| Message ID | 1414645978-21968-1-git-send-email-anton@samba.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9caab69..add42d0 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -661,6 +661,13 @@ _GLOBAL(ret_from_except_lite) bl save_nvgprs bl restore_interrupts addi r3,r1,STACK_FRAME_OVERHEAD + /* + * restore_interrupts() is written in c and could clobber all + * volatile registers. We need to reload our thread_info flags + * in r4 for do_notify_resume(). + */ + CURRENT_THREAD_INFO(r9, r1) + ld r4,TI_FLAGS(r9) bl do_notify_resume b ret_from_except
Back in 7230c5644188 ("powerpc: Rework lazy-interrupt handling") we added a call out to restore_interrupts() (written in c) before we call do_notify_resume: bl restore_interrupts addi r3,r1,STACK_FRAME_OVERHEAD bl do_notify_resume Unfortunately do_notify_resume takes two arguments, the second one being the thread_info flags: void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) We do populate r4 earlier, but restore_interrupts() is free to muck it up all it wants. My guess is the gcc compiler gods shone down on us and its register allocator never used r4. Sometimes, rarely, luck is on our side. Signed-off-by: Anton Blanchard <anton@samba.org> Cc: stable@vger.kernel.org --- arch/powerpc/kernel/entry_64.S | 7 +++++++ 1 file changed, 7 insertions(+)