Commit ff467594 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/asm/entry/64: Save all regs on interrupt entry 



To prepare for the big rewrite of the error and interrupt exit
paths, we will need pt_regs completely filled in.

It's already completely filled in when error_exit runs, so rearrange
interrupt handling to match it.  This will slow down interrupt
handling very slightly (eight instructions), but the
simplification it enables will be more than worth it.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.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: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/d8a766a7f558b30e6e01352854628a2d9943460c.1435952415.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 29ea1b25

arch/x86/entry/calling.h

+0 −3
Original line number Diff line number Diff line
@@ -135,9 +135,6 @@ For 32-bit we have the following conventions - kernel is built with 
	movq %rbp, 4*8+\offset(%rsp)

	movq %rbx, 5*8+\offset(%rsp)

	.endm

	.macro SAVE_EXTRA_REGS_RBP offset=0

	movq %rbp, 4*8+\offset(%rsp)

	.endm



	.macro RESTORE_EXTRA_REGS offset=0

	movq 0*8+\offset(%rsp), %r15

arch/x86/entry/entry_64.S

+9 −20
Original line number Diff line number Diff line
@@ -502,21 +502,13 @@ END(irq_entries_start) 
/* 0(%rsp): ~(interrupt number) */

	.macro interrupt func

	cld

	/*

	 * Since nothing in interrupt handling code touches r12...r15 members

	 * of "struct pt_regs", and since interrupts can nest, we can save

	 * four stack slots and simultaneously provide

	 * an unwind-friendly stack layout by saving "truncated" pt_regs

	 * exactly up to rbp slot, without these members.

	 */

	ALLOC_PT_GPREGS_ON_STACK -RBP

	SAVE_C_REGS -RBP

	/* this goes to 0(%rsp) for unwinder, not for saving the value: */

	SAVE_EXTRA_REGS_RBP -RBP

	ALLOC_PT_GPREGS_ON_STACK

	SAVE_C_REGS

	SAVE_EXTRA_REGS



	leaq	-RBP(%rsp), %rdi		/* arg1 for \func (pointer to pt_regs) */

	movq	%rsp,%rdi	/* arg1 for \func (pointer to pt_regs) */



	testb	$3, CS-RBP(%rsp)

	testb	$3, CS(%rsp)

	jz	1f

	SWAPGS

1:
@@ -553,9 +545,7 @@ ret_from_intr: 
	decl	PER_CPU_VAR(irq_count)



	/* Restore saved previous stack */

	popq	%rsi

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

	leaq	-RBP(%rsi), %rsp

	popq	%rsp



	testb	$3, CS(%rsp)

	jz	retint_kernel
@@ -580,7 +570,7 @@ retint_swapgs: /* return to user-space */ 
	TRACE_IRQS_IRETQ



	SWAPGS

	jmp	restore_c_regs_and_iret

	jmp	restore_regs_and_iret



/* Returning to kernel space */

retint_kernel:
@@ -604,6 +594,8 @@ retint_kernel: 
 * At this label, code paths which return to kernel and to user,

 * which come from interrupts/exception and from syscalls, merge.

 */

restore_regs_and_iret:

	RESTORE_EXTRA_REGS

restore_c_regs_and_iret:

	RESTORE_C_REGS

	REMOVE_PT_GPREGS_FROM_STACK 8
@@ -674,12 +666,10 @@ retint_signal: 
	jz	retint_swapgs

	TRACE_IRQS_ON

	ENABLE_INTERRUPTS(CLBR_NONE)

	SAVE_EXTRA_REGS

	movq	$-1, ORIG_RAX(%rsp)

	xorl	%esi, %esi			/* oldset */

	movq	%rsp, %rdi			/* &pt_regs */

	call	do_notify_resume

	RESTORE_EXTRA_REGS

	DISABLE_INTERRUPTS(CLBR_NONE)

	TRACE_IRQS_OFF

	GET_THREAD_INFO(%rcx)
@@ -1160,7 +1150,6 @@ END(error_entry) 
 */

ENTRY(error_exit)

	movl	%ebx, %eax

	RESTORE_EXTRA_REGS

	DISABLE_INTERRUPTS(CLBR_NONE)

	TRACE_IRQS_OFF

	testl	%eax, %eax

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