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x86,64: Simplify save_regs()

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The save_regs function that saves the regs on low level
irq entry is complicated because of the fact it changes
its stack in the middle and also because it manipulates
data allocated in the caller frame and accesses there
are directly calculated from callee rsp value with the
return address in the middle of the way.

This complicates the static stack offsets calculation and
require more dynamic ones. It also needs a save/restore
of the function's return address.

To simplify and optimize this, turn save_regs() into a
macro.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
This commit is contained in:
Frederic Weisbecker 2011-07-01 01:51:22 +02:00
parent 47ce11a2b6
commit 1871853f7a
1 changed files with 16 additions and 26 deletions
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42
arch/x86/kernel/entry_64.S
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@ -297,27 +297,22 @@ ENDPROC(native_usergs_sysret64)
.endm
/* save partial stack frame */
.pushsection .kprobes.text, "ax"
ENTRY(save_args)
XCPT_FRAME
.macro SAVE_ARGS_IRQ
cld
/*
* start from rbp in pt_regs and jump over
* return address.
*/
movq_cfi rdi, RDI+8-RBP
movq_cfi rsi, RSI+8-RBP
movq_cfi rdx, RDX+8-RBP
movq_cfi rcx, RCX+8-RBP
movq_cfi rax, RAX+8-RBP
movq_cfi r8, R8+8-RBP
movq_cfi r9, R9+8-RBP
movq_cfi r10, R10+8-RBP
movq_cfi r11, R11+8-RBP
/* start from rbp in pt_regs and jump over */
movq_cfi rdi, RDI-RBP
movq_cfi rsi, RSI-RBP
movq_cfi rdx, RDX-RBP
movq_cfi rcx, RCX-RBP
movq_cfi rax, RAX-RBP
movq_cfi r8, R8-RBP
movq_cfi r9, R9-RBP
movq_cfi r10, R10-RBP
movq_cfi r11, R11-RBP
leaq -RBP+8(%rsp),%rdi /* arg1 for handler */
movq_cfi rbp, 8 /* push %rbp */
leaq 8(%rsp), %rbp /* mov %rsp, %ebp */
leaq -RBP(%rsp),%rdi /* arg1 for handler */
movq_cfi rbp, 0 /* push %rbp */
movq %rsp, %rbp
testl $3, CS(%rdi)
je 1f
SWAPGS
@ -329,19 +324,14 @@ ENTRY(save_args)
*/
1: incl PER_CPU_VAR(irq_count)
jne 2f
popq_cfi %rax /* move return address... */
mov PER_CPU_VAR(irq_stack_ptr),%rsp
EMPTY_FRAME 0
pushq_cfi %rbp /* backlink for unwinder */
pushq_cfi %rax /* ... to the new stack */
/*
* We entered an interrupt context - irqs are off:
*/
2: TRACE_IRQS_OFF
ret
CFI_ENDPROC
END(save_args)
.popsection
.endm
ENTRY(save_rest)
PARTIAL_FRAME 1 REST_SKIP+8
@ -791,7 +781,7 @@ END(interrupt)
/* reserve pt_regs for scratch regs and rbp */
subq $ORIG_RAX-RBP, %rsp
CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP
call save_args
SAVE_ARGS_IRQ
PARTIAL_FRAME 0
call \func
.endm