x86/asm/xen: Create stack frames in xen-asm.S

xen_irq_enable_direct(), xen_restore_fl_direct(), and check_events() are
callable non-leaf functions which don't honor CONFIG_FRAME_POINTER,
which can result in bad stack traces.

Create stack frames for them when CONFIG_FRAME_POINTER is enabled.

Signed-off-by: Josh Poimboeuf <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Bernd Petrovitsch <[e-mail]>
Cc: Boris Ostrovsky <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: Chris J Arges <[e-mail]>
Cc: David Vrabel <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Jiri Slaby <[e-mail]>
Cc: Konrad Rzeszutek Wilk <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Michal Marek <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Pedro Alves <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/xen/xen-asm.S

···
 #include <asm/asm-offsets.h>
 #include <asm/percpu.h>
 #include <asm/processor-flags.h>
+#include <asm/frame.h>
 
 #include "xen-asm.h"
 
···
  * then enter the hypervisor to get them handled.
  */
 ENTRY(xen_irq_enable_direct)
+	FRAME_BEGIN
 	/* Unmask events */
 	movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
 
···
 2:	call check_events
 1:
 ENDPATCH(xen_irq_enable_direct)
+	FRAME_END
 	ret
 	ENDPROC(xen_irq_enable_direct)
 	RELOC(xen_irq_enable_direct, 2b+1)
···
  * enters the hypervisor to get them delivered if so.
  */
 ENTRY(xen_restore_fl_direct)
+	FRAME_BEGIN
 #ifdef CONFIG_X86_64
 	testw $X86_EFLAGS_IF, %di
 #else
···
 2:	call check_events
 1:
 ENDPATCH(xen_restore_fl_direct)
+	FRAME_END
 	ret
 	ENDPROC(xen_restore_fl_direct)
 	RELOC(xen_restore_fl_direct, 2b+1)
···
  * Force an event check by making a hypercall, but preserve regs
  * before making the call.
  */
-check_events:
+ENTRY(check_events)
+	FRAME_BEGIN
 #ifdef CONFIG_X86_32
 	push %eax
 	push %ecx
···
 	pop %rcx
 	pop %rax
 #endif
+	FRAME_END
 	ret
+ENDPROC(check_events)