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@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1435954742-2545-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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

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