After adding encoded fp onto stack to record pt_regs, now the
unwinder have ability to unwind frame through irq.
There is two steps to unwind irq frame and the interrupted frame:
1. When there is an encoded fp on stack, we can get the pt_regs
and unwind frame by (regs->epc) and (regs->s0).
2. To unwind the interrupted frame, there is two possibilities,
we can determine the situation by checking whether the value in
frame->ra position is a fp value.
If there is a fp in ra position:
We are inside a leaf frame and there is only fp on ra position.
Get fp from ra position and get next pc from pt_regs.
Else:
Just get fp and next pc from stack frame.
Stacktrace before this patch:
Call Trace:
...
[<ffffffff800aa692>] __flush_smp_call_function_queue+0xde/0x1fa
[<ffffffff800ab404>] generic_smp_call_function_single_interrupt+0x22/0x2a
[<ffffffff800077b2>] handle_IPI+0xaa/0x108
[<ffffffff803f827e>] riscv_intc_irq+0x56/0x6e
[<ffffffff808d94b6>] generic_handle_arch_irq+0x4c/0x76
[<ffffffff80003ad0>] ret_from_exception+0x0/0xc
Stacktrace after this patch:
Call Trace:
...
[<ffffffff800aa6da>] __flush_smp_call_function_queue+0xde/0x1fa
[<ffffffff800ab44c>] generic_smp_call_function_single_interrupt+0x22/0x2a
[<ffffffff800077fa>] handle_IPI+0xaa/0x108
[<ffffffff803f82c6>] riscv_intc_irq+0x56/0x6e
[<ffffffff808d94fe>] generic_handle_arch_irq+0x4c/0x76
[<ffffffff80003ad0>] ret_from_exception+0x0/0xc
+ [<ffffffff80003d52>] arch_cpu_idle+0x22/0x28
+ [<ffffffff808e23a8>] default_idle_call+0x44/0xee
+ [<ffffffff80056ece>] do_idle+0x116/0x126
+ [<ffffffff8005706e>] cpu_startup_entry+0x36/0x38
+ [<ffffffff808d99ae>] kernel_init+0x0/0x15a
+ [<ffffffff80a007a0>] arch_post_acpi_subsys_init+0x0/0x38
+ [<ffffffff80a0100c>] start_kernel+0x7c4/0x7f2
Signed-off-by: Chen Zhongjin <[email protected]>
---
arch/riscv/kernel/stacktrace.c | 45 ++++++++++++++++++++++++++++------
1 file changed, 38 insertions(+), 7 deletions(-)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index e84e21868a3e..976dc298ab3b 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -16,29 +16,60 @@
#ifdef CONFIG_FRAME_POINTER
+static struct pt_regs *decode_frame_pointer(unsigned long fp)
+{
+ if (!(fp & 0x1))
+ return NULL;
+
+ return (struct pt_regs *)(fp & ~0x1);
+}
+
static int notrace unwind_next(struct unwind_state *state)
{
unsigned long low, high, fp;
struct stackframe *frame;
+ struct pt_regs *regs;
- fp = state->fp;
+ regs = decode_frame_pointer(state->fp);
/* Validate frame pointer */
- low = state->sp + sizeof(struct stackframe);
+ if (regs) {
+ if user_mode(regs)
+ return -1;
+
+ fp = (unsigned long)regs;
+ low = state->sp;
+ } else {
+ fp = state->fp;
+ low = state->sp + sizeof(struct stackframe);
+ }
high = ALIGN(low, THREAD_SIZE);
if (fp < low || fp > high || fp & 0x7)
return -EINVAL;
- /* Unwind stack frame */
frame = (struct stackframe *)fp - 1;
state->sp = fp;
- if (state->regs && state->regs->epc == state->pc &&
- fp & 0x7) {
- state->fp = frame->ra;
- state->pc = state->regs->ra;
+ if (regs) {
+ /* Unwind from irq to interrupted function */
+ state->fp = regs->s0;
+ state->pc = regs->epc;
+ state->regs = regs;
+ } else if (state->regs && state->regs->epc == state->pc) {
+ /* Unwind from interrupted function to caller*/
+ if (frame->ra < low || frame->ra > high) {
+ /* normal function */
+ state->fp = frame->fp;
+ state->pc = frame->ra;
+ } else {
+ /* leaf function */
+ state->fp = frame->ra;
+ state->pc = state->regs->ra;
+ }
+ state->regs = NULL;
} else {
+ /* Unwind from normal stack frame */
state->fp = frame->fp;
state->pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
(unsigned long *)fp - 1);
--
2.17.1