x86/entry/64: Remove all remaining direct thread_struct::sp0 reads

commit 46f5a10a721ce8dce8cc8fe55279b49e1c6b3288 upstream.

The only remaining readers in context switch code or vm86(), and
they all just want to update TSS.sp0 to match the current task.
Replace them all with a new helper update_sp0().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
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/2d231687f4ff288c9d9e98d7861b7df374246ac3.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 0fe929d1ff70a44344c1af81e003bcd97e4c53b1..92dca86a39e3a78b83de42fed3c24a54a6e6534a 100644 (file)
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -85,4 +85,10 @@ static inline void refresh_sysenter_cs(struct thread_struct *thread)
 }
 #endif
 
+/* This is used when switching tasks or entering/exiting vm86 mode. */
+static inline void update_sp0(struct task_struct *task)
+{
+       load_sp0(task->thread.sp0);
+}
+
 #endif /* _ASM_X86_SWITCH_TO_H */

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 40b85870e42932ebe37d96b925eca7b337a7c0bd..45bf0c5f93e15103060d67d5245756ab72ce8fe5 100644 (file)
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -287,7 +287,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         * current_thread_info().  Refresh the SYSENTER configuration in
         * case prev or next is vm86.
         */
-       load_sp0(next->sp0);
+       update_sp0(next_p);
        refresh_sysenter_cs(next);
        this_cpu_write(cpu_current_top_of_stack,
                       (unsigned long)task_stack_page(next_p) +

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 2124304fb77abc16aaf2609fab1c9b81957c8fcc..45e3809583926c90b2db758d9cc4486ea5a8c4b5 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -465,7 +465,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
        this_cpu_write(current_task, next_p);
 
        /* Reload sp0. */
-       load_sp0(next->sp0);
+       update_sp0(next_p);
 
        /*
         * Now maybe reload the debug registers and handle I/O bitmaps

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index f75e305a9b63af0979b5cd975c92814eed77a5d5..5edb27f1a2c407ff8173161fb87cbd9130b76e8e 100644 (file)
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -149,7 +149,7 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
        preempt_disable();
        tsk->thread.sp0 = vm86->saved_sp0;
        tsk->thread.sysenter_cs = __KERNEL_CS;
-       load_sp0(tsk->thread.sp0);
+       update_sp0(tsk);
        refresh_sysenter_cs(&tsk->thread);
        vm86->saved_sp0 = 0;
        preempt_enable();
@@ -374,7 +374,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
                refresh_sysenter_cs(&tsk->thread);
        }
 
-       load_sp0(tsk->thread.sp0);
+       update_sp0(tsk);
        preempt_enable();
 
        if (vm86->flags & VM86_SCREEN_BITMAP)