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Commit bf53de90 authored by Markus Metzger's avatar Markus Metzger Committed by Ingo Molnar
Browse files

x86, bts: add fork and exit handling 



Impact: introduce new ptrace facility

Add arch_ptrace_untrace() function that is called when the tracer
detaches (either voluntarily or when the tracing task dies);
ptrace_disable() is only called on a voluntary detach.

Add ptrace_fork() and arch_ptrace_fork(). They are called when a
traced task is forked.

Clear DS and BTS related fields on fork.

Release DS resources and reclaim memory in ptrace_untrace(). This
releases resources already when the tracing task dies. We used to do
that when the traced task dies.

Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 30cd324e

arch/x86/include/asm/ds.h

+9 −0
Original line number Diff line number Diff line
@@ -252,12 +252,21 @@ extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *); 
 */

extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);



/*

 * Task clone/init and cleanup work

 */

extern void ds_copy_thread(struct task_struct *tsk, struct task_struct *father);

extern void ds_exit_thread(struct task_struct *tsk);



#else /* CONFIG_X86_DS */



struct cpuinfo_x86;

static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}

static inline void ds_switch_to(struct task_struct *prev,

				struct task_struct *next) {}

static inline void ds_copy_thread(struct task_struct *tsk,

				  struct task_struct *father) {}

static inline void ds_exit_thread(struct task_struct *tsk) {}



#endif /* CONFIG_X86_DS */

#endif /* _ASM_X86_DS_H */

arch/x86/include/asm/ptrace.h

+7 −0
Original line number Diff line number Diff line
@@ -235,6 +235,13 @@ extern int do_get_thread_area(struct task_struct *p, int idx, 
extern int do_set_thread_area(struct task_struct *p, int idx,

			      struct user_desc __user *info, int can_allocate);



extern void x86_ptrace_untrace(struct task_struct *);

extern void x86_ptrace_fork(struct task_struct *child,

			    unsigned long clone_flags);



#define arch_ptrace_untrace(tsk) x86_ptrace_untrace(tsk)

#define arch_ptrace_fork(child, flags) x86_ptrace_fork(child, flags)



#endif /* __KERNEL__ */



#endif /* !__ASSEMBLY__ */

arch/x86/kernel/ds.c

+11 −0
Original line number Diff line number Diff line
@@ -1017,3 +1017,14 @@ void ds_switch_to(struct task_struct *prev, struct task_struct *next) 


	update_debugctlmsr(next->thread.debugctlmsr);

}



void ds_copy_thread(struct task_struct *tsk, struct task_struct *father)

{

	clear_tsk_thread_flag(tsk, TIF_DS_AREA_MSR);

	tsk->thread.ds_ctx = NULL;

}



void ds_exit_thread(struct task_struct *tsk)

{

	WARN_ON(tsk->thread.ds_ctx);

}

arch/x86/kernel/process_32.c

+9 −11
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#include <asm/idle.h>

#include <asm/syscalls.h>

#include <asm/smp.h>

#include <asm/ds.h>



asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@@ -251,17 +252,8 @@ void exit_thread(void) 
		tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;

		put_cpu();

	}

#ifdef CONFIG_X86_DS

	/* Free any BTS tracers that have not been properly released. */

	if (unlikely(current->bts)) {

		ds_release_bts(current->bts);

		current->bts = NULL;



		kfree(current->bts_buffer);

		current->bts_buffer = NULL;

		current->bts_size = 0;

	}

#endif /* CONFIG_X86_DS */

	ds_exit_thread(current);

}



void flush_thread(void)
@@ -343,6 +335,12 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, 
		kfree(p->thread.io_bitmap_ptr);

		p->thread.io_bitmap_max = 0;

	}



	ds_copy_thread(p, current);



	clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);

	p->thread.debugctlmsr = 0;



	return err;

}

arch/x86/kernel/process_64.c

+9 −11
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
#include <asm/ia32.h>

#include <asm/idle.h>

#include <asm/syscalls.h>

#include <asm/ds.h>



asmlinkage extern void ret_from_fork(void);
@@ -236,17 +237,8 @@ void exit_thread(void) 
		t->io_bitmap_max = 0;

		put_cpu();

	}

#ifdef CONFIG_X86_DS

	/* Free any BTS tracers that have not been properly released. */

	if (unlikely(current->bts)) {

		ds_release_bts(current->bts);

		current->bts = NULL;



		kfree(current->bts_buffer);

		current->bts_buffer = NULL;

		current->bts_size = 0;

	}

#endif /* CONFIG_X86_DS */

	ds_exit_thread(current);

}



void flush_thread(void)
@@ -376,6 +368,12 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, 
		if (err)

			goto out;

	}



	ds_copy_thread(p, me);



	clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);

	p->thread.debugctlmsr = 0;



	err = 0;

out:

	if (err && p->thread.io_bitmap_ptr) {