linux-kernel - [PATCH 07/11] x86/retpoline/checksum32: Convert assembler indirect jumps

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Date:   Wed,  3 Jan 2018 15:09:30 -0800
From:   Andi Kleen <andi@...stfloor.org>
To:     tglx@...uxtronix.de
Cc:     torvalds@...ux-foundation.org, gregkh@...ux-foundation.org,
        dwmw@...zon.co.uk, tim.c.chen@...ux.intel.com,
        linux-kernel@...r.kernel.org, dave.hansen@...el.com,
        Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 07/11] x86/retpoline/checksum32: Convert  assembler indirect jumps

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

Convert all indirect jumps in 32bit checksum 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/lib/checksum_32.S | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/checksum_32.S b/arch/x86/lib/checksum_32.S
index 4d34bb548b41..d19862183d4b 100644
--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -29,6 +29,7 @@
 #include <asm/errno.h>
 #include <asm/asm.h>
 #include <asm/export.h>
+#include <asm/jump-asm.h>
 				
 /*
  * computes a partial checksum, e.g. for TCP/UDP fragments
@@ -156,7 +157,7 @@ ENTRY(csum_partial)
 	negl %ebx
 	lea 45f(%ebx,%ebx,2), %ebx
 	testl %esi, %esi
-	jmp *%ebx
+	NOSPEC_JMP %ebx
 
 	# Handle 2-byte-aligned regions
 20:	addw (%esi), %ax
@@ -439,7 +440,7 @@ ENTRY(csum_partial_copy_generic)
 	andl $-32,%edx
 	lea 3f(%ebx,%ebx), %ebx
 	testl %esi, %esi 
-	jmp *%ebx
+	NOSPEC_JMP %ebx
 1:	addl $64,%esi
 	addl $64,%edi 
 	SRC(movb -32(%edx),%bl)	; SRC(movb (%edx),%bl)
-- 
2.14.3