[PATCH] riscv: Fix ftrace_graph_ret_addr() to use the correct task pointer

[PATCH] riscv: Fix ftrace_graph_ret_addr() to use the correct task pointer

[Rui Qi]

The walk_stackframe() function is used to unwind the stack of a given
task. When function graph tracing is enabled, ftrace_graph_ret_addr()
is called to resolve the original return address if it was modified by
the tracer.

The current code incorrectly passes 'current' instead of 'task' to
ftrace_graph_ret_addr(). This causes incorrect return address resolution
when unwinding a stack of a different task (e.g., when the task is
blocked in __switch_to).

Fix this by passing 'task' instead of 'current' to match the behavior
of other architectures (arm64, loongarch, powerpc, s390, x86).

Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
 arch/riscv/kernel/stacktrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index b41b6255751c..2692d3a06afa 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -87,7 +87,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 		} else {
 			fp = READ_ONCE_TASK_STACK(task, frame->fp);
 			pc = READ_ONCE_TASK_STACK(task, frame->ra);
-			pc = ftrace_graph_ret_addr(current, &graph_idx, pc,
+			pc = ftrace_graph_ret_addr(task, &graph_idx, pc,
 						   &frame->ra);
 			if (pc >= (unsigned long)handle_exception &&
 			    pc < (unsigned long)&ret_from_exception_end) {
-- 
2.20.1

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Re: [PATCH] riscv: Fix ftrace_graph_ret_addr() to use the correct task pointer

[Paul Walmsley]

On Wed, 8 Apr 2026, Rui Qi wrote:

> The walk_stackframe() function is used to unwind the stack of a given
> task. When function graph tracing is enabled, ftrace_graph_ret_addr()
> is called to resolve the original return address if it was modified by
> the tracer.
> 
> The current code incorrectly passes 'current' instead of 'task' to
> ftrace_graph_ret_addr(). This causes incorrect return address resolution
> when unwinding a stack of a different task (e.g., when the task is
> blocked in __switch_to).
> 
> Fix this by passing 'task' instead of 'current' to match the behavior
> of other architectures (arm64, loongarch, powerpc, s390, x86).
> 
> Signed-off-by: Rui Qi <qirui.001@bytedance.com>

Thanks, queued for v7.1-rc.


- Paul

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