linux-kernel - [PATCH 3.2 064/104] x86/retpoline/checksum32: Convert assembler indirect jumps

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Date:   Mon, 12 Mar 2018 03:03:34 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Paul Turner" <pjt@...gle.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        gnomes@...rguk.ukuu.org.uk,
        "Tim Chen" <tim.c.chen@...ux.intel.com>,
        "Ingo Molnar" <mingo@...nel.org>,
        "David Woodhouse" <dwmw@...zon.co.uk>,
        "Andi Kleen" <ak@...ux.intel.com>,
        "Rik van Riel" <riel@...hat.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Greg Kroah-Hartman" <gregkh@...ux-foundation.org>,
        "Jiri Kosina" <jikos@...nel.org>,
        "Josh Poimboeuf" <jpoimboe@...hat.com>,
        "Andy Lutomirski" <luto@...capital.net>,
        "Kees Cook" <keescook@...gle.com>,
        "Arjan van de Ven" <arjan@...ux.intel.com>, thomas.lendacky@....com
Subject: [PATCH 3.2 064/104] x86/retpoline/checksum32: Convert assembler
 indirect jumps

3.2.101-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: David Woodhouse <dwmw@...zon.co.uk>

commit 5096732f6f695001fa2d6f1335a2680b37912c69 upstream.

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>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Arjan van de Ven <arjan@...ux.intel.com>
Acked-by: Ingo Molnar <mingo@...nel.org>
Cc: gnomes@...rguk.ukuu.org.uk
Cc: Rik van Riel <riel@...hat.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: thomas.lendacky@....com
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Jiri Kosina <jikos@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Kees Cook <keescook@...gle.com>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...ux-foundation.org>
Cc: Paul Turner <pjt@...gle.com>
Link: https://lkml.kernel.org/r/1515707194-20531-11-git-send-email-dwmw@amazon.co.uk
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/lib/checksum_32.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -28,7 +28,8 @@
 #include <linux/linkage.h>
 #include <asm/dwarf2.h>
 #include <asm/errno.h>
-				
+#include <asm/nospec-branch.h>
+
 /*
  * computes a partial checksum, e.g. for TCP/UDP fragments
  */
@@ -164,7 +165,7 @@ ENTRY(csum_partial)
 	negl %ebx
 	lea 45f(%ebx,%ebx,2), %ebx
 	testl %esi, %esi
-	jmp *%ebx
+	JMP_NOSPEC %ebx
 
 	# Handle 2-byte-aligned regions
 20:	addw (%esi), %ax
@@ -466,7 +467,7 @@ ENTRY(csum_partial_copy_generic)
 	andl $-32,%edx
 	lea 3f(%ebx,%ebx), %ebx
 	testl %esi, %esi 
-	jmp *%ebx
+	JMP_NOSPEC %ebx
 1:	addl $64,%esi
 	addl $64,%edi 
 	SRC(movb -32(%edx),%bl)	; SRC(movb (%edx),%bl)