linux-kernel - [PATCH 3.16 27/76] x86/retpoline/ftrace: Convert ftrace assembler indirect jumps

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Message-ID: <lsq.1520823972.814802306@decadent.org.uk>
Date:   Mon, 12 Mar 2018 03:06:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Andy Lutomirski" <luto@...capital.net>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Josh Poimboeuf" <jpoimboe@...hat.com>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>, gnomes@...rguk.ukuu.org.uk,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Kees Cook" <keescook@...gle.com>,
        "Jiri Kosina" <jikos@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...ux-foundation.org>,
        "David Woodhouse" <dwmw@...zon.co.uk>, thomas.lendacky@....com,
        "Arjan van de Ven" <arjan@...ux.intel.com>,
        "Rik van Riel" <riel@...hat.com>,
        "Andi Kleen" <ak@...ux.intel.com>, "Paul Turner" <pjt@...gle.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Tim Chen" <tim.c.chen@...ux.intel.com>
Subject: [PATCH 3.16 27/76] x86/retpoline/ftrace: Convert ftrace assembler
 indirect jumps

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

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

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

commit 9351803bd803cdbeb9b5a7850b7b6f464806e3db upstream.

Convert all indirect jumps in ftrace 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/1515707194-20531-8-git-send-email-dwmw@amazon.co.uk
[bwh: Backported to 3.16: adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1189,7 +1189,8 @@ trace:
 	movl 0x4(%ebp), %edx
 	subl $MCOUNT_INSN_SIZE, %eax
 
-	call *ftrace_trace_function
+	movl ftrace_trace_function, %ecx
+	CALL_NOSPEC %ecx
 
 	popl %edx
 	popl %ecx
@@ -1224,7 +1225,7 @@ return_to_handler:
 	movl %eax, %ecx
 	popl %edx
 	popl %eax
-	jmp *%ecx
+	JMP_NOSPEC %ecx
 #endif
 
 #ifdef CONFIG_TRACING
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -7,7 +7,7 @@
 #include <linux/linkage.h>
 #include <asm/ptrace.h>
 #include <asm/ftrace.h>
-
+#include <asm/nospec-branch.h>
 
 	.code64
 	.section .entry.text, "ax"
@@ -210,8 +210,8 @@ trace:
 #endif
 	subq $MCOUNT_INSN_SIZE, %rdi
 
-	call   *ftrace_trace_function
-
+	movq ftrace_trace_function, %r8
+	CALL_NOSPEC %r8
 	MCOUNT_RESTORE_FRAME
 
 	jmp ftrace_stub
@@ -254,5 +254,5 @@ GLOBAL(return_to_handler)
 	movq 8(%rsp), %rdx
 	movq (%rsp), %rax
 	addq $24, %rsp
-	jmp *%rdi
+	JMP_NOSPEC %rdi
 #endif