Merge branch 'tip/x86/urgent' of... (e24b90b2) · Commits · e / devices / android_kernel_fairphone_FP3

arch/x86/kernel/entry_64.S

+35 −29

Original line number	Diff line number	Diff line
		@@ -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