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Commit 73cbf687 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
Browse files

x86/asm/entry/32: Open-code LOAD_ARGS32 



This macro is small, has only three callsites, and one of them
is slightly different using a conditional parameter.

A few saved lines aren't worth the resulting obfuscation.

Generated machine code is identical.

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
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/1433271842-9139-2-git-send-email-dvlasenk@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ef0cd5dc

arch/x86/entry/ia32entry.S

+29 −25
Original line number Diff line number Diff line
@@ -29,28 +29,6 @@ 


	.section .entry.text, "ax"



	/*

	 * Reload arg registers from stack in case ptrace changed them.

	 * We don't reload %eax because syscall_trace_enter() returned

	 * the %rax value we should see.  Instead, we just truncate that

	 * value to 32 bits again as we did on entry from user mode.

	 * If it's a new value set by user_regset during entry tracing,

	 * this matches the normal truncation of the user-mode value.

	 * If it's -1 to make us punt the syscall, then (u32)-1 is still

	 * an appropriately invalid value.

	 */

	.macro LOAD_ARGS32 _r9=0

	.if \_r9

	movl R9(%rsp),%r9d

	.endif

	movl RCX(%rsp),%ecx

	movl RDX(%rsp),%edx

	movl RSI(%rsp),%esi

	movl RDI(%rsp),%edi

	movl %eax,%eax			/* zero extension */

	.endm

	



#ifdef CONFIG_PARAVIRT

ENTRY(native_usergs_sysret32)

	swapgs
@@ -269,7 +247,14 @@ sysenter_tracesys: 
	movq	%rax, R8(%rsp)

	movq	%rsp,%rdi        /* &pt_regs -> arg1 */

	call	syscall_trace_enter

	LOAD_ARGS32  /* reload args from stack in case ptrace changed it */



	/* Reload arg registers from stack. (see sysenter_tracesys) */

	movl	RCX(%rsp), %ecx

	movl	RDX(%rsp), %edx

	movl	RSI(%rsp), %esi

	movl	RDI(%rsp), %edi

	movl	%eax, %eax	/* zero extension */



	RESTORE_EXTRA_REGS

	jmp	sysenter_do_call

ENDPROC(ia32_sysenter_target)
@@ -413,7 +398,15 @@ cstar_tracesys: 
	movq	%rax, R8(%rsp)

	movq %rsp,%rdi        /* &pt_regs -> arg1 */

	call syscall_trace_enter

	LOAD_ARGS32 1	/* reload args from stack in case ptrace changed it */

	movl	R9(%rsp),%r9d



	/* Reload arg registers from stack. (see sysenter_tracesys) */

	movl	RCX(%rsp), %ecx

	movl	RDX(%rsp), %edx

	movl	RSI(%rsp), %esi

	movl	RDI(%rsp), %edi

	movl	%eax, %eax	/* zero extension */



	RESTORE_EXTRA_REGS

	xchgl %ebp,%r9d

	jmp cstar_do_call
@@ -502,7 +495,18 @@ ia32_tracesys: 
	SAVE_EXTRA_REGS

	movq %rsp,%rdi        /* &pt_regs -> arg1 */

	call syscall_trace_enter

	LOAD_ARGS32	/* reload args from stack in case ptrace changed it */

	/*

	 * Reload arg registers from stack in case ptrace changed them.

	 * Don't reload %eax because syscall_trace_enter() returned

	 * the %rax value we should see.  But do truncate it to 32 bits.

	 * If it's -1 to make us punt the syscall, then (u32)-1 is still

	 * an appropriately invalid value.

	 */

	movl	RCX(%rsp), %ecx

	movl	RDX(%rsp), %edx

	movl	RSI(%rsp), %esi

	movl	RDI(%rsp), %edi

	movl	%eax, %eax	/* zero extension */

	RESTORE_EXTRA_REGS

	jmp ia32_do_call

END(ia32_syscall)