x86/locking: Create stack frame in PV unlock

The assembly PV_UNLOCK function is a callable non-leaf function which
doesn't honor CONFIG_FRAME_POINTER, which can result in bad stack
traces.

Create a stack frame when CONFIG_FRAME_POINTER is enabled.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hpe.com>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/6685a72ddbbd0ad3694337cca0af4b4ea09f5f40.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h
index 9f92c18..9d55f9b 100644 (file)
--- a/arch/x86/include/asm/qspinlock_paravirt.h
+++ b/arch/x86/include/asm/qspinlock_paravirt.h
@@ -36,8 +36,10 @@ PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath);
  */
 asm    (".pushsection .text;"
        ".globl " PV_UNLOCK ";"
+       ".type " PV_UNLOCK ", @function;"
        ".align 4,0x90;"
        PV_UNLOCK ": "
+       FRAME_BEGIN
        "push  %rdx;"
        "mov   $0x1,%eax;"
        "xor   %edx,%edx;"
@@ -45,6 +47,7 @@ asm    (".pushsection .text;"
        "cmp   $0x1,%al;"
        "jne   .slowpath;"
        "pop   %rdx;"
+       FRAME_END
        "ret;"
        ".slowpath: "
        "push   %rsi;"
@@ -52,6 +55,7 @@ asm    (".pushsection .text;"
        "call " PV_UNLOCK_SLOWPATH ";"
        "pop    %rsi;"
        "pop    %rdx;"
+       FRAME_END
        "ret;"
        ".size " PV_UNLOCK ", .-" PV_UNLOCK ";"
        ".popsection");