linux-kernel - [PATCH v2 04/12] x86/retpoline/ftrace: Convert ftrace assembler indirect jumps

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Date:   Wed,  3 Jan 2018 18:00:11 -0800
From:   Andi Kleen <andi@...stfloor.org>
To:     tglx@...utronix.de
Cc:     torvalds@...ux-foundation.org, gregkh@...ux-foundation.org,
        linux-kernel@...r.kernel.org, tim.c.chen@...ux.intel.com,
        Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH v2 04/12] x86/retpoline/ftrace: Convert ftrace assembler indirect jumps

From: Andi Kleen <ak@...ux.intel.com>

Convert all indirect jumps in ftrace assembler code to use
non speculative sequences.

Based on code from David Woodhouse and Tim Chen

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/kernel/ftrace_32.S | 3 ++-
 arch/x86/kernel/ftrace_64.S | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index b6c6468e10bc..c0c10ba53375 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -8,6 +8,7 @@
 #include <asm/segment.h>
 #include <asm/export.h>
 #include <asm/ftrace.h>
+#include <asm/jump-asm.h>
 
 #ifdef CC_USING_FENTRY
 # define function_hook	__fentry__
@@ -241,5 +242,5 @@ return_to_handler:
 	movl	%eax, %ecx
 	popl	%edx
 	popl	%eax
-	jmp	*%ecx
+	NOSPEC_JMP	%ecx
 #endif
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index c832291d948a..4814c4b30b8d 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -7,7 +7,7 @@
 #include <asm/ptrace.h>
 #include <asm/ftrace.h>
 #include <asm/export.h>
-
+#include <asm/jump-asm.h>
 
 	.code64
 	.section .entry.text, "ax"
@@ -286,7 +286,7 @@ trace:
 	 * ip and parent ip are used and the list function is called when
 	 * function tracing is enabled.
 	 */
-	call   *ftrace_trace_function
+	NOSPEC_CALL ftrace_trace_function
 
 	restore_mcount_regs
 
@@ -329,5 +329,5 @@ GLOBAL(return_to_handler)
 	movq 8(%rsp), %rdx
 	movq (%rsp), %rax
 	addq $24, %rsp
-	jmp *%rdi
+	NOSPEC_JMP %rdi
 #endif
-- 
2.14.3