[06/39] x86/entry/32: Split off return-to-kernel path

Commit Message

Joerg Roedel July 11, 2018, 11:29 a.m. UTC

From: Joerg Roedel <[e-mail]>

Use a separate return path when we know we are returning to
the kernel. This allows us to put the PTI cr3-switch and the
switch to the entry-stack into the return-to-user path
without further checking.

Signed-off-by: Joerg Roedel <[e-mail]>
---
 arch/x86/entry/entry_32.S | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Patch

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 571209e..61303fa 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -65,7 +65,7 @@ 
 # define preempt_stop(clobbers)	DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
 #else
 # define preempt_stop(clobbers)
-# define resume_kernel		restore_all
+# define resume_kernel		restore_all_kernel
 #endif
 
 .macro TRACE_IRQS_IRET
@@ -399,9 +399,9 @@  ENTRY(resume_kernel)
 	DISABLE_INTERRUPTS(CLBR_ANY)
 .Lneed_resched:
 	cmpl	$0, PER_CPU_VAR(__preempt_count)
-	jnz	restore_all
+	jnz	restore_all_kernel
 	testl	$X86_EFLAGS_IF, PT_EFLAGS(%esp)	# interrupts off (exception path) ?
-	jz	restore_all
+	jz	restore_all_kernel
 	call	preempt_schedule_irq
 	jmp	.Lneed_resched
 END(resume_kernel)
@@ -606,6 +606,11 @@  restore_all:
 	 */
 	INTERRUPT_RETURN
 
+restore_all_kernel:
+	TRACE_IRQS_IRET
+	RESTORE_REGS 4
+	jmp	.Lirq_return
+
 .section .fixup, "ax"
 ENTRY(iret_exc	)
 	pushl	$0				# no error code