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debugreg.h
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1 #ifndef _ASM_X86_DEBUGREG_H
2 #define _ASM_X86_DEBUGREG_H
3 
4 
5 /* Indicate the register numbers for a number of the specific
6  debug registers. Registers 0-3 contain the addresses we wish to trap on */
7 #define DR_FIRSTADDR 0 /* u_debugreg[DR_FIRSTADDR] */
8 #define DR_LASTADDR 3 /* u_debugreg[DR_LASTADDR] */
9 
10 #define DR_STATUS 6 /* u_debugreg[DR_STATUS] */
11 #define DR_CONTROL 7 /* u_debugreg[DR_CONTROL] */
12 
13 /* Define a few things for the status register. We can use this to determine
14  which debugging register was responsible for the trap. The other bits
15  are either reserved or not of interest to us. */
16 
17 /* Define reserved bits in DR6 which are always set to 1 */
18 #define DR6_RESERVED (0xFFFF0FF0)
19 
20 #define DR_TRAP0 (0x1) /* db0 */
21 #define DR_TRAP1 (0x2) /* db1 */
22 #define DR_TRAP2 (0x4) /* db2 */
23 #define DR_TRAP3 (0x8) /* db3 */
24 #define DR_TRAP_BITS (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)
25 
26 #define DR_STEP (0x4000) /* single-step */
27 #define DR_SWITCH (0x8000) /* task switch */
28 
29 /* Now define a bunch of things for manipulating the control register.
30  The top two bytes of the control register consist of 4 fields of 4
31  bits - each field corresponds to one of the four debug registers,
32  and indicates what types of access we trap on, and how large the data
33  field is that we are looking at */
34 
35 #define DR_CONTROL_SHIFT 16 /* Skip this many bits in ctl register */
36 #define DR_CONTROL_SIZE 4 /* 4 control bits per register */
37 
38 #define DR_RW_EXECUTE (0x0) /* Settings for the access types to trap on */
39 #define DR_RW_WRITE (0x1)
40 #define DR_RW_READ (0x3)
41 
42 #define DR_LEN_1 (0x0) /* Settings for data length to trap on */
43 #define DR_LEN_2 (0x4)
44 #define DR_LEN_4 (0xC)
45 #define DR_LEN_8 (0x8)
46 
47 /* The low byte to the control register determine which registers are
48  enabled. There are 4 fields of two bits. One bit is "local", meaning
49  that the processor will reset the bit after a task switch and the other
50  is global meaning that we have to explicitly reset the bit. With linux,
51  you can use either one, since we explicitly zero the register when we enter
52  kernel mode. */
53 
54 #define DR_LOCAL_ENABLE_SHIFT 0 /* Extra shift to the local enable bit */
55 #define DR_GLOBAL_ENABLE_SHIFT 1 /* Extra shift to the global enable bit */
56 #define DR_LOCAL_ENABLE (0x1) /* Local enable for reg 0 */
57 #define DR_GLOBAL_ENABLE (0x2) /* Global enable for reg 0 */
58 #define DR_ENABLE_SIZE 2 /* 2 enable bits per register */
59 
60 #define DR_LOCAL_ENABLE_MASK (0x55) /* Set local bits for all 4 regs */
61 #define DR_GLOBAL_ENABLE_MASK (0xAA) /* Set global bits for all 4 regs */
62 
63 /* The second byte to the control register has a few special things.
64  We can slow the instruction pipeline for instructions coming via the
65  gdt or the ldt if we want to. I am not sure why this is an advantage */
66 
67 #ifdef __i386__
68 #define DR_CONTROL_RESERVED (0xFC00) /* Reserved by Intel */
69 #else
70 #define DR_CONTROL_RESERVED (0xFFFFFFFF0000FC00UL) /* Reserved */
71 #endif
72 
73 #define DR_LOCAL_SLOWDOWN (0x100) /* Local slow the pipeline */
74 #define DR_GLOBAL_SLOWDOWN (0x200) /* Global slow the pipeline */
75 
76 /*
77  * HW breakpoint additions
78  */
79 #ifdef __KERNEL__
80 
81 #include <linux/bug.h>
82 
83 DECLARE_PER_CPU(unsigned long, cpu_dr7);
84 
85 #ifndef CONFIG_PARAVIRT
86 /*
87  * These special macros can be used to get or set a debugging register
88  */
89 #define get_debugreg(var, register) \
90  (var) = native_get_debugreg(register)
91 #define set_debugreg(value, register) \
92  native_set_debugreg(register, value)
93 #endif
94 
95 static inline unsigned long native_get_debugreg(int regno)
96 {
97  unsigned long val = 0; /* Damn you, gcc! */
98 
99  switch (regno) {
100  case 0:
101  asm("mov %%db0, %0" :"=r" (val));
102  break;
103  case 1:
104  asm("mov %%db1, %0" :"=r" (val));
105  break;
106  case 2:
107  asm("mov %%db2, %0" :"=r" (val));
108  break;
109  case 3:
110  asm("mov %%db3, %0" :"=r" (val));
111  break;
112  case 6:
113  asm("mov %%db6, %0" :"=r" (val));
114  break;
115  case 7:
116  asm("mov %%db7, %0" :"=r" (val));
117  break;
118  default:
119  BUG();
120  }
121  return val;
122 }
123 
124 static inline void native_set_debugreg(int regno, unsigned long value)
125 {
126  switch (regno) {
127  case 0:
128  asm("mov %0, %%db0" ::"r" (value));
129  break;
130  case 1:
131  asm("mov %0, %%db1" ::"r" (value));
132  break;
133  case 2:
134  asm("mov %0, %%db2" ::"r" (value));
135  break;
136  case 3:
137  asm("mov %0, %%db3" ::"r" (value));
138  break;
139  case 6:
140  asm("mov %0, %%db6" ::"r" (value));
141  break;
142  case 7:
143  asm("mov %0, %%db7" ::"r" (value));
144  break;
145  default:
146  BUG();
147  }
148 }
149 
150 static inline void hw_breakpoint_disable(void)
151 {
152  /* Zero the control register for HW Breakpoint */
153  set_debugreg(0UL, 7);
154 
155  /* Zero-out the individual HW breakpoint address registers */
156  set_debugreg(0UL, 0);
157  set_debugreg(0UL, 1);
158  set_debugreg(0UL, 2);
159  set_debugreg(0UL, 3);
160 }
161 
162 static inline int hw_breakpoint_active(void)
163 {
164  return __this_cpu_read(cpu_dr7) & DR_GLOBAL_ENABLE_MASK;
165 }
166 
167 extern void aout_dump_debugregs(struct user *dump);
168 
169 extern void hw_breakpoint_restore(void);
170 
171 #ifdef CONFIG_X86_64
172 DECLARE_PER_CPU(int, debug_stack_usage);
173 static inline void debug_stack_usage_inc(void)
174 {
175  __get_cpu_var(debug_stack_usage)++;
176 }
177 static inline void debug_stack_usage_dec(void)
178 {
179  __get_cpu_var(debug_stack_usage)--;
180 }
181 int is_debug_stack(unsigned long addr);
182 void debug_stack_set_zero(void);
183 void debug_stack_reset(void);
184 #else /* !X86_64 */
185 static inline int is_debug_stack(unsigned long addr) { return 0; }
186 static inline void debug_stack_set_zero(void) { }
187 static inline void debug_stack_reset(void) { }
188 static inline void debug_stack_usage_inc(void) { }
189 static inline void debug_stack_usage_dec(void) { }
190 #endif /* X86_64 */
191 
192 
193 #endif /* __KERNEL__ */
194 
195 #endif /* _ASM_X86_DEBUGREG_H */