From c30eb760e3ecc7aebf37e557baecefb244733caa Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 2 Nov 2017 00:59:14 -0700 Subject: [PATCH] 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 Reviewed-by: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/2d231687f4ff288c9d9e98d7861b7df374246ac3.1509609304.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/switch_to.h | 6 ++++++ arch/x86/kernel/process_32.c | 2 +- arch/x86/kernel/process_64.c | 2 +- arch/x86/kernel/vm86_32.c | 4 ++-- 4 files changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h index 0fe929d1ff70..92dca86a39e3 100644 --- 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 40b85870e429..45bf0c5f93e1 100644 --- 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 2124304fb77a..45e380958392 100644 --- 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 f75e305a9b63..5edb27f1a2c4 100644 --- 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) -- 2.20.1