[Crash-utility] Problem in bt for ARM64
AKASHI Takahiro
takahiro.akashi at linaro.org
Fri Oct 13 08:29:12 UTC 2017
Dave,
On Fri, Sep 22, 2017 at 03:06:00PM -0400, Dave Anderson wrote:
>
> Jan,
>
> I went back to creating a machdep->machspec->user_eframe_offset value
> to be able to account for both the 4.7 and the upcoming 4.14 pt_regs
> changes:
>
> https://github.com/crash-utility/crash/commit/c975008e61121ef8785622c3bc26964da8fe0deb
>
> Again, though, note that "bt" does not work with 4.14.
Even with your latest changes in 7.2.0, "bt" still has some issues:
a.register dump at exception frame doesn't have correct values
(due to added stackframe[] in pt_regs)
b. tracing irq stack to process stack fails
(due to irq-stack implementation changes and VMAP_STACK)
c."bt -o" seems to have been broken for a while
Attached is my tentative patch, which hopefully addresses (a) and (b).
While it is still far from perfect, it may help give you a heads-up.
Thanks,
-Takahiro AKASHI
===8<===
>From 156ec115b2a436a0738908153d676f8eeed84cb1 Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <takahiro.akashi at linaro.org>
Date: Thu, 12 Oct 2017 10:46:34 +0900
Subject: [PATCH] arm64: backtrace for v4.14
---
arm64.c | 172 ++++++++++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 136 insertions(+), 36 deletions(-)
diff --git a/arm64.c b/arm64.c
index 20c5d34..22c8556 100644
--- a/arm64.c
+++ b/arm64.c
@@ -72,6 +72,7 @@ static void arm64_cmd_mach(void);
static void arm64_display_machine_stats(void);
static int arm64_get_smp_cpus(void);
static void arm64_clear_machdep_cache(void);
+static int arm64_on_process_stack(struct bt_info *, ulong);
static int arm64_in_alternate_stack(int, ulong);
static int arm64_on_irq_stack(int, ulong);
static void arm64_set_irq_stack(struct bt_info *);
@@ -1336,29 +1337,60 @@ arm64_irq_stack_init(void)
req = &request;
struct machine_specific *ms = machdep->machspec;
- if (!symbol_exists("irq_stack") ||
- !(sp = per_cpu_symbol_search("irq_stack")) ||
- !get_symbol_type("irq_stack", NULL, req) ||
- (req->typecode != TYPE_CODE_ARRAY) ||
- (req->target_typecode != TYPE_CODE_INT))
- return;
+ if (!(ms->irq_stacks = (ulong *)malloc((size_t)(kt->cpus
+ * sizeof(ulong)))))
+ error(FATAL, "cannot malloc irq_stack addresses\n");
- if (CRASHDEBUG(1)) {
- fprintf(fp, "irq_stack: \n");
- fprintf(fp, " type: %s\n",
- (req->typecode == TYPE_CODE_ARRAY) ? "TYPE_CODE_ARRAY" : "other");
- fprintf(fp, " target_typecode: %s\n",
- req->target_typecode == TYPE_CODE_INT ? "TYPE_CODE_INT" : "other");
- fprintf(fp, " target_length: %ld\n", req->target_length);
- fprintf(fp, " length: %ld\n", req->length);
- }
+ if (symbol_exists("irq_stack") &&
+ (sp = per_cpu_symbol_search("irq_stack")) &&
+ get_symbol_type("irq_stack", NULL, req)) {
+ /* before v4.14 or CONFIG_VMAP_STACK disabled */
+ if (CRASHDEBUG(1)) {
+ fprintf(fp, "irq_stack: \n");
+ fprintf(fp, " type: %s\n",
+ (req->typecode == TYPE_CODE_ARRAY) ?
+ "TYPE_CODE_ARRAY" : "other");
+ fprintf(fp, " target_typecode: %s\n",
+ req->target_typecode == TYPE_CODE_INT ?
+ "TYPE_CODE_INT" : "other");
+ fprintf(fp, " target_length: %ld\n",
+ req->target_length);
+ fprintf(fp, " length: %ld\n", req->length);
+ }
- ms->irq_stack_size = req->length;
- if (!(ms->irq_stacks = (ulong *)malloc((size_t)(kt->cpus * sizeof(ulong)))))
- error(FATAL, "cannot malloc irq_stack addresses\n");
+ ms->irq_stack_size = req->length;
+
+ for (i = 0; i < kt->cpus; i++)
+ ms->irq_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
+ } else if (symbol_exists("irq_stack_ptr") &&
+ (sp = per_cpu_symbol_search("irq_stack_ptr")) &&
+ get_symbol_type("irq_stack_ptr", NULL, req)) {
+ /* v4.14 and later with CONFIG_VMAP_STACK enabled */
+ if (CRASHDEBUG(1)) {
+ fprintf(fp, "irq_stack_ptr: \n");
+ fprintf(fp, " type: %x, %s\n",
+ (int)req->typecode,
+ (req->typecode == TYPE_CODE_PTR) ?
+ "TYPE_CODE_PTR" : "other");
+ fprintf(fp, " target_typecode: %x, %s\n",
+ (int)req->target_typecode,
+ req->target_typecode == TYPE_CODE_INT ?
+ "TYPE_CODE_INT" : "other");
+ fprintf(fp, " target_length: %ld\n",
+ req->target_length);
+ fprintf(fp, " length: %ld\n", req->length);
+ }
+
+ ms->irq_stack_size = 16384;
+
+ for (i = 0; i < kt->cpus; i++) {
+ ulong p;
- for (i = 0; i < kt->cpus; i++)
- ms->irq_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
+ p = kt->__per_cpu_offset[i] + sp->value;
+ readmem(p, KVADDR, &(ms->irq_stacks[i]), sizeof(ulong),
+ "IRQ stack pointer", RETURN_ON_ERROR);
+ }
+ }
machdep->flags |= IRQ_STACKS;
}
@@ -1750,11 +1782,20 @@ arm64_display_full_frame(struct bt_info *bt, ulong sp)
if (bt->frameptr == sp)
return;
- if (!INSTACK(sp, bt) || !INSTACK(bt->frameptr, bt)) {
- if (sp == 0)
- sp = bt->stacktop - USER_EFRAME_OFFSET;
- else
- return;
+ if (INSTACK(bt->frameptr, bt)) {
+ if (INSTACK(sp, bt)) {
+ /* normal case */;
+ } else {
+ if (sp == 0)
+ /* interrupt in user mode */
+ sp = bt->stacktop - USER_EFRAME_OFFSET;
+ else
+ /* interrupt in kernel mode */
+ sp = bt->stacktop;
+ }
+ } else {
+ error(WARNING, "full display ?\n");
+ return;
}
words = (sp - bt->frameptr) / sizeof(ulong);
@@ -1873,6 +1914,25 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
* orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr); (pt_regs pointer on process stack)
*/
if (machdep->flags & IRQ_STACKS) {
+ if (machdep->flags & UNW_4_14) {
+ if ((bt->flags & BT_IRQSTACK) &&
+ !arm64_on_irq_stack(bt->tc->processor, frame->fp)) {
+ if (arm64_on_process_stack(bt, frame->fp)) {
+ arm64_set_process_stack(bt);
+
+ frame->sp = frame->fp - SIZE(pt_regs) + 16;
+ /* for switch_stack */
+ /* fp still points to irq stack */
+ bt->bptr = fp;
+ /* for display_full_frame */
+ /* sp points to process stack */
+ bt->frameptr = frame->sp;
+ } else {
+ /* irq -> user */
+ return FALSE;
+ }
+ }
+ } else { /* !UNW_4_14 */
ms = machdep->machspec;
irq_stack_ptr = ms->irq_stacks[bt->tc->processor] + ms->irq_stack_size - 16;
@@ -1896,6 +1956,7 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
return FALSE;
}
}
+ } /* UNW_4_14 */
}
return TRUE;
@@ -2086,10 +2147,17 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct arm64_stackframe *frame,
* We are on process stack. Just add a faked frame
*/
- if (!arm64_on_irq_stack(bt->tc->processor, ext_frame.fp))
- frame->sp = ext_frame.fp
- - sizeof(struct arm64_pt_regs);
- else {
+ if (!arm64_on_irq_stack(bt->tc->processor, ext_frame.fp)) {
+ if (MEMBER_EXISTS("pt_regs", "stackframe")) {
+ frame->sp = ext_frame.fp
+ - sizeof(struct arm64_pt_regs) - 16;
+ frame->fp = ext_frame.fp;
+ } else {
+ frame->sp = ext_frame.fp
+ - sizeof(struct arm64_pt_regs);
+ frame->fp = frame->sp;
+ }
+ } else {
/*
* FIXME: very exceptional case
* We are already back on process stack, but
@@ -2109,10 +2177,10 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct arm64_stackframe *frame,
* Really ugly
*/
frame->sp = frame->fp + 0x20;
+ frame->fp = frame->sp;
fprintf(ofp, " (Next exception frame might be wrong)\n");
}
- frame->fp = frame->sp;
} else {
/* We are on IRQ stack */
@@ -2122,9 +2190,15 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct arm64_stackframe *frame,
if (ext_frame.fp != irq_stack_ptr) {
/* (2) Just add a faked frame */
- frame->sp = ext_frame.fp
- - sizeof(struct arm64_pt_regs);
- frame->fp = frame->sp;
+ if (MEMBER_EXISTS("pt_regs", "stackframe")) {
+ frame->sp = ext_frame.fp
+ - sizeof(struct arm64_pt_regs);
+ frame->fp = ext_frame.fp;
+ } else {
+ frame->sp = ext_frame.fp
+ - sizeof(struct arm64_pt_regs) - 16;
+ frame->fp = frame->sp;
+ }
} else {
/*
* (3)
@@ -2304,11 +2378,19 @@ arm64_back_trace_cmd(struct bt_info *bt)
if (arm64_in_exception_text(bt->instptr) && INSTACK(stackframe.fp, bt)) {
if (!(bt->flags & BT_IRQSTACK) ||
(((stackframe.sp + SIZE(pt_regs)) < bt->stacktop)))
- exception_frame = stackframe.fp - SIZE(pt_regs);
+ {
+ if (MEMBER_EXISTS("pt_regs", "stackframe"))
+ /* v4.14 or later */
+ exception_frame = stackframe.fp
+ - SIZE(pt_regs) + 16;
+ else
+ exception_frame = stackframe.fp
+ - SIZE(pt_regs);
+ }
}
if ((bt->flags & BT_IRQSTACK) &&
- !arm64_on_irq_stack(bt->tc->processor, stackframe.sp)) {
+ !arm64_on_irq_stack(bt->tc->processor, stackframe.fp)) {
bt->flags &= ~BT_IRQSTACK;
if (arm64_switch_stack(bt, &stackframe, ofp) == USER_MODE)
break;
@@ -2424,6 +2506,8 @@ user_space:
* otherwise show an exception frame.
* Since exception entry code doesn't have a real
* stackframe, we fake a dummy frame here.
+ * Note: Since we have a real stack frame in pt_regs,
+ * We no longer need a dummy frame on v4.14 or later.
*/
if (!arm64_in_exp_entry(stackframe.pc))
continue;
@@ -2669,7 +2753,9 @@ arm64_switch_stack(struct bt_info *bt, struct arm64_stackframe *frame, FILE *ofp
if (frame->fp == 0)
return USER_MODE;
- arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
+ if (!(machdep->flags & UNW_4_14))
+ arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
+
return KERNEL_MODE;
}
@@ -3362,6 +3448,20 @@ arm64_clear_machdep_cache(void) {
return;
}
+static int
+arm64_on_process_stack(struct bt_info *bt, ulong stkptr)
+{
+ ulong stackbase, stacktop;
+
+ stackbase = GET_STACKBASE(bt->task);
+ stacktop = GET_STACKTOP(bt->task);
+
+ if ((stkptr >= stackbase) && (stkptr < stacktop))
+ return TRUE;
+
+ return FALSE;
+}
+
static int
arm64_on_irq_stack(int cpu, ulong stkptr)
{
--
2.14.1
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