diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/i387.h | 56 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 7 | ||||
| -rw-r--r-- | arch/x86/pci/xen.c | 2 | ||||
| -rw-r--r-- | arch/x86/xen/smp.c | 7 |
4 files changed, 59 insertions, 13 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index 6919e936345b..a29571821b99 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -29,7 +29,7 @@ extern unsigned int sig_xstate_size; extern void fpu_init(void); extern void mxcsr_feature_mask_init(void); extern int init_fpu(struct task_struct *child); -extern asmlinkage void math_state_restore(void); +extern void math_state_restore(void); extern void __math_state_restore(void); extern int dump_fpu(struct pt_regs *, struct user_i387_struct *); @@ -307,9 +307,54 @@ static inline void __clear_fpu(struct task_struct *tsk) } } +/* + * Were we in an interrupt that interrupted kernel mode? + * + * We can do a kernel_fpu_begin/end() pair *ONLY* if that + * pair does nothing at all: TS_USEDFPU must be clear (so + * that we don't try to save the FPU state), and TS must + * be set (so that the clts/stts pair does nothing that is + * visible in the interrupted kernel thread). + */ +static inline bool interrupted_kernel_fpu_idle(void) +{ + return !(current_thread_info()->status & TS_USEDFPU) && + (read_cr0() & X86_CR0_TS); +} + +/* + * Were we in user mode (or vm86 mode) when we were + * interrupted? + * + * Doing kernel_fpu_begin/end() is ok if we are running + * in an interrupt context from user mode - we'll just + * save the FPU state as required. + */ +static inline bool interrupted_user_mode(void) +{ + struct pt_regs *regs = get_irq_regs(); + return regs && user_mode_vm(regs); +} + +/* + * Can we use the FPU in kernel mode with the + * whole "kernel_fpu_begin/end()" sequence? + * + * It's always ok in process context (ie "not interrupt") + * but it is sometimes ok even from an irq. + */ +static inline bool irq_fpu_usable(void) +{ + return !in_interrupt() || + interrupted_user_mode() || + interrupted_kernel_fpu_idle(); +} + static inline void kernel_fpu_begin(void) { struct thread_info *me = current_thread_info(); + + WARN_ON_ONCE(!irq_fpu_usable()); preempt_disable(); if (me->status & TS_USEDFPU) __save_init_fpu(me->task); @@ -323,14 +368,6 @@ static inline void kernel_fpu_end(void) preempt_enable(); } -static inline bool irq_fpu_usable(void) -{ - struct pt_regs *regs; - - return !in_interrupt() || !(regs = get_irq_regs()) || \ - user_mode(regs) || (read_cr0() & X86_CR0_TS); -} - /* * Some instructions like VIA's padlock instructions generate a spurious * DNA fault but don't modify SSE registers. And these instructions @@ -367,6 +404,7 @@ static inline void irq_ts_restore(int TS_state) */ static inline void save_init_fpu(struct task_struct *tsk) { + WARN_ON_ONCE(task_thread_info(tsk)->status & TS_USEDFPU); preempt_disable(); __save_init_fpu(tsk); stts(); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 482ec3af2067..8ba27dbc107a 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -599,10 +599,10 @@ void __math_state_restore(void) * Careful.. There are problems with IBM-designed IRQ13 behaviour. * Don't touch unless you *really* know how it works. * - * Must be called with kernel preemption disabled (in this case, - * local interrupts are disabled at the call-site in entry.S). + * Must be called with kernel preemption disabled (eg with local + * local interrupts as in the case of do_device_not_available). */ -asmlinkage void math_state_restore(void) +void math_state_restore(void) { struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; @@ -631,6 +631,7 @@ EXPORT_SYMBOL_GPL(math_state_restore); dotraplinkage void __kprobes do_device_not_available(struct pt_regs *regs, long error_code) { + WARN_ON_ONCE(!user_mode_vm(regs)); #ifdef CONFIG_MATH_EMULATION if (read_cr0() & X86_CR0_EM) { struct math_emu_info info = { }; diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c index 492ade8c978e..d99346ea8fdb 100644 --- a/arch/x86/pci/xen.c +++ b/arch/x86/pci/xen.c @@ -374,7 +374,7 @@ int __init pci_xen_init(void) int __init pci_xen_hvm_init(void) { - if (!xen_feature(XENFEAT_hvm_pirqs)) + if (!xen_have_vector_callback || !xen_feature(XENFEAT_hvm_pirqs)) return 0; #ifdef CONFIG_ACPI diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index 041d4fe9dfe4..501d4e0244ba 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -409,6 +409,13 @@ static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */ play_dead_common(); HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); cpu_bringup(); + /* + * Balance out the preempt calls - as we are running in cpu_idle + * loop which has been called at bootup from cpu_bringup_and_idle. + * The cpucpu_bringup_and_idle called cpu_bringup which made a + * preempt_disable() So this preempt_enable will balance it out. + */ + preempt_enable(); } #else /* !CONFIG_HOTPLUG_CPU */ |