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Commit 7e991604 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

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: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 0a049bb0

arch/x86/kernel/process_32.c

+5 −1
Original line number Diff line number Diff line
@@ -602,10 +602,14 @@ 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);

arch/x86/kernel/process_64.c

+3 −0
Original line number Diff line number Diff line
@@ -555,6 +555,9 @@ 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);

include/asm-x86/processor_32.h

+2 −0
Original line number Diff line number Diff line
@@ -368,6 +368,8 @@ 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  {							\

include/asm-x86/processor_64.h

+2 −0
Original line number Diff line number Diff line
@@ -238,6 +238,8 @@ 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)));

include/asm-x86/thread_info_32.h

+4 −2
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ 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)
@@ -155,6 +156,7 @@ 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 \
@@ -164,8 +166,8 @@ 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.