diff options
| -rw-r--r-- | arch/i386/kernel/process.c | 73 | ||||
| -rw-r--r-- | include/asm-i386/processor.h | 4 | ||||
| -rw-r--r-- | include/asm-i386/thread_info.h | 5 | ||||
| -rw-r--r-- | include/linux/seccomp.h | 10 | ||||
| -rw-r--r-- | kernel/seccomp.c | 3 |
5 files changed, 50 insertions, 45 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 06dfa65ad18..6c49acb9698 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -538,8 +538,31 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) return 1; } -static noinline void __switch_to_xtra(struct task_struct *next_p, - struct tss_struct *tss) +#ifdef CONFIG_SECCOMP +void hard_disable_TSC(void) +{ + write_cr4(read_cr4() | X86_CR4_TSD); +} +void disable_TSC(void) +{ + preempt_disable(); + if (!test_and_set_thread_flag(TIF_NOTSC)) + /* + * Must flip the CPU state synchronously with + * TIF_NOTSC in the current running context. + */ + hard_disable_TSC(); + preempt_enable(); +} +void hard_enable_TSC(void) +{ + write_cr4(read_cr4() & ~X86_CR4_TSD); +} +#endif /* CONFIG_SECCOMP */ + +static noinline void +__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, + struct tss_struct *tss) { struct thread_struct *next; @@ -555,6 +578,17 @@ static noinline void __switch_to_xtra(struct task_struct *next_p, set_debugreg(next->debugreg[7], 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 */ + if (test_tsk_thread_flag(next_p, TIF_NOTSC)) + hard_disable_TSC(); + else + hard_enable_TSC(); + } +#endif + if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { /* * Disable the bitmap via an invalid offset. We still cache @@ -586,33 +620,6 @@ static noinline void __switch_to_xtra(struct task_struct *next_p, } /* - * This function selects if the context switch from prev to next - * has to tweak the TSC disable bit in the cr4. - */ -static inline void disable_tsc(struct task_struct *prev_p, - struct task_struct *next_p) -{ - struct thread_info *prev, *next; - - /* - * gcc should eliminate the ->thread_info dereference if - * has_secure_computing returns 0 at compile time (SECCOMP=n). - */ - prev = task_thread_info(prev_p); - next = task_thread_info(next_p); - - if (has_secure_computing(prev) || has_secure_computing(next)) { - /* slow path here */ - if (has_secure_computing(prev) && - !has_secure_computing(next)) { - write_cr4(read_cr4() & ~X86_CR4_TSD); - } else if (!has_secure_computing(prev) && - has_secure_computing(next)) - write_cr4(read_cr4() | X86_CR4_TSD); - } -} - -/* * switch_to(x,yn) should switch tasks from x to y. * * We fsave/fwait so that an exception goes off at the right time @@ -689,11 +696,9 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas /* * Now maybe handle debug registers and/or IO bitmaps */ - if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW) - || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))) - __switch_to_xtra(next_p, tss); - - disable_tsc(prev_p, next_p); + if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || + task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) + __switch_to_xtra(prev_p, next_p, tss); /* * Leave lazy mode, flushing any hypercalls made here. diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 94e0c147c16..422cffef00c 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -228,6 +228,10 @@ extern int bootloader_type; #define HAVE_ARCH_PICK_MMAP_LAYOUT +extern void hard_disable_TSC(void); +extern void disable_TSC(void); +extern void hard_enable_TSC(void); + /* * Size of io_bitmap. */ diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h index 4cb0f91ae64..54424e045e0 100644 --- a/include/asm-i386/thread_info.h +++ b/include/asm-i386/thread_info.h @@ -137,6 +137,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_DEBUG 17 /* uses debug registers */ #define TIF_IO_BITMAP 18 /* uses I/O bitmap */ #define TIF_FREEZE 19 /* is freezing for suspend */ +#define TIF_NOTSC 20 /* TSC is not accessible in userland */ #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) #define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME) @@ -151,6 +152,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_DEBUG (1<<TIF_DEBUG) #define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP) #define _TIF_FREEZE (1<<TIF_FREEZE) +#define _TIF_NOTSC (1<<TIF_NOTSC) /* work to do on interrupt/exception return */ #define _TIF_WORK_MASK \ @@ -160,7 +162,8 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP) /* flags to check in __switch_to() */ -#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP) +#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG) +#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC) /* * Thread-synchronous status. diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index d708974dbfe..262a8dccfa8 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -16,11 +16,6 @@ static inline void secure_computing(int this_syscall) __secure_computing(this_syscall); } -static inline int has_secure_computing(struct thread_info *ti) -{ - return unlikely(test_ti_thread_flag(ti, TIF_SECCOMP)); -} - extern long prctl_get_seccomp(void); extern long prctl_set_seccomp(unsigned long); @@ -29,11 +24,6 @@ extern long prctl_set_seccomp(unsigned long); typedef struct { } seccomp_t; #define secure_computing(x) do { } while (0) -/* static inline to preserve typechecking */ -static inline int has_secure_computing(struct thread_info *ti) -{ - return 0; -} static inline long prctl_get_seccomp(void) { diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 1dfa8a50972..ad64fcb731f 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -74,6 +74,9 @@ long prctl_set_seccomp(unsigned long seccomp_mode) if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) { current->seccomp.mode = seccomp_mode; set_thread_flag(TIF_SECCOMP); +#ifdef TIF_NOTSC + disable_TSC(); +#endif ret = 0; } |