From 51356ce60e5915a6bd812873186ed54e45c2699d Mon Sep 17 00:00:00 2001 From: Clément Léger Date: Mon, 9 Dec 2024 16:57:12 +0100 Subject: riscv: stacktrace: fix backtracing through exceptions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Prior to commit 5d5fc33ce58e ("riscv: Improve exception and system call latency"), backtrace through exception worked since ra was filled with ret_from_exception symbol address and the stacktrace code checked 'pc' to be equal to that symbol. Now that handle_exception uses regular 'call' instructions, this isn't working anymore and backtrace stops at handle_exception(). Since there are multiple call site to C code in the exception handling path, rather than checking multiple potential return addresses, add a new symbol at the end of exception handling and check pc to be in that range. Fixes: 5d5fc33ce58e ("riscv: Improve exception and system call latency") Signed-off-by: Clément Léger Tested-by: Alexandre Ghiti Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20241209155714.1239665-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/stacktrace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/riscv/kernel/stacktrace.c') diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index 153a2db4c5fa..d4355c770c36 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -17,6 +17,7 @@ #ifdef CONFIG_FRAME_POINTER extern asmlinkage void handle_exception(void); +extern unsigned long ret_from_exception_end; static inline int fp_is_valid(unsigned long fp, unsigned long sp) { @@ -71,7 +72,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, fp = frame->fp; pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra, &frame->ra); - if (pc == (unsigned long)handle_exception) { + if (pc >= (unsigned long)handle_exception && + pc < (unsigned long)&ret_from_exception_end) { if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc))) break; -- cgit v1.2.3