diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 31d9d0f04c2b..cc88aec09888 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -87,9 +87,21 @@ static inline void conditional_sti(struct pt_regs *regs) local_irq_enable(); } -static inline void preempt_conditional_sti(struct pt_regs *regs) +static inline void conditional_sti_ist(struct pt_regs *regs) { +#ifdef CONFIG_X86_64 + /* + * X86_64 uses a per CPU stack on the IST for certain traps + * like int3. The task can not be preempted when using one + * of these stacks, thus preemption must be disabled, otherwise + * the stack can be corrupted if the task is scheduled out, + * and another task comes in and uses this stack. + * + * On x86_32 the task keeps its own stack and it is OK if the + * task schedules out. + */ inc_preempt_count(); +#endif if (regs->flags & X86_EFLAGS_IF) local_irq_enable(); } @@ -100,11 +112,13 @@ static inline void conditional_cli(struct pt_regs *regs) local_irq_disable(); } -static inline void preempt_conditional_cli(struct pt_regs *regs) +static inline void conditional_cli_ist(struct pt_regs *regs) { if (regs->flags & X86_EFLAGS_IF) local_irq_disable(); +#ifdef CONFIG_X86_64 dec_preempt_count(); +#endif } static void __kprobes @@ -222,9 +236,9 @@ dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code) if (notify_die(DIE_TRAP, "stack segment", regs, error_code, 12, SIGBUS) == NOTIFY_STOP) return; - preempt_conditional_sti(regs); + conditional_sti_ist(regs); do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL); - preempt_conditional_cli(regs); + conditional_cli_ist(regs); } dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) @@ -316,9 +330,9 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code) return; #endif - preempt_conditional_sti(regs); + conditional_sti_ist(regs); do_trap(3, SIGTRAP, "int3", regs, error_code, NULL); - preempt_conditional_cli(regs); + conditional_cli_ist(regs); } #ifdef CONFIG_X86_64 @@ -412,12 +426,12 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) return; /* It's safe to allow irq's after DR6 has been saved */ - preempt_conditional_sti(regs); + conditional_sti_ist(regs); if (regs->flags & X86_VM_MASK) { handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1); - preempt_conditional_cli(regs); + conditional_cli_ist(regs); return; } @@ -436,7 +450,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) si_code = get_si_code(tsk->thread.debugreg6); if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp) send_sigtrap(tsk, regs, error_code, si_code); - preempt_conditional_cli(regs); + conditional_cli_ist(regs); return; } |