1 /*
2 * ARM KGDB support
3 *
4 * Author: Deepak Saxena <dsaxena@mvista.com>
5 *
6 * Copyright (C) 2002 MontaVista Software Inc.
7 *
8 */
9
10 #ifndef __ARM_KGDB_H__
11 #define __ARM_KGDB_H__
12
13 #include <linux/ptrace.h>
14
15 /*
16 * GDB assumes that we're a user process being debugged, so
17 * it will send us an SWI command to write into memory as the
18 * debug trap. When an SWI occurs, the next instruction addr is
19 * placed into R14_svc before jumping to the vector trap.
20 * This doesn't work for kernel debugging as we are already in SVC
21 * we would loose the kernel's LR, which is a bad thing. This
22 * is bad thing.
23 *
24 * By doing this as an undefined instruction trap, we force a mode
25 * switch from SVC to UND mode, allowing us to save full kernel state.
26 *
27 * We also define a KGDB_COMPILED_BREAK which can be used to compile
28 * in breakpoints. This is important for things like sysrq-G and for
29 * the initial breakpoint from trap_init().
30 *
31 * Note to ARM HW designers: Add real trap support like SH && PPC to
32 * make our lives much much simpler. :)
33 */
34 #define BREAK_INSTR_SIZE 4
35 #define GDB_BREAKINST 0xef9f0001
36 #define KGDB_BREAKINST 0xe7ffdefe
37 #define KGDB_COMPILED_BREAK 0xe7ffdeff
38 #define CACHE_FLUSH_IS_SAFE 1
39
40 #ifndef __ASSEMBLY__
41
arch_kgdb_breakpoint(void)42 static inline void arch_kgdb_breakpoint(void)
43 {
44 asm(".word 0xe7ffdeff");
45 }
46
47 extern void kgdb_handle_bus_error(void);
48 extern int kgdb_fault_expected;
49
50 #endif /* !__ASSEMBLY__ */
51
52 /*
53 * From Kevin Hilman:
54 *
55 * gdb is expecting the following registers layout.
56 *
57 * r0-r15: 1 long word each
58 * f0-f7: unused, 3 long words each !!
59 * fps: unused, 1 long word
60 * cpsr: 1 long word
61 *
62 * Even though f0-f7 and fps are not used, they need to be
63 * present in the registers sent for correct processing in
64 * the host-side gdb.
65 *
66 * In particular, it is crucial that CPSR is in the right place,
67 * otherwise gdb will not be able to correctly interpret stepping over
68 * conditional branches.
69 */
70 #define _GP_REGS 16
71 #define _FP_REGS 8
72 #define _EXTRA_REGS 2
73 #define GDB_MAX_REGS (_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
74 #define DBG_MAX_REG_NUM (_GP_REGS + _FP_REGS + _EXTRA_REGS)
75
76 #define KGDB_MAX_NO_CPUS 1
77 #define BUFMAX 400
78 #define NUMREGBYTES (DBG_MAX_REG_NUM << 2)
79 #define NUMCRITREGBYTES (32 << 2)
80
81 #define _R0 0
82 #define _R1 1
83 #define _R2 2
84 #define _R3 3
85 #define _R4 4
86 #define _R5 5
87 #define _R6 6
88 #define _R7 7
89 #define _R8 8
90 #define _R9 9
91 #define _R10 10
92 #define _FP 11
93 #define _IP 12
94 #define _SPT 13
95 #define _LR 14
96 #define _PC 15
97 #define _CPSR (GDB_MAX_REGS - 1)
98
99 /*
100 * So that we can denote the end of a frame for tracing,
101 * in the simple case:
102 */
103 #define CFI_END_FRAME(func) __CFI_END_FRAME(_PC, _SPT, func)
104
105 #endif /* __ASM_KGDB_H__ */
106