Commit 90a6acc4 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Ingo Molnar
Browse files

x86/entry/64: Move the switch_to_thread_stack() call to interrupt_entry() 



We can also move the CLD, SWAPGS, and the switch_to_thread_stack() call
to the interrupt_entry() helper function. As we do not want call depths
of two, convert switch_to_thread_stack() to a macro.

However, switch_to_thread_stack() has another user in entry_64_compat.S,
which currently expects it to be a function. To keep the code changes
in this patch minimal, create a wrapper function.

The switch to a macro means that there is some binary code duplication
if CONFIG_IA32_EMULATION=y is enabled. Therefore, the size reduction
differs whether CONFIG_IA32_EMULATION is enabled or not:

CONFIG_IA32_EMULATION=y (-0.13k):
   text	   data	    bss	    dec	    hex	filename
  17158	      0	      0	  17158	   4306	entry_64.o-orig
  17028	      0	      0	  17028	   4284	entry_64.o

CONFIG_IA32_EMULATION=n (-0.27k):
   text	   data	    bss	    dec	    hex	filename
  17158	      0	      0	  17158	   4306	entry_64.o-orig
  16882	      0	      0	  16882	   41f2	entry_64.o

Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180220210113.6725-4-linux@dominikbrodowski.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2ba64741

arch/x86/entry/entry_64.S

+37 −29
Original line number Diff line number Diff line
@@ -537,6 +537,31 @@ END(irq_entries_start) 
	decl	PER_CPU_VAR(irq_count)

.endm



/*

 * Switch to the thread stack.  This is called with the IRET frame and

 * orig_ax on the stack.  (That is, RDI..R12 are not on the stack and

 * space has not been allocated for them.)

 */

.macro DO_SWITCH_TO_THREAD_STACK

	pushq	%rdi

	/* Need to switch before accessing the thread stack. */

	SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi

	movq	%rsp, %rdi

	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp

	UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI



	pushq	7*8(%rdi)		/* regs->ss */

	pushq	6*8(%rdi)		/* regs->rsp */

	pushq	5*8(%rdi)		/* regs->eflags */

	pushq	4*8(%rdi)		/* regs->cs */

	pushq	3*8(%rdi)		/* regs->ip */

	pushq	2*8(%rdi)		/* regs->orig_ax */

	pushq	8(%rdi)			/* return address */

	UNWIND_HINT_FUNC



	movq	(%rdi), %rdi

.endm



/*

 * Interrupt entry/exit.

 *
@@ -544,8 +569,16 @@ END(irq_entries_start) 
 *

 * Entry runs with interrupts off.

 */

/* 8(%rsp): ~(interrupt number) */

ENTRY(interrupt_entry)

	UNWIND_HINT_FUNC

	cld



	testb	$3, CS-ORIG_RAX+8(%rsp)

	jz	1f

	SWAPGS

	DO_SWITCH_TO_THREAD_STACK

1:



	PUSH_AND_CLEAR_REGS save_ret=1

	ENCODE_FRAME_POINTER 8
@@ -577,14 +610,6 @@ END(interrupt_entry) 


/* 0(%rsp): ~(interrupt number) */

	.macro interrupt func

	cld



	testb	$3, CS-ORIG_RAX(%rsp)

	jz	1f

	SWAPGS

	call	switch_to_thread_stack

1:



	call	interrupt_entry



	UNWIND_HINT_REGS indirect=1
@@ -858,33 +883,16 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt 
 */

#define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + ((x) - 1) * 8)



/*

 * Switch to the thread stack.  This is called with the IRET frame and

 * orig_ax on the stack.  (That is, RDI..R12 are not on the stack and

 * space has not been allocated for them.)

 */

#if defined(CONFIG_IA32_EMULATION)

/* entry_64_compat.S::entry_INT80_compat expects this to be an ASM function */

ENTRY(switch_to_thread_stack)

	UNWIND_HINT_FUNC



	pushq	%rdi

	/* Need to switch before accessing the thread stack. */

	SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi

	movq	%rsp, %rdi

	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp

	UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI



	pushq	7*8(%rdi)		/* regs->ss */

	pushq	6*8(%rdi)		/* regs->rsp */

	pushq	5*8(%rdi)		/* regs->eflags */

	pushq	4*8(%rdi)		/* regs->cs */

	pushq	3*8(%rdi)		/* regs->ip */

	pushq	2*8(%rdi)		/* regs->orig_ax */

	pushq	8(%rdi)			/* return address */

	UNWIND_HINT_FUNC

	DO_SWITCH_TO_THREAD_STACK



	movq	(%rdi), %rdi

	ret

END(switch_to_thread_stack)

#endif



.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1

ENTRY(\sym)

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