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Date: Sun, 25 Nov 2007 14:08:19 -0800 (PST) From: Roland McGrath <roland@...hat.com> To: Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org> Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com> Subject: [PATCH 24/27] x86: debugctlmsr context switch This adds low-level support for a per-thread value of MSR_IA32_DEBUGCTLMSR. The per-thread value is switched in when TIF_DEBUGCTLMSR is set. Signed-off-by: Roland McGrath <roland@...hat.com> --- arch/x86/kernel/process_32.c | 6 +++++- arch/x86/kernel/process_64.c | 3 +++ include/asm-x86/processor_32.h | 2 ++ include/asm-x86/processor_64.h | 2 ++ include/asm-x86/thread_info_32.h | 6 ++++-- include/asm-x86/thread_info_64.h | 4 +++- 6 files changed, 19 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index f59544e..3a822e3 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -581,10 +581,14 @@ static noinline void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, struct tss_struct *tss) { - struct thread_struct *next; + struct thread_struct *prev, *next; + prev = &prev_p->thread; next = &next_p->thread; + if (next->debugctlmsr != prev->debugctlmsr) + wrmsr(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr, 0); + if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { set_debugreg(next->debugreg[0], 0); set_debugreg(next->debugreg[1], 1); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 586f88e..c1e2e9a 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -544,6 +544,9 @@ static inline void __switch_to_xtra(struct task_struct *prev_p, prev = &prev_p->thread, next = &next_p->thread; + if (next->debugctlmsr != prev->debugctlmsr) + wrmsrl(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr); + if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { loaddebug(next, 0); loaddebug(next, 1); diff --git a/include/asm-x86/processor_32.h b/include/asm-x86/processor_32.h index 34e8063..660d9b0 100644 --- a/include/asm-x86/processor_32.h +++ b/include/asm-x86/processor_32.h @@ -370,6 +370,8 @@ struct thread_struct { unsigned long iopl; /* max allowed port in the bitmap, in bytes: */ unsigned long io_bitmap_max; +/* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set. */ + unsigned long debugctlmsr; }; #define INIT_THREAD { \ diff --git a/include/asm-x86/processor_64.h b/include/asm-x86/processor_64.h index 2dd739a..1d6daa0 100644 --- a/include/asm-x86/processor_64.h +++ b/include/asm-x86/processor_64.h @@ -239,6 +239,8 @@ struct thread_struct { int ioperm; unsigned long *io_bitmap_ptr; unsigned io_bitmap_max; +/* MSR_IA32_DEBUGCTLMSR value to switch in if TIF_DEBUGCTLMSR is set. */ + unsigned long debugctlmsr; /* cached TLS descriptors. */ u64 tls_array[GDT_ENTRY_TLS_ENTRIES]; } __attribute__((aligned(16))); diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h index 8a6483f..d5ae1e9 100644 --- a/include/asm-x86/thread_info_32.h +++ b/include/asm-x86/thread_info_32.h @@ -138,6 +138,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_FREEZE 19 /* is freezing for suspend */ #define TIF_NOTSC 20 /* TSC is not accessible in userland */ #define TIF_FORCED_TF 21 /* true if TF in eflags artificially */ +#define TIF_DEBUGCTLMSR 22 /* uses thread_struct.debugctlmsr */ #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) #define _TIF_SIGPENDING (1<<TIF_SIGPENDING) @@ -153,6 +154,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_FREEZE (1<<TIF_FREEZE) #define _TIF_NOTSC (1<<TIF_NOTSC) #define _TIF_FORCED_TF (1<<TIF_FORCED_TF) +#define _TIF_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR) /* work to do on interrupt/exception return */ #define _TIF_WORK_MASK \ @@ -162,8 +164,8 @@ 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_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG) -#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC) +#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG | _TIF_DEBUGCTLMSR) +#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUGCTLMSR) /* * Thread-synchronous status. diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h index 0ebcac4..8f36bbc 100644 --- a/include/asm-x86/thread_info_64.h +++ b/include/asm-x86/thread_info_64.h @@ -123,6 +123,7 @@ static inline struct thread_info *stack_thread_info(void) #define TIF_DEBUG 21 /* uses debug registers */ #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ #define TIF_FREEZE 23 /* is freezing for suspend */ +#define TIF_DEBUGCTLMSR 24 /* uses thread_struct.debugctlmsr */ #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) #define _TIF_SIGPENDING (1<<TIF_SIGPENDING) @@ -140,6 +141,7 @@ static inline struct thread_info *stack_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_DEBUGCTLMSR (1<<TIF_DEBUGCTLMSR) /* work to do on interrupt/exception return */ #define _TIF_WORK_MASK \ @@ -148,7 +150,7 @@ static inline struct thread_info *stack_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 (_TIF_DEBUG|_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR) #define PREEMPT_ACTIVE 0x10000000 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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