[PATCH 4.14 047/159] x86/entry/64: Pass SP0 directly to load_sp0()

Greg Kroah-Hartman
2017-12-22T09:00:43Z

From: Andy Lutomirski <luto@kernel.org>

commit da51da189a24bb9b7e2d5a123be096e51a4695a5 upstream.

load_sp0() had an odd signature:

void load_sp0(struct tss_struct *tss, struct thread_struct *thread);

Simplify it to:

void load_sp0(unsigned long sp0);

Also simplify a few get_cpu()/put_cpu() sequences to
preempt_disable()/preempt_enable().

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/2655d8b42ed940aa384fe18ee1129bbbcf730a08.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/paravirt.h | 5 ++---
arch/x86/include/asm/paravirt_types.h | 2 +-
arch/x86/include/asm/processor.h | 9 ++++-----
arch/x86/kernel/cpu/common.c | 4 ++--
arch/x86/kernel/process_32.c | 2 +-
arch/x86/kernel/process_64.c | 2 +-
arch/x86/kernel/vm86_32.c | 14 ++++++--------
arch/x86/xen/enlighten_pv.c | 7 +++----
8 files changed, 20 insertions(+), 25 deletions(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -16,10 +16,9 @@
#include <linux/cpumask.h>
#include <asm/frame.h>

-static inline void load_sp0(struct tss_struct *tss,
- struct thread_struct *thread)
+static inline void load_sp0(unsigned long sp0)
{
- PVOP_VCALL2(pv_cpu_ops.load_sp0, tss, thread);
+ PVOP_VCALL1(pv_cpu_ops.load_sp0, sp0);
}

/* The paravirtualized CPUID instruction. */
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -134,7 +134,7 @@ struct pv_cpu_ops {
void (*alloc_ldt)(struct desc_struct *ldt, unsigned entries);
void (*free_ldt)(struct desc_struct *ldt, unsigned entries);

- void (*load_sp0)(struct tss_struct *tss, struct thread_struct *t);
+ void (*load_sp0)(unsigned long sp0);

void (*set_iopl_mask)(unsigned mask);

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -518,9 +518,9 @@ static inline void native_set_iopl_mask(
}

static inline void
-native_load_sp0(struct tss_struct *tss, struct thread_struct *thread)
+native_load_sp0(unsigned long sp0)
{
- tss->x86_tss.sp0 = thread->sp0;
+ this_cpu_write(cpu_tss.x86_tss.sp0, sp0);
}

static inline void native_swapgs(void)
@@ -545,10 +545,9 @@ static inline unsigned long current_top_
#else
#define __cpuid native_cpuid

-static inline void load_sp0(struct tss_struct *tss,
- struct thread_struct *thread)
+static inline void load_sp0(unsigned long sp0)
{
- native_load_sp0(tss, thread);
+ native_load_sp0(sp0);
}

#define set_iopl_mask native_set_iopl_mask
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1570,7 +1570,7 @@ void cpu_init(void)
initialize_tlbstate_and_flush();
enter_lazy_tlb(&init_mm, me);

- load_sp0(t, &current->thread);
+ load_sp0(current->thread.sp0);
set_tss_desc(cpu, t);
load_TR_desc();
load_mm_ldt(&init_mm);
@@ -1625,7 +1625,7 @@ void cpu_init(void)
initialize_tlbstate_and_flush();
enter_lazy_tlb(&init_mm, curr);

- load_sp0(t, thread);
+ load_sp0(thread->sp0);
set_tss_desc(cpu, t);
load_TR_desc();
load_mm_ldt(&init_mm);
--- 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,
* current_thread_info(). Refresh the SYSENTER configuration in
* case prev or next is vm86.
*/
- load_sp0(tss, next);
+ load_sp0(next->sp0);
refresh_sysenter_cs(next);
this_cpu_write(cpu_current_top_of_stack,
(unsigned long)task_stack_page(next_p) +
--- 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,
this_cpu_write(current_task, next_p);

/* Reload sp0. */
- load_sp0(tss, next);
+ load_sp0(next->sp0);

/*
* Now maybe reload the debug registers and handle I/O bitmaps
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -95,7 +95,6 @@

void save_v86_state(struct kernel_vm86_regs *regs, int retval)
{
- struct tss_struct *tss;
struct task_struct *tsk = current;
struct vm86plus_struct __user *user;
struct vm86 *vm86 = current->thread.vm86;
@@ -147,13 +146,13 @@ void save_v86_state(struct kernel_vm86_r
do_exit(SIGSEGV);
}

- tss = &per_cpu(cpu_tss, get_cpu());
+ preempt_disable();
tsk->thread.sp0 = vm86->saved_sp0;
tsk->thread.sysenter_cs = __KERNEL_CS;
- load_sp0(tss, &tsk->thread);
+ load_sp0(tsk->thread.sp0);
refresh_sysenter_cs(&tsk->thread);
vm86->saved_sp0 = 0;
- put_cpu();
+ preempt_enable();

memcpy(&regs->pt, &vm86->regs32, sizeof(struct pt_regs));

@@ -239,7 +238,6 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd

static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
{
- struct tss_struct *tss;
struct task_struct *tsk = current;
struct vm86 *vm86 = tsk->thread.vm86;
struct kernel_vm86_regs vm86regs;
@@ -367,8 +365,8 @@ static long do_sys_vm86(struct vm86plus_
vm86->saved_sp0 = tsk->thread.sp0;
lazy_save_gs(vm86->regs32.gs);

- tss = &per_cpu(cpu_tss, get_cpu());
/* make room for real-mode segments */
+ preempt_disable();
tsk->thread.sp0 += 16;

if (static_cpu_has(X86_FEATURE_SEP)) {
@@ -376,8 +374,8 @@ static long do_sys_vm86(struct vm86plus_
refresh_sysenter_cs(&tsk->thread);
}

- load_sp0(tss, &tsk->thread);
- put_cpu();
+ load_sp0(tsk->thread.sp0);
+ preempt_enable();

if (vm86->flags & VM86_SCREEN_BITMAP)
mark_screen_rdonly(tsk->mm);
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -811,15 +811,14 @@ static void __init xen_write_gdt_entry_b
}
}

-static void xen_load_sp0(struct tss_struct *tss,
- struct thread_struct *thread)
+static void xen_load_sp0(unsigned long sp0)
{
struct multicall_space mcs;

mcs = xen_mc_entry(0);
- MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0);
+ MULTI_stack_switch(mcs.mc, __KERNEL_DS, sp0);
xen_mc_issue(PARAVIRT_LAZY_CPU);
- tss->x86_tss.sp0 = thread->sp0;
+ this_cpu_write(cpu_tss.x86_tss.sp0, sp0);
}

void xen_set_iopl_mask(unsigned mask)