[Crash-utility] [PATCH 5/6] LoongArch64: avoid replacing a valid RA with stack noise

The fallback prologue scanner may find a saved RA slot and read a word from the stack. In corrupted, interrupted, or partially unwound frames, that word is not guaranteed to be a kernel return address. Do not blindly replace the current RA with the scanned stack value. Keep the existing RA unless the scanned value is a kernel address, or unless the current RA is already not a kernel address. This keeps the fallback scanner from discarding a better caller candidate with obvious stack noise. Signed-off-by: Ming Wang <wangming01(a)loongson.cn&gt; --- loongarch64.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/loongarch64.c b/loongarch64.c index c25a3bbf6d6c..34e29c9f2d67 100644 --- a/loongarch64.c +++ b/loongarch64.c @@ -702,11 +702,17 @@ loongarch64_analyze_function(ulong start, ulong offset, previous->sp = current->sp + spadjust; - if (rapos && !readmem(rapos, KVADDR, &current->ra, - sizeof(current->ra), "RA from stack", - RETURN_ON_ERROR)) { - error(FATAL, "Cannot read RA from stack %lx", rapos); - return; + if (rapos) { + ulong ra; + + if (!readmem(rapos, KVADDR, &ra, sizeof(ra), "RA from stack", + RETURN_ON_ERROR)) { + error(FATAL, "Cannot read RA from stack %lx", rapos); + return; + } + + if (IS_KVADDR(ra) || !IS_KVADDR(current->ra)) + current->ra = ra; } } -- 2.43.0