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Commit 911d2bb5 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
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x86/asm/entry/64: Use more readable constants 



Constants such as SS+8 or SS+8-RIP are mysterious.
In most cases, SS+8 is just meant to be SIZEOF_PTREGS,
SS+8-RIP is RIP's offset in the iret frame.

This patch changes some of these constants to be less
mysterious.

No code changes (verified with objdump).

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1d20491384773bd606e23a382fac23ddb49b5178.1424989793.git.luto@amacapital.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 14f6e953

arch/x86/include/asm/calling.h

+2 −0
Original line number Diff line number Diff line
@@ -88,6 +88,8 @@ For 32-bit we have the following conventions - kernel is built with 
#define RSP		19*8

#define SS		20*8



#define SIZEOF_PTREGS	21*8



	.macro ALLOC_PT_GPREGS_ON_STACK addskip=0

	subq	$15*8+\addskip, %rsp

	CFI_ADJUST_CFA_OFFSET 15*8+\addskip

arch/x86/kernel/entry_64.S

+16 −12
Original line number Diff line number Diff line
@@ -164,12 +164,12 @@ ENDPROC(native_usergs_sysret64) 
 * initial frame state for interrupts (and exceptions without error code)

 */

	.macro INTR_FRAME start=1 offset=0

	EMPTY_FRAME \start, SS+8+\offset-RIP

	/*CFI_REL_OFFSET ss, SS+\offset-RIP*/

	CFI_REL_OFFSET rsp, RSP+\offset-RIP

	/*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/

	/*CFI_REL_OFFSET cs, CS+\offset-RIP*/

	CFI_REL_OFFSET rip, RIP+\offset-RIP

	EMPTY_FRAME \start, 5*8+\offset

	/*CFI_REL_OFFSET ss, 4*8+\offset*/

	CFI_REL_OFFSET rsp, 3*8+\offset

	/*CFI_REL_OFFSET rflags, 2*8+\offset*/

	/*CFI_REL_OFFSET cs, 1*8+\offset*/

	CFI_REL_OFFSET rip, 0*8+\offset

	.endm



/*
@@ -177,7 +177,7 @@ ENDPROC(native_usergs_sysret64) 
 * with vector already pushed)

 */

	.macro XCPT_FRAME start=1 offset=0

	INTR_FRAME \start, RIP+\offset-ORIG_RAX

	INTR_FRAME \start, 1*8+\offset

	.endm



/*
@@ -645,10 +645,14 @@ END(interrupt) 
	cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp

	CFI_DEF_CFA_REGISTER	rsi

	pushq %rsi

	/*

	 * For debugger:

	 * "CFA (Current Frame Address) is the value on stack + offset"

	 */

	CFI_ESCAPE	0x0f /* DW_CFA_def_cfa_expression */, 6, \

			0x77 /* DW_OP_breg7 */, 0, \

			0x77 /* DW_OP_breg7 (rsp) */, 0, \

			0x06 /* DW_OP_deref */, \

			0x08 /* DW_OP_const1u */, SS+8-RBP, \

			0x08 /* DW_OP_const1u */, SIZEOF_PTREGS-RBP, \

			0x22 /* DW_OP_plus */

	/* We entered an interrupt context - irqs are off: */

	TRACE_IRQS_OFF
@@ -674,7 +678,7 @@ ret_from_intr: 


	/* Restore saved previous stack */

	popq %rsi

	CFI_DEF_CFA rsi,SS+8-RBP	/* reg/off reset after def_cfa_expr */

	CFI_DEF_CFA rsi,SIZEOF_PTREGS-RBP /* reg/off reset after def_cfa_expr */

	/* return code expects complete pt_regs - adjust rsp accordingly: */

	leaq -RBP(%rsi),%rsp

	CFI_DEF_CFA_REGISTER	rsp
@@ -1549,7 +1553,7 @@ first_nmi: 
	.rept 5

	pushq_cfi 11*8(%rsp)

	.endr

	CFI_DEF_CFA_OFFSET SS+8-RIP

	CFI_DEF_CFA_OFFSET 5*8



	/* Everything up to here is safe from nested NMIs */
@@ -1577,7 +1581,7 @@ repeat_nmi: 
	pushq_cfi -6*8(%rsp)

	.endr

	subq $(5*8), %rsp

	CFI_DEF_CFA_OFFSET SS+8-RIP

	CFI_DEF_CFA_OFFSET 5*8

end_repeat_nmi:



	/*