linux-kernel - [PATCH v5 08/12] x86/retpoline/checksum32: Convert assembler indirect jumps

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Message-Id: <1515239374-23361-9-git-send-email-dwmw@amazon.co.uk>
Date:   Sat,  6 Jan 2018 11:49:30 +0000
From:   David Woodhouse <dwmw@...zon.co.uk>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Paul Turner <pjt@...gle.com>, LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>, tglx@...utronix.de,
        Kees Cook <keescook@...gle.com>,
        Rik van Riel <riel@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        Jiri Kosina <jikos@...nel.org>, gnomes@...rguk.ukuu.org.uk
Subject: [PATCH v5 08/12] x86/retpoline/checksum32: Convert assembler indirect jumps

Convert all indirect jumps in 32bit checksum assembler code to use
non-speculative sequences when CONFIG_RETPOLINE is enabled.

Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
---
 arch/x86/lib/checksum_32.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/lib/checksum_32.S b/arch/x86/lib/checksum_32.S
index 4d34bb5..98cf15d 100644
--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -29,7 +29,8 @@
 #include <asm/errno.h>
 #include <asm/asm.h>
 #include <asm/export.h>
-				
+#include <asm/nospec-branch.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)
-- 
2.7.4