diff options
Diffstat (limited to 'include/asm-x86/i387.h')
| -rw-r--r-- | include/asm-x86/i387.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h index 96fa8449ff11..6d3b21063419 100644 --- a/include/asm-x86/i387.h +++ b/include/asm-x86/i387.h @@ -13,6 +13,7 @@ #include <linux/sched.h> #include <linux/kernel_stat.h> #include <linux/regset.h> +#include <linux/hardirq.h> #include <asm/asm.h> #include <asm/processor.h> #include <asm/sigcontext.h> @@ -236,6 +237,37 @@ static inline void kernel_fpu_end(void) preempt_enable(); } +/* + * Some instructions like VIA's padlock instructions generate a spurious + * DNA fault but don't modify SSE registers. And these instructions + * get used from interrupt context aswell. To prevent these kernel instructions + * in interrupt context interact wrongly with other user/kernel fpu usage, we + * should use them only in the context of irq_ts_save/restore() + */ +static inline int irq_ts_save(void) +{ + /* + * If we are in process context, we are ok to take a spurious DNA fault. + * Otherwise, doing clts() in process context require pre-emption to + * be disabled or some heavy lifting like kernel_fpu_begin() + */ + if (!in_interrupt()) + return 0; + + if (read_cr0() & X86_CR0_TS) { + clts(); + return 1; + } + + return 0; +} + +static inline void irq_ts_restore(int TS_state) +{ + if (TS_state) + stts(); +} + #ifdef CONFIG_X86_64 static inline void save_init_fpu(struct task_struct *tsk) |