From: Song Shuai <songshuaishuai@tinylab.org>
To: xianting.tian@linux.alibaba.com, k-hagio-ab@nec.com,
kexec@lists.infradead.org, crash-utility@redhat.com
Cc: Song Shuai <songshuaishuai@tinylab.org>
Subject: [PATCH 2/2] [Crash-utility] RISCV64: Fix 'bt' output when no ra on the stack top
Date: Mon, 4 Dec 2023 18:50:15 +0800 [thread overview]
Message-ID: <20231204105015.2341055-2-songshuaishuai@tinylab.org> (raw)
In-Reply-To: <20231204105015.2341055-1-songshuaishuai@tinylab.org>
Same as the Linux commit f766f77a74f5 ("riscv/stacktrace: Fix
stack output without ra on the stack top").
When a function doesn't have a callee, then it will not
push ra into the stack, such as lkdtm functions, so
correct the FP of the second frame and use pt_regs to get
the right PC of the second frame.
TEST:
Before this patch, the `bt -f` outputs only the first frame with
the wrong PC and FP of next frame:
```
crash> bt -f
PID: 1 TASK: ff600000000e0000 CPU: 1 COMMAND: "sh"
#0 [ff20000000013cf0] lkdtm_EXCEPTION at ffffffff805303c0
[PC: ffffffff805303c0 RA: ff20000000013d10 SP: ff20000000013cf0 SIZE: 16] <- wrong next PC
ff20000000013cf0: 0000000000000001 ff20000000013d10 <- next FP
ff20000000013d00: ff20000000013d40
crash>
```
After this patch, the `bt` outputs the full frames:
```
crash> bt
PID: 1 TASK: ff600000000e0000 CPU: 1 COMMAND: "sh"
#0 [ff20000000013cf0] lkdtm_EXCEPTION at ffffffff805303c0
#1 [ff20000000013d00] lkdtm_do_action at ffffffff8052fe36
#2 [ff20000000013d10] direct_entry at ffffffff80530018
#3 [ff20000000013d40] full_proxy_write at ffffffff80305044
#4 [ff20000000013d80] vfs_write at ffffffff801b68b4
#5 [ff20000000013e30] ksys_write at ffffffff801b6c4a
#6 [ff20000000013e80] __riscv_sys_write at ffffffff801b6cc4
#7 [ff20000000013e90] do_trap_ecall_u at ffffffff80836798
crash>
```
Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
riscv64.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/riscv64.c b/riscv64.c
index 0aaa14b..872be59 100644
--- a/riscv64.c
+++ b/riscv64.c
@@ -747,11 +747,14 @@ riscv64_back_trace_cmd(struct bt_info *bt)
{
struct riscv64_unwind_frame current, previous;
struct stackframe curr_frame;
+ struct riscv64_register * regs;
int level = 0;
if (bt->flags & BT_REGS_NOT_FOUND)
return;
+ regs = (struct riscv64_register *) bt->machdep;
+
current.pc = bt->instptr;
current.sp = bt->stkptr;
current.fp = bt->frameptr;
@@ -788,8 +791,16 @@ riscv64_back_trace_cmd(struct bt_info *bt)
sizeof(curr_frame), "get stack frame", RETURN_ON_ERROR))
return;
- previous.pc = curr_frame.ra;
- previous.fp = curr_frame.fp;
+ /* correct PC and FP of the second frame when the first frame has no callee */
+
+ if (regs && (regs->regs[RISCV64_REGS_EPC] == current.pc) && curr_frame.fp & 0x7){
+ previous.pc = regs->regs[RISCV64_REGS_RA];
+ previous.fp = curr_frame.ra;
+ } else {
+ previous.pc = curr_frame.ra;
+ previous.fp = curr_frame.fp;
+ }
+
previous.sp = current.fp;
riscv64_dump_backtrace_entry(bt, symbol, ¤t, &previous, level++);
--
2.20.1
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
prev parent reply other threads:[~2023-12-04 10:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-04 10:50 [PATCH 1/2] [Crash-utility] RISCV64: Dump NT_PRSTATUS in 'help -n' Song Shuai
2023-12-04 10:50 ` Song Shuai [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231204105015.2341055-2-songshuaishuai@tinylab.org \
--to=songshuaishuai@tinylab.org \
--cc=crash-utility@redhat.com \
--cc=k-hagio-ab@nec.com \
--cc=kexec@lists.infradead.org \
--cc=xianting.tian@linux.alibaba.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).