[tip:x86/debug] x86/xen: Add stack frame dependency to hypercall inline asm calls

[tip-bot for Josh Poimboeuf]

Commit-ID:  0e8e2238b52e5301d1d1d4a298ec5b72ac54c702
Gitweb:     http://git.kernel.org/tip/0e8e2238b52e5301d1d1d4a298ec5b72ac54c702
Author:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Thu, 21 Jan 2016 16:49:09 -0600
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 24 Feb 2016 08:35:41 +0100

x86/xen: Add stack frame dependency to hypercall inline asm calls

If a hypercall is inlined at the beginning of a function, gcc can insert
the call instruction before setting up a stack frame, which breaks frame
pointer convention if CONFIG_FRAME_POINTER is enabled and can result in
a bad stack trace.

Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by
listing the stack pointer as an output operand for the hypercall inline
asm statements.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Bernd Petrovitsch <bernd@xxxxxxxxxxxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Chris J Arges <chris.j.arges@xxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxx>
Cc: Pedro Alves <palves@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: live-patching@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/c6face5a46713108bded9c4c103637222abc4528.1453405861.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/xen/hypercall.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index 3bcdcc8..a12a047 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -110,9 +110,10 @@ extern struct { char _entry[32]; } hypercall_page[];
 	register unsigned long __arg2 asm(__HYPERCALL_ARG2REG) = __arg2; \
 	register unsigned long __arg3 asm(__HYPERCALL_ARG3REG) = __arg3; \
 	register unsigned long __arg4 asm(__HYPERCALL_ARG4REG) = __arg4; \
-	register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5;
+	register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5; \
+	register void *__sp asm(_ASM_SP);
 
-#define __HYPERCALL_0PARAM	"=r" (__res)
+#define __HYPERCALL_0PARAM	"=r" (__res), "+r" (__sp)
 #define __HYPERCALL_1PARAM	__HYPERCALL_0PARAM, "+r" (__arg1)
 #define __HYPERCALL_2PARAM	__HYPERCALL_1PARAM, "+r" (__arg2)
 #define __HYPERCALL_3PARAM	__HYPERCALL_2PARAM, "+r" (__arg3)