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x86/asm/entry/64: Use more readable constants

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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: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andy 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Denys Vlasenko 2015-02-26 14:40:36 -08:00 committed by Ingo Molnar
parent 14f6e9532d
commit 911d2bb5cc
2 changed files with 18 additions and 12 deletions
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2
arch/x86/include/asm/calling.h
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@ -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

28
arch/x86/kernel/entry_64.S
View File

@ -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:
/*