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Commit ef0cd5dc authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
Browse files

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



This macro is small, has only four 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>
[ Added comments. ]
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/1433271842-9139-1-git-send-email-dvlasenk@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 61b1e3e7

arch/x86/entry/ia32entry.S

+20 −13
Original line number Diff line number Diff line
@@ -29,15 +29,6 @@ 


	.section .entry.text, "ax"



	/* clobbers %rax */

	.macro  CLEAR_RREGS _r9=rax

	xorl 	%eax,%eax

	movq	%rax,R11(%rsp)

	movq	%rax,R10(%rsp)

	movq	%\_r9,R9(%rsp)

	movq	%rax,R8(%rsp)

	.endm



	/*

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

	 * We don't reload %eax because syscall_trace_enter() returned
@@ -243,7 +234,11 @@ sysexit_from_sys_call: 
	TRACE_IRQS_OFF

	testl %edi, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)

	jz \exit

	CLEAR_RREGS

	xorl	%eax, %eax	/* do not leak kernel information */

	movq	%rax, R11(%rsp)

	movq	%rax, R10(%rsp)

	movq	%rax, R9(%rsp)

	movq	%rax, R8(%rsp)

	jmp int_with_check

	.endm
@@ -267,7 +262,11 @@ sysenter_tracesys: 
	jz	sysenter_auditsys

#endif

	SAVE_EXTRA_REGS

	CLEAR_RREGS

	xorl	%eax, %eax	/* do not leak kernel information */

	movq	%rax, R11(%rsp)

	movq	%rax, R10(%rsp)

	movq	%rax, R9(%rsp)

	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 */
@@ -407,7 +406,11 @@ cstar_tracesys: 
#endif

	xchgl %r9d,%ebp

	SAVE_EXTRA_REGS

	CLEAR_RREGS r9

	xorl	%eax, %eax	/* do not leak kernel information */

	movq	%rax, R11(%rsp)

	movq	%rax, R10(%rsp)

	movq	%r9,  R9(%rsp)

	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 */
@@ -422,7 +425,11 @@ ia32_badarg: 
	jmp ia32_sysret



ia32_ret_from_sys_call:

	CLEAR_RREGS

	xorl	%eax, %eax	/* do not leak kernel information */

	movq	%rax, R11(%rsp)

	movq	%rax, R10(%rsp)

	movq	%rax, R9(%rsp)

	movq	%rax, R8(%rsp)

	jmp int_ret_from_sys_call



/*