When a function doesn't have a callee, then it will not push ra
into the stack, such as lkdtm_BUG() function:
addi sp,sp,-16
sd s0,8(sp)
addi s0,sp,16
ebreak
The struct stackframe use {fp,ra} to get information from
stack, if walk_stackframe() with pr_regs, we will obtain
wrong value and bad stacktrace,
[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
---[ end trace 18da3fbdf08e25d5 ]---
Correct the next fp and pc, after that, full stacktrace
shown as expects,
[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
[<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c
[<ffffffe00066c372>] direct_entry+0xc0/0x10a
[<ffffffe000439f86>] full_proxy_write+0x42/0x6a
[<ffffffe000309626>] vfs_write+0x7e/0x214
[<ffffffe00030992a>] ksys_write+0x98/0xc0
[<ffffffe000309960>] sys_write+0xe/0x16
[<ffffffe0002014bc>] ret_from_syscall+0x0/0x2
---[ end trace 61917f3d9a9fadcd ]---
Signed-off-by: Chen Huang <[email protected]>
Signed-off-by: Kefeng Wang <[email protected]>
---
arch/riscv/kernel/stacktrace.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 595342910c3f..3842fac26e85 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -57,9 +57,14 @@ void notrace walk_stackframe(struct task_struct *task,
struct pt_regs *regs,
/* Unwind stack frame */
frame = (struct stackframe *)fp - 1;
sp = fp;
- fp = frame->fp;
- pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
- (unsigned long *)(fp - 8));
+ if (regs && (pc == regs->epc) && (frame->fp & 0x7)) {
+ fp = frame->ra;
+ pc = regs->ra;
+ } else {
+ fp = frame->fp;
+ pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
+ (unsigned long *)(fp - 8));
+ }
}
}
--
2.17.1
