diff options
Diffstat (limited to 'arch/x86/kernel/entry_64.S')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 52 |
1 files changed, 28 insertions, 24 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1333d98..e0eca00 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1530,6 +1530,7 @@ 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 @@ -1554,6 +1555,7 @@ ENTRY(nmi) */ lea 6*8(%rsp), %rdx test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi + CFI_REMEMBER_STATE nested_nmi: /* @@ -1585,10 +1587,12 @@ 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 @@ -1624,6 +1628,10 @@ first_nmi: * NMI may zero out. 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 it */ + movq (%rsp), %rdx + CFI_RESTORE rdx + /* Set the NMI executing variable on the stack. */ pushq_cfi $1 @@ -1631,14 +1639,31 @@ first_nmi: .rept 5 pushq_cfi 6*8(%rsp) .endr + CFI_DEF_CFA_OFFSET SS+8-RIP + + /* + * 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 @@ -1646,7 +1671,6 @@ first_nmi: * caused by an exception and nested NMI will start here, and * can still be preempted by 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 @@ -1675,26 +1699,6 @@ 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 |
