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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: Andy 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-11-02 00:58:59 -07:00 committed by Ingo Molnar
parent 9da78ba6b4
commit 26c4ef9c49
3 changed files with 27 additions and 11 deletions
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34
arch/x86/entry/entry_64.S
View File

@ -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:
/*

2
arch/x86/entry/entry_64_compat.S
View File

@ -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)

2
arch/x86/kernel/head_64.S
View File

@ -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