linux-kernel - [tip:x86/asm] x86/asm/entry/32: Replace RESTORE_RSI

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Message-ID: <tip-c73e36b775a777abd67a1e15481923fcbd2040e1@git.kernel.org>
Date:	Mon, 6 Jul 2015 08:38:25 -0700
From:	tip-bot for Denys Vlasenko <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	oleg@...hat.com, keescook@...omium.org, hpa@...or.com,
	wad@...omium.org, dvlasenk@...hat.com, ast@...mgrid.com,
	bp@...en8.de, tglx@...utronix.de, torvalds@...ux-foundation.org,
	luto@...capital.net, linux-kernel@...r.kernel.org,
	fweisbec@...il.com, rostedt@...dmis.org, peterz@...radead.org,
	mingo@...nel.org
Subject: [tip:x86/asm] x86/asm/entry/32:
  Replace RESTORE_RSI_RDI with open-coded 32-bit reads

Commit-ID:  c73e36b775a777abd67a1e15481923fcbd2040e1
Gitweb:     http://git.kernel.org/tip/c73e36b775a777abd67a1e15481923fcbd2040e1
Author:     Denys Vlasenko <dvlasenk@...hat.com>
AuthorDate: Fri, 3 Jul 2015 22:19:02 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 6 Jul 2015 14:56:50 +0200

x86/asm/entry/32: Replace RESTORE_RSI_RDI with open-coded 32-bit reads

This doesn't change much, but uses shorter 32-bit insns:

        -48 8b 74 24 68         mov    0x68(%rsp),%rsi
        -48 8b 7c 24 70         mov    0x70(%rsp),%rdi
        -48 8b 54 24 60         mov    0x60(%rsp),%rdx
        +8b 54 24 60            mov    0x60(%rsp),%edx
        +8b 74 24 68            mov    0x68(%rsp),%esi
        +8b 7c 24 70            mov    0x70(%rsp),%edi

and does the loads in pt_regs order.

Since these are the only uses of RESTORE_RSI_RDI[_RDX], drop
these macros.

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Drewry <wad@...omium.org>
Link: http://lkml.kernel.org/r/1435954742-2545-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/entry/calling.h         | 6 ------
 arch/x86/entry/entry_64_compat.S | 7 +++++--
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index f4e6308..519207f 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -193,12 +193,6 @@ For 32-bit we have the following conventions - kernel is built with
 	.macro RESTORE_C_REGS_EXCEPT_RCX_R11
 	RESTORE_C_REGS_HELPER 1,0,0,1,1
 	.endm
-	.macro RESTORE_RSI_RDI
-	RESTORE_C_REGS_HELPER 0,0,0,0,0
-	.endm
-	.macro RESTORE_RSI_RDI_RDX
-	RESTORE_C_REGS_HELPER 0,0,0,0,1
-	.endm
 
 	.macro REMOVE_PT_GPREGS_FROM_STACK addskip=0
 	subq $-(15*8+\addskip), %rsp
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index bb187a6..b868cfc 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -140,7 +140,8 @@ sysexit_from_sys_call:
 	 */
 	andl	$~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
 	movl	RIP(%rsp), %ecx		/* User %eip */
-	RESTORE_RSI_RDI
+	movl	RSI(%rsp), %esi
+	movl	RDI(%rsp), %edi
 	xorl	%edx, %edx		/* Do not leak kernel information */
 	xorq	%r8, %r8
 	xorq	%r9, %r9
@@ -366,7 +367,9 @@ cstar_dispatch:
 
 sysretl_from_sys_call:
 	andl	$~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
-	RESTORE_RSI_RDI_RDX
+	movl	RDX(%rsp), %edx
+	movl	RSI(%rsp), %esi
+	movl	RDI(%rsp), %edi
 	movl	RIP(%rsp), %ecx
 	movl	EFLAGS(%rsp), %r11d
 	xorq	%r10, %r10
--
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