88 lines
2.9 KiB
Diff
88 lines
2.9 KiB
Diff
From 9b69093e623f1d54c373b1e091900d40576c059b Mon Sep 17 00:00:00 2001
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From: Song Shuai <songshuaishuai@tinylab.org>
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Date: Tue, 12 Dec 2023 18:20:51 +0800
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Subject: [PATCH 11/14] RISCV64: Fix 'bt' output when no ra on the stack top
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Same as the Linux commit f766f77a74f5 ("riscv/stacktrace: Fix
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stack output without ra on the stack top").
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When a function doesn't have a callee, then it will not
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push ra into the stack, such as lkdtm functions, so
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correct the FP of the second frame and use pt_regs to get
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the right PC of the second frame.
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Before this patch, the `bt -f` outputs only the first frame with
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the wrong PC and FP of next frame:
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```
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crash> bt -f
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PID: 1 TASK: ff600000000e0000 CPU: 1 COMMAND: "sh"
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#0 [ff20000000013cf0] lkdtm_EXCEPTION at ffffffff805303c0
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[PC: ffffffff805303c0 RA: ff20000000013d10 SP: ff20000000013cf0 SIZE: 16] <- wrong next PC
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ff20000000013cf0: 0000000000000001 ff20000000013d10 <- next FP
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ff20000000013d00: ff20000000013d40
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crash>
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```
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After this patch, the `bt` outputs the full frames:
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```
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crash> bt
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PID: 1 TASK: ff600000000e0000 CPU: 1 COMMAND: "sh"
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#0 [ff20000000013cf0] lkdtm_EXCEPTION at ffffffff805303c0
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#1 [ff20000000013d00] lkdtm_do_action at ffffffff8052fe36
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#2 [ff20000000013d10] direct_entry at ffffffff80530018
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#3 [ff20000000013d40] full_proxy_write at ffffffff80305044
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#4 [ff20000000013d80] vfs_write at ffffffff801b68b4
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#5 [ff20000000013e30] ksys_write at ffffffff801b6c4a
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#6 [ff20000000013e80] __riscv_sys_write at ffffffff801b6cc4
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#7 [ff20000000013e90] do_trap_ecall_u at ffffffff80836798
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crash>
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```
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Acked-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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riscv64.c | 15 +++++++++++++--
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1 file changed, 13 insertions(+), 2 deletions(-)
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diff --git a/riscv64.c b/riscv64.c
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index 0aaa14b2671e..872be594d72b 100644
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--- a/riscv64.c
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+++ b/riscv64.c
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@@ -747,11 +747,14 @@ riscv64_back_trace_cmd(struct bt_info *bt)
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{
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struct riscv64_unwind_frame current, previous;
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struct stackframe curr_frame;
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+ struct riscv64_register * regs;
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int level = 0;
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if (bt->flags & BT_REGS_NOT_FOUND)
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return;
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+ regs = (struct riscv64_register *) bt->machdep;
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+
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current.pc = bt->instptr;
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current.sp = bt->stkptr;
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current.fp = bt->frameptr;
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@@ -788,8 +791,16 @@ riscv64_back_trace_cmd(struct bt_info *bt)
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sizeof(curr_frame), "get stack frame", RETURN_ON_ERROR))
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return;
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- previous.pc = curr_frame.ra;
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- previous.fp = curr_frame.fp;
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+ /* correct PC and FP of the second frame when the first frame has no callee */
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+
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+ if (regs && (regs->regs[RISCV64_REGS_EPC] == current.pc) && curr_frame.fp & 0x7){
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+ previous.pc = regs->regs[RISCV64_REGS_RA];
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+ previous.fp = curr_frame.ra;
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+ } else {
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+ previous.pc = curr_frame.ra;
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+ previous.fp = curr_frame.fp;
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+ }
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+
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previous.sp = current.fp;
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riscv64_dump_backtrace_entry(bt, symbol, ¤t, &previous, level++);
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--
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2.41.0
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