + * Do not generate .eh_frame. Only generate .debug_frame and optionally + * .sframe (via assembler option --gsframe[-N]). + */ + .cfi_sections .debug_frame + .macro clear_gp_regs .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 mov x\n, xzr @@ -870,6 +876,7 @@ NOKPROBE(ret_from_fork) * Calls func(regs) using this CPU's irq stack and shadow irq stack. */ SYM_FUNC_START(call_on_irq_stack) + .cfi_startproc save_and_disable_daif x9 #ifdef CONFIG_SHADOW_CALL_STACK get_current_task x16 @@ -880,6 +887,9 @@ SYM_FUNC_START(call_on_irq_stack) /* Create a frame record to save our LR and SP (implicit in FP) */ stp x29, x30, [sp, #-16]! mov x29, sp + .cfi_def_cfa 29, 16 + .cfi_offset 29, -16 + .cfi_offset 30, -8 ldr_this_cpu x16, irq_stack_ptr, x17 @@ -895,9 +905,13 @@ SYM_FUNC_START(call_on_irq_stack) */ mov sp, x29 ldp x29, x30, [sp], #16 + .cfi_restore 29 + .cfi_restore 30 + .cfi_def_cfa 31, 0 scs_load_current restore_irq x9 ret + .cfi_endproc SYM_FUNC_END(call_on_irq_stack) NOKPROBE(call_on_irq_stack) -- 2.54.0.563.g4f69b47b94-goog
