diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2023-09-22 02:24:41 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-09-22 13:29:27 +0300 |
| commit | c5cc3ca707bc916a3f326364751a41f25040aef3 (patch) | |
| tree | 5dbeda1745c02940d6bd715c4e8723426ddd50b8 /arch/powerpc | |
| parent | c3f4309693758b13fbb34b3741c2e2801ad28769 (diff) | |
| download | linux-c5cc3ca707bc916a3f326364751a41f25040aef3.tar.xz | |
powerpc/stacktrace: Fix arch_stack_walk_reliable()
The changes to copy_thread() made in commit eed7c420aac7 ("powerpc:
copy_thread differentiate kthreads and user mode threads") inadvertently
broke arch_stack_walk_reliable() because it has knowledge of the stack
layout.
Fix it by changing the condition to match the new logic in
copy_thread(). The changes make the comments about the stack layout
incorrect, rather than rephrasing them just refer the reader to
copy_thread().
Also the comment about the stack backchain is no longer true, since
commit edbd0387f324 ("powerpc: copy_thread add a back chain to the
switch stack frame"), so remove that as well.
Fixes: eed7c420aac7 ("powerpc: copy_thread differentiate kthreads and user mode threads")
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230921232441.1181843-1-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/stacktrace.c | 27 |
1 files changed, 5 insertions, 22 deletions
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c index b15f15dcacb5..e6a958a5da27 100644 --- a/arch/powerpc/kernel/stacktrace.c +++ b/arch/powerpc/kernel/stacktrace.c @@ -73,29 +73,12 @@ int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consum bool firstframe; stack_end = stack_page + THREAD_SIZE; - if (!is_idle_task(task)) { - /* - * For user tasks, this is the SP value loaded on - * kernel entry, see "PACAKSAVE(r13)" in _switch() and - * system_call_common(). - * - * Likewise for non-swapper kernel threads, - * this also happens to be the top of the stack - * as setup by copy_thread(). - * - * Note that stack backlinks are not properly setup by - * copy_thread() and thus, a forked task() will have - * an unreliable stack trace until it's been - * _switch()'ed to for the first time. - */ - stack_end -= STACK_USER_INT_FRAME_SIZE; - } else { - /* - * idle tasks have a custom stack layout, - * c.f. cpu_idle_thread_init(). - */ + + // See copy_thread() for details. + if (task->flags & PF_KTHREAD) stack_end -= STACK_FRAME_MIN_SIZE; - } + else + stack_end -= STACK_USER_INT_FRAME_SIZE; if (task == current) sp = current_stack_frame(); |