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Commit 26c4ef9c authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/entry/64: Split the IRET-to-user and IRET-to-kernel paths 



These code paths will diverge soon.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/dccf8c7b3750199b4b30383c812d4e2931811509.1509609304.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9da78ba6

arch/x86/entry/entry_64.S

+25 −9
Original line number Diff line number Diff line
@@ -321,7 +321,7 @@ syscall_return_via_sysret: 


opportunistic_sysret_failed:

	SWAPGS

	jmp	restore_regs_and_iret

	jmp	restore_regs_and_return_to_usermode

END(entry_SYSCALL_64)



ENTRY(stub_ptregs_64)
@@ -423,7 +423,7 @@ ENTRY(ret_from_fork) 
	call	syscall_return_slowpath	/* returns with IRQs disabled */

	TRACE_IRQS_ON			/* user mode is traced as IRQS on */

	SWAPGS

	jmp	restore_regs_and_iret

	jmp	restore_regs_and_return_to_usermode



1:

	/* kernel thread */
@@ -612,7 +612,20 @@ GLOBAL(retint_user) 
	call	prepare_exit_to_usermode

	TRACE_IRQS_IRETQ

	SWAPGS

	jmp	restore_regs_and_iret



GLOBAL(restore_regs_and_return_to_usermode)

#ifdef CONFIG_DEBUG_ENTRY

	/* Assert that pt_regs indicates user mode. */

	testl	$3, CS(%rsp)

	jnz	1f

	ud2

1:

#endif

	RESTORE_EXTRA_REGS

	RESTORE_C_REGS

	REMOVE_PT_GPREGS_FROM_STACK 8

	INTERRUPT_RETURN





/* Returning to kernel space */

retint_kernel:
@@ -632,11 +645,14 @@ retint_kernel: 
	 */

	TRACE_IRQS_IRETQ



/*

 * At this label, code paths which return to kernel and to user,

 * which come from interrupts/exception and from syscalls, merge.

 */

GLOBAL(restore_regs_and_iret)

GLOBAL(restore_regs_and_return_to_kernel)

#ifdef CONFIG_DEBUG_ENTRY

	/* Assert that pt_regs indicates kernel mode. */

	testl	$3, CS(%rsp)

	jz	1f

	ud2

1:

#endif

	RESTORE_EXTRA_REGS

	RESTORE_C_REGS

	REMOVE_PT_GPREGS_FROM_STACK 8
@@ -1327,7 +1343,7 @@ ENTRY(nmi) 
	 * work, because we don't want to enable interrupts.

	 */

	SWAPGS

	jmp	restore_regs_and_iret

	jmp	restore_regs_and_return_to_usermode



.Lnmi_from_kernel:

	/*

arch/x86/entry/entry_64_compat.S

+1 −1
Original line number Diff line number Diff line
@@ -337,7 +337,7 @@ ENTRY(entry_INT80_compat) 
	/* Go back to user mode. */

	TRACE_IRQS_ON

	SWAPGS

	jmp	restore_regs_and_iret

	jmp	restore_regs_and_return_to_usermode

END(entry_INT80_compat)



ENTRY(stub32_clone)

arch/x86/kernel/head_64.S

+1 −1
Original line number Diff line number Diff line
@@ -326,7 +326,7 @@ early_idt_handler_common: 


20:

	decl early_recursion_flag(%rip)

	jmp restore_regs_and_iret

	jmp restore_regs_and_return_to_kernel

END(early_idt_handler_common)



	__INITDATA