Commit e24b90b2 authored by Ingo Molnar's avatar Ingo Molnar

Merge branch 'tip/x86/urgent' of...

Merge branch 'tip/x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into x86/asm
parents 458ce291 79fb4ad6
......@@ -1529,6 +1529,7 @@ ENTRY(nmi)
/* Use %rdx as out temp variable throughout */
pushq_cfi %rdx
CFI_REL_OFFSET rdx, 0
/*
* If %cs was not the kernel segment, then the NMI triggered in user
......@@ -1553,6 +1554,7 @@ ENTRY(nmi)
*/
lea 6*8(%rsp), %rdx
test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
CFI_REMEMBER_STATE
nested_nmi:
/*
......@@ -1584,10 +1586,12 @@ nested_nmi:
nested_nmi_out:
popq_cfi %rdx
CFI_RESTORE rdx
/* No need to check faults here */
INTERRUPT_RETURN
CFI_RESTORE_STATE
first_nmi:
/*
* Because nested NMIs will use the pushed location that we
......@@ -1619,10 +1623,15 @@ first_nmi:
* | pt_regs |
* +-------------------------+
*
* The saved RIP is used to fix up the copied RIP that a nested
* NMI may zero out. The original stack frame and the temp storage
* The saved stack frame is used to fix up the copied stack frame
* that a nested NMI may change to make the interrupted NMI iret jump
* to the repeat_nmi. The original stack frame and the temp storage
* is also used by nested NMIs and can not be trusted on exit.
*/
/* Do not pop rdx, nested NMIs will corrupt that part of the stack */
movq (%rsp), %rdx
CFI_RESTORE rdx
/* Set the NMI executing variable on the stack. */
pushq_cfi $1
......@@ -1630,22 +1639,39 @@ first_nmi:
.rept 5
pushq_cfi 6*8(%rsp)
.endr
CFI_DEF_CFA_OFFSET SS+8-RIP
/* Everything up to here is safe from nested NMIs */
/*
* If there was a nested NMI, the first NMI's iret will return
* here. But NMIs are still enabled and we can take another
* nested NMI. The nested NMI checks the interrupted RIP to see
* if it is between repeat_nmi and end_repeat_nmi, and if so
* it will just return, as we are about to repeat an NMI anyway.
* This makes it safe to copy to the stack frame that a nested
* NMI will update.
*/
repeat_nmi:
/*
* Update the stack variable to say we are still in NMI (the update
* is benign for the non-repeat case, where 1 was pushed just above
* to this very stack slot).
*/
movq $1, 5*8(%rsp)
/* Make another copy, this one may be modified by nested NMIs */
.rept 5
pushq_cfi 4*8(%rsp)
.endr
/* Do not pop rdx, nested NMIs will corrupt it */
movq 11*8(%rsp), %rdx
CFI_DEF_CFA_OFFSET SS+8-RIP
end_repeat_nmi:
/*
* Everything below this point can be preempted by a nested
* NMI if the first NMI took an exception. Repeated NMIs
* caused by an exception and nested NMI will start here, and
* can still be preempted by another NMI.
* NMI if the first NMI took an exception and reset our iret stack
* so that we repeat another NMI.
*/
restart_nmi:
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
subq $ORIG_RAX-R15, %rsp
CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
......@@ -1674,26 +1700,6 @@ nmi_restore:
CFI_ENDPROC
END(nmi)
/*
* If an NMI hit an iret because of an exception or breakpoint,
* it can lose its NMI context, and a nested NMI may come in.
* In that case, the nested NMI will change the preempted NMI's
* stack to jump to here when it does the final iret.
*/
repeat_nmi:
INTR_FRAME
/* Update the stack variable to say we are still in NMI */
movq $1, 5*8(%rsp)
/* copy the saved stack back to copy stack */
.rept 5
pushq_cfi 4*8(%rsp)
.endr
jmp restart_nmi
CFI_ENDPROC
end_repeat_nmi:
ENTRY(ignore_sysret)
CFI_STARTPROC
mov $-ENOSYS,%eax
......
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