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, 28 insertions, 10 deletions

diff --git a/src/arch/arm64/armv8/exception.c b/src/arch/arm64/armv8/exception.c
index b872a55a8a..c5cbbfea3b 100644
--- a/src/arch/arm64/armv8/exception.c
+++ b/src/arch/arm64/armv8/exception.c
@@ -57,22 +57,38 @@ static const char *exception_names[NUM_EXC_VIDS] = {
 	[EXC_VID_LOW32_SERR] = "_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));
+
+	printk(BIOS_DEBUG, "Dumping stack:\n");
+	for (i = bytes / sizeof(*ptr); i >= 0; i -= words_per_line) {
+		printk(BIOS_DEBUG, "%p: ", ptr + i);
+		for (j = i; j < i + words_per_line; j++)
+			printk(BIOS_DEBUG, "%016llx ", *(ptr + j));
+		printk(BIOS_DEBUG, "\n");
+	}
+}
+
 static void print_regs(struct exc_state *exc_state)
 {
 	int i;
 	struct elx_state *elx = &exc_state->elx;
 	struct regs *regs = &exc_state->regs;
 
-	uint64_t elx_esr = raw_read_esr_current();
-	uint64_t elx_far = raw_read_far_current();
-
-	printk(BIOS_DEBUG, "ELR = 0x%016llx\n", elx->elr);
-	printk(BIOS_DEBUG, "ESR = 0x%016llx\n", elx_esr);
-	printk(BIOS_DEBUG, "SPSR = 0x%08llx\n", elx->spsr);
-	printk(BIOS_DEBUG, "FAR = 0x%016llx\n", elx_far);
-	printk(BIOS_DEBUG, "SP = 0x%016llx\n", regs->sp);
-	for (i = X0_INDEX; i < XMAX_INDEX; i++)
-		printk(BIOS_DEBUG, "X%02d = 0x%016llx\n", i, regs->x[i]);
+	printk(BIOS_DEBUG, "ELR = 0x%016llx         ESR = 0x%08x\n",
+	       elx->elr, raw_read_esr_current());
+	printk(BIOS_DEBUG, "FAR = 0x%016llx        SPSR = 0x%08x\n",
+	       raw_read_far_current(), raw_read_spsr_current());
+	for (i = 0; i < 30; i += 2) {
+		printk(BIOS_DEBUG,
+		       "X%02d = 0x%016llx         X%02d = 0x%016llx\n",
+		       i, regs->x[i], i + 1, regs->x[i + 1]);
+	}
+	printk(BIOS_DEBUG, "X30 = 0x%016llx          SP = 0x%016llx\n",
+	       regs->x[30], regs->sp);
 }
 
 
@@ -119,6 +135,8 @@ static void print_exception_info(struct exc_state *state, uint64_t idx)
 		printk(BIOS_DEBUG, "exception %s\n", exception_names[idx]);
 
 	print_regs(state);
+	/* Few words below SP in case we need state from a returned function. */
+	dump_stack(state->regs.sp - 32, 512);
 }
 
 static void print_exception_and_die(struct exc_state *state, uint64_t idx)