Gitiles
Code Review Sign In
gerrit-public.fairphone.software / kernel / msm-5.4 / b332828c39326b1dca617f387dd15d12e81cd5f0 / . / include / asm-generic / hw_breakpoint.h
blob: 9bf2d12eb74a5ca7be2b3685a6cedeadfed1ce18 [file] [log] [blame]
K.Prasadb332828c2009-06-01 23:43:10 +0530[diff] [blame^]1#ifndef _ASM_GENERIC_HW_BREAKPOINT_H
2#define _ASM_GENERIC_HW_BREAKPOINT_H
3
4#ifndef __ARCH_HW_BREAKPOINT_H
5#error "Please don't include this file directly"
6#endif
7
8#ifdef __KERNEL__
9#include <linux/list.h>
10#include <linux/types.h>
11#include <linux/kallsyms.h>
12
13/**
14 * struct hw_breakpoint - unified kernel/user-space hardware breakpoint
15 * @triggered: callback invoked after target address access
16 * @info: arch-specific breakpoint info (address, length, and type)
17 *
18 * %hw_breakpoint structures are the kernel's way of representing
19 * hardware breakpoints. These are data breakpoints
20 * (also known as "watchpoints", triggered on data access), and the breakpoint's
21 * target address can be located in either kernel space or user space.
22 *
23 * The breakpoint's address, length, and type are highly
24 * architecture-specific. The values are encoded in the @info field; you
25 * specify them when registering the breakpoint. To examine the encoded
26 * values use hw_breakpoint_get_{kaddress,uaddress,len,type}(), declared
27 * below.
28 *
29 * The address is specified as a regular kernel pointer (for kernel-space
30 * breakponts) or as an %__user pointer (for user-space breakpoints).
31 * With register_user_hw_breakpoint(), the address must refer to a
32 * location in user space. The breakpoint will be active only while the
33 * requested task is running. Conversely with
34 * register_kernel_hw_breakpoint(), the address must refer to a location
35 * in kernel space, and the breakpoint will be active on all CPUs
36 * regardless of the current task.
37 *
38 * The length is the breakpoint's extent in bytes, which is subject to
39 * certain limitations. include/asm/hw_breakpoint.h contains macros
40 * defining the available lengths for a specific architecture. Note that
41 * the address's alignment must match the length. The breakpoint will
42 * catch accesses to any byte in the range from address to address +
43 * (length - 1).
44 *
45 * The breakpoint's type indicates the sort of access that will cause it
46 * to trigger. Possible values may include:
47 *
48 * %HW_BREAKPOINT_RW (triggered on read or write access),
49 * %HW_BREAKPOINT_WRITE (triggered on write access), and
50 * %HW_BREAKPOINT_READ (triggered on read access).
51 *
52 * Appropriate macros are defined in include/asm/hw_breakpoint.h; not all
53 * possibilities are available on all architectures. Execute breakpoints
54 * must have length equal to the special value %HW_BREAKPOINT_LEN_EXECUTE.
55 *
56 * When a breakpoint gets hit, the @triggered callback is
57 * invoked in_interrupt with a pointer to the %hw_breakpoint structure and the
58 * processor registers.
59 * Data breakpoints occur after the memory access has taken place.
60 * Breakpoints are disabled during execution @triggered, to avoid
61 * recursive traps and allow unhindered access to breakpointed memory.
62 *
63 * This sample code sets a breakpoint on pid_max and registers a callback
64 * function for writes to that variable. Note that it is not portable
65 * as written, because not all architectures support HW_BREAKPOINT_LEN_4.
66 *
67 * ----------------------------------------------------------------------
68 *
69 * #include <asm/hw_breakpoint.h>
70 *
71 * struct hw_breakpoint my_bp;
72 *
73 * static void my_triggered(struct hw_breakpoint *bp, struct pt_regs *regs)
74 * {
75 * printk(KERN_DEBUG "Inside triggered routine of breakpoint exception\n");
76 * dump_stack();
77 * .......<more debugging output>........
78 * }
79 *
80 * static struct hw_breakpoint my_bp;
81 *
82 * static int init_module(void)
83 * {
84 * ..........<do anything>............
85 * my_bp.info.type = HW_BREAKPOINT_WRITE;
86 * my_bp.info.len = HW_BREAKPOINT_LEN_4;
87 *
88 * my_bp.installed = (void *)my_bp_installed;
89 *
90 * rc = register_kernel_hw_breakpoint(&my_bp);
91 * ..........<do anything>............
92 * }
93 *
94 * static void cleanup_module(void)
95 * {
96 * ..........<do anything>............
97 * unregister_kernel_hw_breakpoint(&my_bp);
98 * ..........<do anything>............
99 * }
100 *
101 * ----------------------------------------------------------------------
102 */
103struct hw_breakpoint {
104 void (*triggered)(struct hw_breakpoint *, struct pt_regs *);
105 struct arch_hw_breakpoint info;
106};
107
108/*
109 * len and type values are defined in include/asm/hw_breakpoint.h.
110 * Available values vary according to the architecture. On i386 the
111 * possibilities are:
112 *
113 * HW_BREAKPOINT_LEN_1
114 * HW_BREAKPOINT_LEN_2
115 * HW_BREAKPOINT_LEN_4
116 * HW_BREAKPOINT_RW
117 * HW_BREAKPOINT_READ
118 *
119 * On other architectures HW_BREAKPOINT_LEN_8 may be available, and the
120 * 1-, 2-, and 4-byte lengths may be unavailable. There also may be
121 * HW_BREAKPOINT_WRITE. You can use #ifdef to check at compile time.
122 */
123
124extern int register_user_hw_breakpoint(struct task_struct *tsk,
125 struct hw_breakpoint *bp);
126extern int modify_user_hw_breakpoint(struct task_struct *tsk,
127 struct hw_breakpoint *bp);
128extern void unregister_user_hw_breakpoint(struct task_struct *tsk,
129 struct hw_breakpoint *bp);
130/*
131 * Kernel breakpoints are not associated with any particular thread.
132 */
133extern int register_kernel_hw_breakpoint(struct hw_breakpoint *bp);
134extern void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp);
135
136extern unsigned int hbp_kernel_pos;
137
138#endif /* __KERNEL__ */
139#endif /* _ASM_GENERIC_HW_BREAKPOINT_H */