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x86/entry/64: Open-code switch_to_thread_stack()

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Open-code the two instances which called switch_to_thread_stack(). This
allows us to remove the wrapper around DO_SWITCH_TO_THREAD_STACK.

While at it, update the UNWIND hint to reflect where the IRET frame is,
and update the commentary to reflect what we are actually doing here.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Thomas 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/20180220210113.6725-7-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dominik Brodowski 2018-02-20 22:01:13 +01:00 committed by Ingo Molnar
parent b2855d8d2d
commit f3d415ea46
2 changed files with 55 additions and 38 deletions
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76
arch/x86/entry/entry_64.S
View File

@ -538,17 +538,48 @@ END(irq_entries_start)
.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.)
* Interrupt entry helper function.
*
* Entry runs with interrupts off. Stack layout at entry:
* +----------------------------------------------------+
* | regs->ss |
* | regs->rsp |
* | regs->eflags |
* | regs->cs |
* | regs->ip |
* +----------------------------------------------------+
* | regs->orig_ax = ~(interrupt number) |
* +----------------------------------------------------+
* | return address |
* +----------------------------------------------------+
*/
.macro DO_SWITCH_TO_THREAD_STACK
ENTRY(interrupt_entry)
UNWIND_HINT_FUNC
ASM_CLAC
cld
testb $3, CS-ORIG_RAX+8(%rsp)
jz 1f
SWAPGS
/*
* Switch to the thread stack. The IRET frame and orig_ax are
* on the stack, as well as the return address. RDI..R12 are
* not (yet) on the stack and space has not (yet) been
* allocated for them.
*/
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
/*
* We have RDI, return address, and orig_ax on the stack on
* top of the IRET frame. That means offset=24
*/
UNWIND_HINT_IRET_REGS base=%rdi offset=24
pushq 7*8(%rdi) /* regs->ss */
pushq 6*8(%rdi) /* regs->rsp */
@ -560,25 +591,6 @@ END(irq_entries_start)
UNWIND_HINT_FUNC
movq (%rdi), %rdi
.endm
/*
* Interrupt entry/exit.
*
* Interrupt entry points save only callee clobbered registers in fast path.
*
* Entry runs with interrupts off.
*/
/* 8(%rsp): ~(interrupt number) */
ENTRY(interrupt_entry)
UNWIND_HINT_FUNC
ASM_CLAC
cld
testb $3, CS-ORIG_RAX+8(%rsp)
jz 1f
SWAPGS
DO_SWITCH_TO_THREAD_STACK
1:
PUSH_AND_CLEAR_REGS save_ret=1
@ -592,7 +604,7 @@ ENTRY(interrupt_entry)
*
* We need to tell lockdep that IRQs are off. We can't do this until
* we fix gsbase, and we should do it before enter_from_user_mode
* (which can take locks). Since TRACE_IRQS_OFF idempotent,
* (which can take locks). Since TRACE_IRQS_OFF is idempotent,
* the simplest way to handle it is to just call it twice if
* we enter from user mode. There's no reason to optimize this since
* TRACE_IRQS_OFF is a no-op if lockdep is off.
@ -609,6 +621,9 @@ ENTRY(interrupt_entry)
ret
END(interrupt_entry)
/* Interrupt entry/exit. */
/*
* The interrupt stubs push (~vector+0x80) onto the stack and
* then jump to common_interrupt.
@ -878,17 +893,6 @@ 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)
#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
DO_SWITCH_TO_THREAD_STACK
ret
END(switch_to_thread_stack)
#endif
.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
ENTRY(\sym)
UNWIND_HINT_IRET_REGS offset=\has_error_code*8

17
arch/x86/entry/entry_64_compat.S
View File

@ -347,10 +347,23 @@ ENTRY(entry_INT80_compat)
*/
movl %eax, %eax
/* switch to thread stack expects orig_ax and rdi to be pushed */
pushq %rax /* pt_regs->orig_ax */
pushq %rdi /* pt_regs->di */
/* switch to thread stack expects orig_ax to be pushed */
call switch_to_thread_stack
/* 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
pushq 6*8(%rdi) /* regs->ss */
pushq 5*8(%rdi) /* regs->rsp */
pushq 4*8(%rdi) /* regs->eflags */
pushq 3*8(%rdi) /* regs->cs */
pushq 2*8(%rdi) /* regs->ip */
pushq 1*8(%rdi) /* regs->orig_ax */
movq (%rdi), %rdi /* restore %rdi */
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */