On Wed, Feb 03, 2021 at 09:46:55AM -0800, Ivan Babrou wrote:
> > Can you pretty please not line-wrap console output? It's unreadable.
>
> GMail doesn't make it easy, I'll send a link to a pastebin next time.
> Let me know if you'd like me to regenerate the decoded stack.
>
> > > edfd9b7838ba5e47f19ad8466d0565aba5c59bf0 is the first bad commit
> > > commit edfd9b7838ba5e47f19ad8466d0565aba5c59bf0
> >
> > Not sure what tree you're on, but that's not the upstream commit.
>
> I mentioned that it's a rebased core-static_call-2020-10-12 tag and
> added a link to the upstream hash right below.
>
> > > Author: Steven Rostedt (VMware) <rost...@goodmis.org>
> > > Date: Tue Aug 18 15:57:52 2020 +0200
> > >
> > > tracepoint: Optimize using static_call()
> > >
> >
> > There's a known issue with that patch, can you try:
> >
> > http://lkml.kernel.org/r/20210202220121.435051...@goodmis.org
>
> I've tried it on top of core-static_call-2020-10-12 tag rebased on top
> of v5.9 (to make it reproducible), and the patch did not help. Do I
> need to apply the whole series or something else?
Can you recreate with this patch, and add "unwind_debug" to the cmdline?
It will spit out a bunch of stack data.
From: Josh Poimboeuf <jpoim...@redhat.com>
Subject: [PATCH] Subject: [PATCH] x86/unwind: Add 'unwind_debug' cmdline
option
Sometimes the one-line ORC unwinder warnings aren't very helpful. Take
the existing frame pointer unwind_dump() and make it useful for all
unwinders.
I don't want to be too aggressive about enabling the dumps, so for now
they're only enabled with the use of a new 'unwind_debug' cmdline
option. When enabled, it will dump the full contents of the stack when
an error condition is encountered, or when dump_stack() is called.
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
.../admin-guide/kernel-parameters.txt | 6 +++
arch/x86/include/asm/unwind.h | 3 ++
arch/x86/kernel/dumpstack.c | 39 ++++++++++++++
arch/x86/kernel/unwind_frame.c | 51 +++----------------
arch/x86/kernel/unwind_orc.c | 5 +-
5 files changed, 58 insertions(+), 46 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 3d6604a949f8..d29689aa62a2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5521,6 +5521,12 @@
unknown_nmi_panic
[X86] Cause panic on unknown NMI.
+ unwind_debug [X86-64]
+ Enable unwinder debug output. This can be
+ useful for debugging certain unwinder error
+ conditions, including corrupt stacks and
+ bad/missing unwinder metadata.
+
usbcore.authorized_default=
[USB] Default USB device authorization:
(default -1 = authorized except for wireless USB,
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 70fc159ebe69..5101d7ef7912 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -123,4 +123,7 @@ static inline bool task_on_another_cpu(struct task_struct
*task)
#endif
}
+extern bool unwind_debug __ro_after_init;
+void unwind_dump(struct unwind_state *state);
+
#endif /* _ASM_X86_UNWIND_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 299c20f0a38b..febfd5b7f62a 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -29,6 +29,42 @@ static int die_counter;
static struct pt_regs exec_summary_regs;
+bool unwind_debug __ro_after_init;
+static int __init unwind_debug_cmdline(char *str)
+{
+ unwind_debug = true;
+ return 0;
+}
+early_param("unwind_debug", unwind_debug_cmdline);
+
+void unwind_dump(struct unwind_state *state)
+{
+ unsigned long word, *sp;
+ struct stack_info stack_info = {0};
+ unsigned long visit_mask = 0;
+
+ printk_deferred("unwinder dump: stack type:%d next_sp:%p mask:0x%lx
graph_idx:%d\n",
+ state->stack_info.type, state->stack_info.next_sp,
+ state->stack_mask, state->graph_idx);
+
+ sp = state->task == current ? __builtin_frame_address(0)
+ : (void *)state->task->thread.sp;
+
+ for (; sp; sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
+ if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
+ break;
+
+ for (; sp < stack_info.end; sp++) {
+
+ word = READ_ONCE_NOCHECK(*sp);
+
+ printk_deferred("%0*lx: %0*lx (%pB)\n", BITS_PER_LONG/4,
+ (unsigned long)sp, BITS_PER_LONG/4,
+ word, (void *)word);
+ }
+ }
+}
+
bool noinstr in_task_stack(unsigned long *stack, struct task_struct *task,
struct stack_info *info)
{
@@ -301,6 +337,9 @@ static void show_trace_log_lvl(struct task_struct *task,
struct pt_regs *regs,
if (stack_name)
printk("%s </%s>\n", log_lvl, stack_name);
}
+
+ if (unwind_debug)
+ unwind_dump(&state);
}
void show_stack(struct task_struct *task, unsigned long *sp,
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index d7c44b257f7f..6bcdf6ecad65 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -28,48 +28,6 @@ unsigned long *unwind_get_return_address_ptr(struct
unwind_state *state)
return state->regs ? &state->regs->ip : state->bp + 1;
}
-static void unwind_dump(struct unwind_state *state)
-{
- static bool dumped_before = false;
- bool prev_zero, zero = false;
- unsigned long word, *sp;
- struct stack_info stack_info = {0};
- unsigned long visit_mask = 0;
-
- if (dumped_before)
- return;
-
- dumped_before = true;
-
- printk_deferred("unwind stack type:%d next_sp:%p mask:0x%lx
graph_idx:%d\n",
- state->stack_info.type, state->stack_info.next_sp,
- state->stack_mask, state->graph_idx);
-
- for (sp = PTR_ALIGN(state->orig_sp, sizeof(long)); sp;
- sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
- if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
- break;
-
- for (; sp < stack_info.end; sp++) {
-
- word = READ_ONCE_NOCHECK(*sp);
-
- prev_zero = zero;
- zero = word == 0;
-
- if (zero) {
- if (!prev_zero)
- printk_deferred("%p: %0*x ...\n",
- sp, BITS_PER_LONG/4, 0);
- continue;
- }
-
- printk_deferred("%p: %0*lx (%pB)\n",
- sp, BITS_PER_LONG/4, word, (void
*)word);
- }
- }
-}
-
static bool in_entry_code(unsigned long ip)
{
char *addr = (char *)ip;
@@ -244,7 +202,6 @@ static bool update_stack_state(struct unwind_state *state,
addr, addr_p);
}
- /* Save the original stack pointer for unwind_dump(): */
if (!state->orig_sp)
state->orig_sp = frame;
@@ -346,13 +303,17 @@ bool unwind_next_frame(struct unwind_state *state)
"WARNING: kernel stack regs at %p in %s:%d has bad 'bp'
value %p\n",
state->regs, state->task->comm,
state->task->pid, next_bp);
- unwind_dump(state);
+
+ if (unwind_debug)
+ unwind_dump(state);
} else {
printk_deferred_once(KERN_WARNING
"WARNING: kernel stack frame pointer at %p in %s:%d has
bad value %p\n",
state->bp, state->task->comm,
state->task->pid, next_bp);
- unwind_dump(state);
+
+ if (unwind_debug)
+ unwind_dump(state);
}
the_end:
state->stack_info.type = STACK_TYPE_UNKNOWN;
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 73f800100066..38265eac41dd 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -13,8 +13,11 @@
#define orc_warn_current(args...) \
({ \
- if (state->task == current) \
+ if (state->task == current) { \
orc_warn(args); \
+ if (unwind_debug) \
+ unwind_dump(state); \
+ } \
})
extern int __start_orc_unwind_ip[];
--
2.29.2
