[tip:x86/debug] x86/paravirt: Add stack frame dependency to PVOP inline asm calls - =?UTF-8?B?dGlwLWJvdCBmb3IgSm9zaCBQb2ltYm9ldWYgPHRpcGJvdEB6eXRvci5jb20+?=

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Cc: jpoimboe@redhat.com, mmarek@suse.cz, chrisw@sous-sol.org,
	rusty@rustcorp.com.au, dvlasenk@redhat.com, bp@alien8.de,
	brgerst@gmail.com, luto@amacapital.net, jeremy@goop.org,
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	luto@kernel.org, hpa@zytor.com, jslaby@suse.cz,
	bernd@petrovitsch.priv.at, torvalds@linux-foundation.org,
	tglx@linutronix.de, palves@redhat.com, peterz@infradead.org,
	akataria@vmware.com, mingo@kernel.org,
	chris.j.arges@canonical.com, acme@kernel.org,
	akpm@linux-foundation.org, bp@suse.de
Subject: [tip:x86/debug] x86/paravirt: Add stack frame dependency to PVOP inline asm calls
Date: Tue, 23 Feb 2016 00:56:52 -0800	[thread overview]
Message-ID: <tip-48b86d5c38a817ddf718d3ea5369cd2e885f28f3@git.kernel.org> (raw)
In-Reply-To: <6a13e48c5a8cf2de1aa112ae2d4c0ac194096282.1453405861.git.jpoimboe@redhat.com>

Commit-ID:  48b86d5c38a817ddf718d3ea5369cd2e885f28f3
Gitweb:     http://git.kernel.org/tip/48b86d5c38a817ddf718d3ea5369cd2e885f28f3
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Thu, 21 Jan 2016 16:49:12 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 23 Feb 2016 09:03:55 +0100

x86/paravirt: Add stack frame dependency to PVOP inline asm calls

If a PVOP call macro 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 PVOP inline asm
statements.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alok Kataria <akataria@vmware.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: Chris Wright <chrisw@sous-sol.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
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: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/6a13e48c5a8cf2de1aa112ae2d4c0ac194096282.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/paravirt_types.h | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 77db561..e8c2326 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -466,8 +466,9 @@ int paravirt_disable_iospace(void);
  * makes sure the incoming and outgoing types are always correct.
  */
 #ifdef CONFIG_X86_32
-#define PVOP_VCALL_ARGS				\
-	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx
+#define PVOP_VCALL_ARGS							\
+	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx;	\
+	register void *__sp asm("esp")
 #define PVOP_CALL_ARGS			PVOP_VCALL_ARGS
 
 #define PVOP_CALL_ARG1(x)		"a" ((unsigned long)(x))
@@ -485,9 +486,10 @@ int paravirt_disable_iospace(void);
 #define VEXTRA_CLOBBERS
 #else  /* CONFIG_X86_64 */
 /* [re]ax isn't an arg, but the return val */
-#define PVOP_VCALL_ARGS					\
-	unsigned long __edi = __edi, __esi = __esi,	\
-		__edx = __edx, __ecx = __ecx, __eax = __eax
+#define PVOP_VCALL_ARGS						\
+	unsigned long __edi = __edi, __esi = __esi,		\
+		__edx = __edx, __ecx = __ecx, __eax = __eax;	\
+	register void *__sp asm("rsp")
 #define PVOP_CALL_ARGS		PVOP_VCALL_ARGS
 
 #define PVOP_CALL_ARG1(x)		"D" ((unsigned long)(x))
@@ -526,7 +528,7 @@ int paravirt_disable_iospace(void);
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : call_clbr			\
+				     : call_clbr, "+r" (__sp)		\
 				     : paravirt_type(op),		\
 				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
@@ -536,7 +538,7 @@ int paravirt_disable_iospace(void);
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : call_clbr			\
+				     : call_clbr, "+r" (__sp)		\
 				     : paravirt_type(op),		\
 				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
@@ -563,7 +565,7 @@ int paravirt_disable_iospace(void);
 		asm volatile(pre					\
 			     paravirt_alt(PARAVIRT_CALL)		\
 			     post					\
-			     : call_clbr				\
+			     : call_clbr, "+r" (__sp)			\
 			     : paravirt_type(op),			\
 			       paravirt_clobber(clbr),			\
 			       ##__VA_ARGS__				\
