[tip:x86/asm] x86/asm/entry/32: Replace RESTORE_RSI_RDI with open-coded 32-bit reads
From: tip-bot for Denys Vlasenko
Date: Mon Jul 06 2015 - 11:39:43 EST
Commit-ID: c73e36b775a777abd67a1e15481923fcbd2040e1
Gitweb: http://git.kernel.org/tip/c73e36b775a777abd67a1e15481923fcbd2040e1
Author: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
AuthorDate: Fri, 3 Jul 2015 22:19:02 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Drewry <wad@xxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1435954742-2545-1-git-send-email-dvlasenk@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/