This patch introduces header files containing constants, structure definitions and declaration of functions used by the hardware breakpoint interface code. Signed-off-by: K.Prasad Signed-off-by: Alan Stern --- arch/x86/include/asm/debugreg.h | 31 +++++++ arch/x86/include/asm/hw_breakpoint.h | 66 ++++++++++++++++ arch/x86/include/asm/processor.h | 4 + include/asm-generic/hw_breakpoint.h | 139 +++++++++++++++++++++++++++++++++++ 4 files changed, 240 insertions(+) Index: include/asm-generic/hw_breakpoint.h =================================================================== --- /dev/null +++ include/asm-generic/hw_breakpoint.h @@ -0,0 +1,139 @@ +#ifndef _ASM_GENERIC_HW_BREAKPOINT_H +#define _ASM_GENERIC_HW_BREAKPOINT_H + +#ifndef __ARCH_HW_BREAKPOINT_H +#error "Please don't include this file directly" +#endif + +#ifdef __KERNEL__ +#include +#include +#include + +/** + * struct hw_breakpoint - unified kernel/user-space hardware breakpoint + * @triggered: callback invoked after target address access + * @info: arch-specific breakpoint info (address, length, and type) + * + * %hw_breakpoint structures are the kernel's way of representing + * hardware breakpoints. These are data breakpoints + * (also known as "watchpoints", triggered on data access), and the breakpoint's + * target address can be located in either kernel space or user space. + * + * The breakpoint's address, length, and type are highly + * architecture-specific. The values are encoded in the @info field; you + * specify them when registering the breakpoint. To examine the encoded + * values use hw_breakpoint_get_{kaddress,uaddress,len,type}(), declared + * below. + * + * The address is specified as a regular kernel pointer (for kernel-space + * breakponts) or as an %__user pointer (for user-space breakpoints). + * With register_user_hw_breakpoint(), the address must refer to a + * location in user space. The breakpoint will be active only while the + * requested task is running. Conversely with + * register_kernel_hw_breakpoint(), the address must refer to a location + * in kernel space, and the breakpoint will be active on all CPUs + * regardless of the current task. + * + * The length is the breakpoint's extent in bytes, which is subject to + * certain limitations. include/asm/hw_breakpoint.h contains macros + * defining the available lengths for a specific architecture. Note that + * the address's alignment must match the length. The breakpoint will + * catch accesses to any byte in the range from address to address + + * (length - 1). + * + * The breakpoint's type indicates the sort of access that will cause it + * to trigger. Possible values may include: + * + * %HW_BREAKPOINT_RW (triggered on read or write access), + * %HW_BREAKPOINT_WRITE (triggered on write access), and + * %HW_BREAKPOINT_READ (triggered on read access). + * + * Appropriate macros are defined in include/asm/hw_breakpoint.h; not all + * possibilities are available on all architectures. Execute breakpoints + * must have length equal to the special value %HW_BREAKPOINT_LEN_EXECUTE. + * + * When a breakpoint gets hit, the @triggered callback is + * invoked in_interrupt with a pointer to the %hw_breakpoint structure and the + * processor registers. + * Data breakpoints occur after the memory access has taken place. + * Breakpoints are disabled during execution @triggered, to avoid + * recursive traps and allow unhindered access to breakpointed memory. + * + * This sample code sets a breakpoint on pid_max and registers a callback + * function for writes to that variable. Note that it is not portable + * as written, because not all architectures support HW_BREAKPOINT_LEN_4. + * + * ---------------------------------------------------------------------- + * + * #include + * + * struct hw_breakpoint my_bp; + * + * static void my_triggered(struct hw_breakpoint *bp, struct pt_regs *regs) + * { + * printk(KERN_DEBUG "Inside triggered routine of breakpoint exception\n"); + * dump_stack(); + * ............... + * } + * + * static struct hw_breakpoint my_bp; + * + * static int init_module(void) + * { + * ...................... + * my_bp.info.type = HW_BREAKPOINT_WRITE; + * my_bp.info.len = HW_BREAKPOINT_LEN_4; + * + * my_bp.installed = (void *)my_bp_installed; + * + * rc = register_kernel_hw_breakpoint(&my_bp); + * ...................... + * } + * + * static void cleanup_module(void) + * { + * ...................... + * unregister_kernel_hw_breakpoint(&my_bp); + * ...................... + * } + * + * ---------------------------------------------------------------------- + */ +struct hw_breakpoint { + void (*triggered)(struct hw_breakpoint *, struct pt_regs *); + struct arch_hw_breakpoint info; +}; + +/* + * len and type values are defined in include/asm/hw_breakpoint.h. + * Available values vary according to the architecture. On i386 the + * possibilities are: + * + * HW_BREAKPOINT_LEN_1 + * HW_BREAKPOINT_LEN_2 + * HW_BREAKPOINT_LEN_4 + * HW_BREAKPOINT_RW + * HW_BREAKPOINT_READ + * + * On other architectures HW_BREAKPOINT_LEN_8 may be available, and the + * 1-, 2-, and 4-byte lengths may be unavailable. There also may be + * HW_BREAKPOINT_WRITE. You can use #ifdef to check at compile time. + */ + +int register_user_hw_breakpoint(struct task_struct *tsk, + struct hw_breakpoint *bp); +void unregister_user_hw_breakpoint(struct task_struct *tsk, + struct hw_breakpoint *bp); +/* + * Kernel breakpoints are not associated with any particular thread. + */ +int register_kernel_hw_breakpoint(struct hw_breakpoint *bp); +void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp); +void switch_to_none_hw_breakpoint(void); + +extern unsigned int hbp_kernel_pos; +extern spinlock_t hw_breakpoint_lock; + +#endif /* __KERNEL__ */ +#endif /* _ASM_GENERIC_HW_BREAKPOINT_H */ Index: arch/x86/include/asm/hw_breakpoint.h =================================================================== --- /dev/null +++ arch/x86/include/asm/hw_breakpoint.h @@ -0,0 +1,66 @@ +#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 +#include + +/* 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 HB_NUM 4 + +extern struct hw_breakpoint *hbp_kernel[HB_NUM]; +DECLARE_PER_CPU(struct hw_breakpoint*, this_hbp_kernel[HB_NUM]); +extern unsigned int hbp_user_refcount[HB_NUM]; + +/* + * Ptrace support: breakpoint trigger routine. + */ +int __register_user_hw_breakpoint(int pos, struct task_struct *tsk, + struct hw_breakpoint *bp); +int __modify_user_hw_breakpoint(int pos, struct task_struct *tsk, + struct hw_breakpoint *bp); +void __unregister_user_hw_breakpoint(int pos, struct task_struct *tsk); + +void arch_install_thread_hw_breakpoint(struct task_struct *tsk); +void arch_uninstall_thread_hw_breakpoint(void); +int arch_check_va_in_userspace(unsigned long va, u8 hbp_len); +int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len); +int arch_validate_hwbkpt_settings(struct hw_breakpoint *bp, + struct task_struct *tsk); +void arch_update_user_hw_breakpoint(int pos, struct task_struct *tsk); +void arch_flush_thread_hw_breakpoint(struct task_struct *tsk); +void arch_update_kernel_hw_breakpoint(void *); +int hw_breakpoint_handler(struct die_args *args); +int hw_breakpoint_exceptions_notify(struct notifier_block *unused, + unsigned long val, void *data); +#endif /* __KERNEL__ */ +#endif /* _I386_HW_BREAKPOINT_H */ + Index: arch/x86/include/asm/debugreg.h =================================================================== --- arch/x86/include/asm/debugreg.h.orig +++ arch/x86/include/asm/debugreg.h @@ -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 +70,32 @@ #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 */ +void flush_thread_hw_breakpoint(struct task_struct *tsk); +int copy_thread_hw_breakpoint(struct task_struct *tsk, + struct task_struct *child, unsigned long clone_flags); +void dump_thread_hw_breakpoint(struct task_struct *tsk, int u_debugreg[8]); +void switch_to_thread_hw_breakpoint(struct task_struct *tsk); + +/* For CPU management */ +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 */ Index: arch/x86/include/asm/processor.h =================================================================== --- arch/x86/include/asm/processor.h.orig +++ arch/x86/include/asm/processor.h @@ -29,6 +29,7 @@ struct mm_struct; #include #include +#define HB_NUM 4 /* * Default implementation of macro that returns current * instruction pointer ("program counter"). @@ -435,8 +436,11 @@ struct thread_struct { unsigned long debugreg1; unsigned long debugreg2; unsigned long debugreg3; + unsigned long debugreg[HB_NUM]; unsigned long debugreg6; unsigned long debugreg7; + /* Hardware breakpoint info */ + struct hw_breakpoint *hbp[HB_NUM]; /* Fault info: */ unsigned long cr2; unsigned long trap_no; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/