x86/process: Consolidate and simplify switch_to_xtra() code

Move the conditional invocation of __switch_to_xtra() into an inline
function so the logic can be shared between 32 and 64 bit.

Remove the handthrough of the TSS pointer and retrieve the pointer directly
in the bitmap handling function. Use this_cpu_ptr() instead of the
per_cpu() indirection.

This is a preparatory change so integration of conditional indirect branch
speculation optimization happens only in one place.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Casey Schaufler <[email protected]>
Cc: Asit Mallick <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Jon Masters <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Dave Stewart <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

1 files changed, 3 insertions, 7 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 5046a3c9dec2..d3e593eb189f 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -59,6 +59,8 @@
 #include <asm/intel_rdt_sched.h>
 #include <asm/proto.h>
 
+#include "process.h"
+
 void __show_regs(struct pt_regs *regs, enum show_regs_mode mode)
 {
 	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
@@ -232,7 +234,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	struct fpu *prev_fpu = &prev->fpu;
 	struct fpu *next_fpu = &next->fpu;
 	int cpu = smp_processor_id();
-	struct tss_struct *tss = &per_cpu(cpu_tss_rw, cpu);
 
 	/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
 
@@ -264,12 +265,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
 		set_iopl_mask(next->iopl);
 
-	/*
-	 * Now maybe handle debug registers and/or IO bitmaps
-	 */
-	if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
-		     task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
-		__switch_to_xtra(prev_p, next_p, tss);
+	switch_to_extra(prev_p, next_p);
 
 	/*
 	 * Leave lazy mode, flushing any hypercalls made here.