| Message ID | 1416947722-14712-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index fb5ba6d..088dca5 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -660,7 +660,13 @@ _GLOBAL(ret_from_except_lite) b .ret_from_except_lite 2: bl .save_nvgprs + /* + * Use a non volatile GPR to save and restore our thread_info flags + * across the call to restore_interrupts. + */ + mr r30,r4 bl .restore_interrupts + mr r4,r30 addi r3,r1,STACK_FRAME_OVERHEAD bl .do_notify_resume b .ret_from_except
This is a note to let you know that I have just added a patch titled powerpc: do_notify_resume can be called with bad thread_info flags argument to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 38c96f03e228598aea71749ddb77efefb6f5998a Mon Sep 17 00:00:00 2001 From: Anton Blanchard <anton@samba.org> Date: Fri, 31 Oct 2014 16:50:57 +1100 Subject: powerpc: do_notify_resume can be called with bad thread_info flags argument commit 808be31426af57af22268ef0fcb42617beb3d15b upstream. Back in 7230c5644188 ("powerpc: Rework lazy-interrupt handling") we added a call out to restore_interrupts() (written in c) before calling 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 (the second argument) 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. LLVM on the other hand did trample r4. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> [ kamal: backport to 3.13-stable: context ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/powerpc/kernel/entry_64.S | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.9.1