arm64: Add stack dump to exception handler

Some exceptions (like from calling a NULL function pointer) are easier
to narrow down with a dump of the call stack. Let's take a page out of
ARM32's book and add that feature to ARM64 as well. Also change the
output format to two register columns, to make it easier to fit a whole
exception dump on one screen.

Applying to both coreboot and libpayload and syncing the output format
between both back up.

Change-Id: I19768d13d8fa8adb84f0edda2af12f20508eb2db
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/14931
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 26 insertions, 4 deletions

diff --git a/payloads/libpayload/arch/arm64/exception.c b/payloads/libpayload/arch/arm64/exception.c
index 2330a98456..078a7000d3 100644
--- a/payloads/libpayload/arch/arm64/exception.c
+++ b/payloads/libpayload/arch/arm64/exception.c
@@ -60,15 +60,35 @@ static struct exception_handler_info exceptions[EXC_COUNT] = {
 	[EXC_SERROR_ELX_32] = {"_serror_elx_32"},
 };
 
+static void dump_stack(uintptr_t addr, size_t bytes)
+{
+	int i, j;
+	const int words_per_line = 8;
+	uint64_t *ptr = (void *)ALIGN_DOWN(addr, words_per_line * sizeof(*ptr));
+
+	printf("Dumping stack:\n");
+	for (i = bytes / sizeof(*ptr); i >= 0; i -= words_per_line) {
+		printf("%p: ", ptr + i);
+		for (j = i; j < i + words_per_line; j++)
+			printf("%016llx ", *(ptr + j));
+		printf("\n");
+	}
+}
+
 static void print_regs(struct exception_state *state)
 {
 	int i;
 
-	printf("ELR = 0x%016llx\n",state->elr);
-	printf("ESR = 0x%08llx\n",state->esr);
-	for (i = 0; i < 31; i++) {
-		printf("X%02d = 0x%016llx\n", i, state->regs[i]);
+	printf("ELR = 0x%016llx         ESR = 0x%08llx\n",
+	       state->elr, state->esr);
+	printf("FAR = 0x%016llx        SPSR = 0x%08x\n",
+	       raw_read_far_current(), raw_read_spsr_current());
+	for (i = 0; i < 30; i += 2) {
+		printf("X%02d = 0x%016llx         X%02d = 0x%016llx\n",
+		       i, state->regs[i], i + 1, state->regs[i + 1]);
 	}
+	printf("X30 = 0x%016llx          SP = 0x%016llx\n",
+	       state->regs[30], raw_read_sp_el0());
 }
 
 void exception_dispatch(struct exception_state *state, int idx);
@@ -89,6 +109,8 @@ void exception_dispatch(struct exception_state *state, int idx)
 			printf("exception _not_used.\n");
 	}
 	print_regs(state);
+	/* Few words below SP in case we need state from a returned function. */
+	dump_stack(raw_read_sp_el0() - 32, 512);
 
 	if (test_exc) {
 		state->elr += 4;