Commit b332828c authored by K.Prasad's avatar K.Prasad Committed by Frederic Weisbecker
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hw-breakpoints: prepare the code for Hardware Breakpoint interfaces 



The generic hardware breakpoint interface provides an abstraction of
hardware breakpoints in front of specific arch implementations for both kernel
and user side breakpoints.
This includes execution breakpoints and read/write breakpoints, also known as
"watchpoints".

This patch introduces header files containing constants, structure definitions
and declaration of functions used by the hardware breakpoint core and x86
specific code.
It also introduces an array based storage for the debug-register values in
'struct thread_struct', while modifying all users of debugreg<n> member in the
structure.

[ Impact: add headers for new hardware breakpoint interface ]

Original-patch-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarK.Prasad <prasad@linux.vnet.ibm.com>
Reviewed-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 43bd1236

arch/x86/include/asm/a.out-core.h

+4 −4
Original line number Diff line number Diff line
@@ -32,10 +32,10 @@ static inline void aout_dump_thread(struct pt_regs *regs, struct user *dump) 
			>> PAGE_SHIFT;

	dump->u_dsize -= dump->u_tsize;

	dump->u_ssize = 0;

	dump->u_debugreg[0] = current->thread.debugreg0;

	dump->u_debugreg[1] = current->thread.debugreg1;

	dump->u_debugreg[2] = current->thread.debugreg2;

	dump->u_debugreg[3] = current->thread.debugreg3;

	dump->u_debugreg[0] = current->thread.debugreg[0];

	dump->u_debugreg[1] = current->thread.debugreg[1];

	dump->u_debugreg[2] = current->thread.debugreg[2];

	dump->u_debugreg[3] = current->thread.debugreg[3];

	dump->u_debugreg[4] = 0;

	dump->u_debugreg[5] = 0;

	dump->u_debugreg[6] = current->thread.debugreg6;

arch/x86/include/asm/debugreg.h

+29 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#define DR_TRAP1	(0x2)		/* db1 */

#define DR_TRAP2	(0x4)		/* db2 */

#define DR_TRAP3	(0x8)		/* db3 */

#define DR_TRAP_BITS	(DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)



#define DR_STEP		(0x4000)	/* single-step */

#define DR_SWITCH	(0x8000)	/* task switch */
@@ -49,6 +50,8 @@ 


#define DR_LOCAL_ENABLE_SHIFT 0    /* Extra shift to the local enable bit */

#define DR_GLOBAL_ENABLE_SHIFT 1   /* Extra shift to the global enable bit */

#define DR_LOCAL_ENABLE (0x1)      /* Local enable for reg 0 */

#define DR_GLOBAL_ENABLE (0x2)     /* Global enable for reg 0 */

#define DR_ENABLE_SIZE 2           /* 2 enable bits per register */



#define DR_LOCAL_ENABLE_MASK (0x55)  /* Set  local bits for all 4 regs */
@@ -67,4 +70,30 @@ 
#define DR_LOCAL_SLOWDOWN (0x100)   /* Local slow the pipeline */

#define DR_GLOBAL_SLOWDOWN (0x200)  /* Global slow the pipeline */



/*

 * HW breakpoint additions

 */

#ifdef __KERNEL__



/* For process management */

extern void flush_thread_hw_breakpoint(struct task_struct *tsk);

extern int copy_thread_hw_breakpoint(struct task_struct *tsk,

		struct task_struct *child, unsigned long clone_flags);



/* For CPU management */

extern void load_debug_registers(void);

static inline void hw_breakpoint_disable(void)

{

	/* Zero the control register for HW Breakpoint */

	set_debugreg(0UL, 7);



	/* Zero-out the individual HW breakpoint address registers */

	set_debugreg(0UL, 0);

	set_debugreg(0UL, 1);

	set_debugreg(0UL, 2);

	set_debugreg(0UL, 3);

}



#endif	/* __KERNEL__ */



#endif /* _ASM_X86_DEBUGREG_H */

arch/x86/include/asm/hw_breakpoint.h

0 → 100644
+55 −0
Original line number Diff line number Diff line 
#ifndef	_I386_HW_BREAKPOINT_H

#define	_I386_HW_BREAKPOINT_H



#ifdef	__KERNEL__

#define	__ARCH_HW_BREAKPOINT_H



struct arch_hw_breakpoint {

	char		*name; /* Contains name of the symbol to set bkpt */

	unsigned long	address;

	u8		len;

	u8		type;

};



#include <linux/kdebug.h>

#include <asm-generic/hw_breakpoint.h>



/* Available HW breakpoint length encodings */

#define HW_BREAKPOINT_LEN_1		0x40

#define HW_BREAKPOINT_LEN_2		0x44

#define HW_BREAKPOINT_LEN_4		0x4c

#define HW_BREAKPOINT_LEN_EXECUTE	0x40



#ifdef CONFIG_X86_64

#define HW_BREAKPOINT_LEN_8		0x48

#endif



/* Available HW breakpoint type encodings */



/* trigger on instruction execute */

#define HW_BREAKPOINT_EXECUTE	0x80

/* trigger on memory write */

#define HW_BREAKPOINT_WRITE	0x81

/* trigger on memory read or write */

#define HW_BREAKPOINT_RW	0x83



/* Total number of available HW breakpoint registers */

#define HBP_NUM 4



extern struct hw_breakpoint *hbp_kernel[HBP_NUM];

DECLARE_PER_CPU(struct hw_breakpoint*, this_hbp_kernel[HBP_NUM]);

extern unsigned int hbp_user_refcount[HBP_NUM];



extern void arch_install_thread_hw_breakpoint(struct task_struct *tsk);

extern void arch_uninstall_thread_hw_breakpoint(void);

extern int arch_check_va_in_userspace(unsigned long va, u8 hbp_len);

extern int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp,

						struct task_struct *tsk);

extern void arch_update_user_hw_breakpoint(int pos, struct task_struct *tsk);

extern void arch_flush_thread_hw_breakpoint(struct task_struct *tsk);

extern void arch_update_kernel_hw_breakpoint(void *);

extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,

				     unsigned long val, void *data);

#endif	/* __KERNEL__ */

#endif	/* _I386_HW_BREAKPOINT_H */

arch/x86/include/asm/processor.h

+4 −4
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ struct mm_struct; 
#include <linux/threads.h>

#include <linux/init.h>



#define HBP_NUM 4

/*

 * Default implementation of macro that returns current

 * instruction pointer ("program counter").
@@ -431,12 +432,11 @@ struct thread_struct { 
	unsigned long		fs;

	unsigned long		gs;

	/* Hardware debugging registers: */

	unsigned long		debugreg0;

	unsigned long		debugreg1;

	unsigned long		debugreg2;

	unsigned long		debugreg3;

	unsigned long		debugreg[HBP_NUM];

	unsigned long		debugreg6;

	unsigned long		debugreg7;

	/* Hardware breakpoint info */

	struct hw_breakpoint	*hbp[HBP_NUM];

	/* Fault info: */

	unsigned long		cr2;

	unsigned long		trap_no;

arch/x86/kernel/process.c

+8 −8
Original line number Diff line number Diff line
@@ -106,10 +106,10 @@ void flush_thread(void) 


	clear_tsk_thread_flag(tsk, TIF_DEBUG);



	tsk->thread.debugreg0 = 0;

	tsk->thread.debugreg1 = 0;

	tsk->thread.debugreg2 = 0;

	tsk->thread.debugreg3 = 0;

	tsk->thread.debugreg[0] = 0;

	tsk->thread.debugreg[1] = 0;

	tsk->thread.debugreg[2] = 0;

	tsk->thread.debugreg[3] = 0;

	tsk->thread.debugreg6 = 0;

	tsk->thread.debugreg7 = 0;

	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
@@ -194,10 +194,10 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, 
		update_debugctlmsr(next->debugctlmsr);



	if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {

		set_debugreg(next->debugreg0, 0);

		set_debugreg(next->debugreg1, 1);

		set_debugreg(next->debugreg2, 2);

		set_debugreg(next->debugreg3, 3);

		set_debugreg(next->debugreg[0], 0);

		set_debugreg(next->debugreg[1], 1);

		set_debugreg(next->debugreg[2], 2);

		set_debugreg(next->debugreg[3], 3);

		/* no 4 and 5 */

		set_debugreg(next->debugreg6, 6);

		set_debugreg(next->debugreg7, 7);

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