diff options
Diffstat (limited to 'arch/x86/kernel/process_32.c')
| -rw-r--r-- | arch/x86/kernel/process_32.c | 43 |
1 files changed, 39 insertions, 4 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 91e147b486d..a3790a3f8a8 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -36,6 +36,7 @@ #include <linux/personality.h> #include <linux/tick.h> #include <linux/percpu.h> +#include <linux/prctl.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -523,11 +524,11 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) } EXPORT_SYMBOL_GPL(start_thread); -#ifdef CONFIG_SECCOMP static void hard_disable_TSC(void) { write_cr4(read_cr4() | X86_CR4_TSD); } + void disable_TSC(void) { preempt_disable(); @@ -539,11 +540,47 @@ void disable_TSC(void) hard_disable_TSC(); preempt_enable(); } + static void hard_enable_TSC(void) { write_cr4(read_cr4() & ~X86_CR4_TSD); } -#endif /* CONFIG_SECCOMP */ + +void enable_TSC(void) +{ + preempt_disable(); + if (test_and_clear_thread_flag(TIF_NOTSC)) + /* + * Must flip the CPU state synchronously with + * TIF_NOTSC in the current running context. + */ + hard_enable_TSC(); + preempt_enable(); +} + +int get_tsc_mode(unsigned long adr) +{ + unsigned int val; + + if (test_thread_flag(TIF_NOTSC)) + val = PR_TSC_SIGSEGV; + else + val = PR_TSC_ENABLE; + + return put_user(val, (unsigned int __user *)adr); +} + +int set_tsc_mode(unsigned int val) +{ + if (val == PR_TSC_SIGSEGV) + disable_TSC(); + else if (val == PR_TSC_ENABLE) + enable_TSC(); + else + return -EINVAL; + + return 0; +} static noinline void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, @@ -577,7 +614,6 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, set_debugreg(next->debugreg7, 7); } -#ifdef CONFIG_SECCOMP if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ test_tsk_thread_flag(next_p, TIF_NOTSC)) { /* prev and next are different */ @@ -586,7 +622,6 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, else hard_enable_TSC(); } -#endif #ifdef X86_BTS if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS)) |