linux-kernel - [tip:x86/pti] x86/retpoline: Remove the esp/rsp thunk

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Message-ID: <tip-1df37383a8aeabb9b418698f0bcdffea01f4b1b2@git.kernel.org>
Date:   Wed, 24 Jan 2018 03:42:54 -0800
From:   tip-bot for Waiman Long <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, luto@...capital.net, dave.hansen@...el.com,
        dwmw@...zon.co.uk, gregkh@...ux-foundation.org,
        tim.c.chen@...ux.intel.com, jikos@...nel.org,
        arjan@...ux.intel.com, tglx@...utronix.de, law@...hat.com,
        mingo@...nel.org, linux-kernel@...r.kernel.org,
        jpoimboe@...hat.com, hpa@...or.com, keescook@...gle.com,
        thomas.lendacky@....com, ak@...ux.intel.com,
        torvalds@...ux-foundation.org, longman@...hat.com, pjt@...gle.com
Subject: [tip:x86/pti] x86/retpoline: Remove the esp/rsp thunk

Commit-ID:  1df37383a8aeabb9b418698f0bcdffea01f4b1b2
Gitweb:     https://git.kernel.org/tip/1df37383a8aeabb9b418698f0bcdffea01f4b1b2
Author:     Waiman Long <longman@...hat.com>
AuthorDate: Mon, 22 Jan 2018 17:09:34 -0500
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 24 Jan 2018 12:31:55 +0100

x86/retpoline: Remove the esp/rsp thunk

It doesn't make sense to have an indirect call thunk with esp/rsp as
retpoline code won't work correctly with the stack pointer register.
Removing it will help compiler writers to catch error in case such
a thunk call is emitted incorrectly.

Fixes: 76b043848fd2 ("x86/retpoline: Add initial retpoline support")
Suggested-by: Jeff Law <law@...hat.com>
Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: David Woodhouse <dwmw@...zon.co.uk>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Kees Cook <keescook@...gle.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Tim Chen <tim.c.chen@...ux.intel.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: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...ux-foundation.org>
Cc: Paul Turner <pjt@...gle.com>
Link: https://lkml.kernel.org/r/1516658974-27852-1-git-send-email-longman@redhat.com

---
 arch/x86/include/asm/asm-prototypes.h | 1 -
 arch/x86/lib/retpoline.S              | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/x86/include/asm/asm-prototypes.h b/arch/x86/include/asm/asm-prototypes.h
index 0927cdc..1908214 100644
--- a/arch/x86/include/asm/asm-prototypes.h
+++ b/arch/x86/include/asm/asm-prototypes.h
@@ -38,5 +38,4 @@ INDIRECT_THUNK(dx)
 INDIRECT_THUNK(si)
 INDIRECT_THUNK(di)
 INDIRECT_THUNK(bp)
-INDIRECT_THUNK(sp)
 #endif /* CONFIG_RETPOLINE */
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index dfb2ba9..c909961 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -36,7 +36,6 @@ GENERATE_THUNK(_ASM_DX)
 GENERATE_THUNK(_ASM_SI)
 GENERATE_THUNK(_ASM_DI)
 GENERATE_THUNK(_ASM_BP)
-GENERATE_THUNK(_ASM_SP)
 #ifdef CONFIG_64BIT
 GENERATE_THUNK(r8)
 GENERATE_THUNK(r9)