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#include <asm/opcodes.h>
15
16/*
17 * GDB assumes that we're a user process being debugged, so
18 * it will send us an SWI command to write into memory as the
19 * debug trap. When an SWI occurs, the next instruction addr is
20 * placed into R14_svc before jumping to the vector trap.
21 * This doesn't work for kernel debugging as we are already in SVC
22 * we would loose the kernel's LR, which is a bad thing. This
23 * is  bad thing.
24 *
25 * By doing this as an undefined instruction trap, we force a mode
26 * switch from SVC to UND mode, allowing us to save full kernel state.
27 *
28 * We also define a KGDB_COMPILED_BREAK which can be used to compile
29 * in breakpoints. This is important for things like sysrq-G and for
30 * the initial breakpoint from trap_init().
31 *
32 * Note to ARM HW designers: Add real trap support like SH && PPC to
33 * make our lives much much simpler. :)
34 */
35#define BREAK_INSTR_SIZE	4
36#define GDB_BREAKINST		0xef9f0001
37#define KGDB_BREAKINST		0xe7ffdefe
38#define KGDB_COMPILED_BREAK	0xe7ffdeff
39#define CACHE_FLUSH_IS_SAFE	1
40
41#ifndef	__ASSEMBLY__
42
43static inline void arch_kgdb_breakpoint(void)
44{
45	asm(__inst_arm(0xe7ffdeff));
46}
47
48extern void kgdb_handle_bus_error(void);
49extern int kgdb_fault_expected;
50
51#endif /* !__ASSEMBLY__ */
52
53/*
54 * From Kevin Hilman:
55 *
56 * gdb is expecting the following registers layout.
57 *
58 * r0-r15: 1 long word each
59 * f0-f7:  unused, 3 long words each !!
60 * fps:    unused, 1 long word
61 * cpsr:   1 long word
62 *
63 * Even though f0-f7 and fps are not used, they need to be
64 * present in the registers sent for correct processing in
65 * the host-side gdb.
66 *
67 * In particular, it is crucial that CPSR is in the right place,
68 * otherwise gdb will not be able to correctly interpret stepping over
69 * conditional branches.
70 */
71#define _GP_REGS		16
72#define _FP_REGS		8
73#define _EXTRA_REGS		2
74#define GDB_MAX_REGS		(_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
75#define DBG_MAX_REG_NUM		(_GP_REGS + _FP_REGS + _EXTRA_REGS)
76
77#define KGDB_MAX_NO_CPUS	1
78#define BUFMAX			400
79#define NUMREGBYTES		(DBG_MAX_REG_NUM << 2)
80#define NUMCRITREGBYTES		(32 << 2)
81
82#define _R0			0
83#define _R1			1
84#define _R2			2
85#define _R3			3
86#define _R4			4
87#define _R5			5
88#define _R6			6
89#define _R7			7
90#define _R8			8
91#define _R9			9
92#define _R10			10
93#define _FP			11
94#define _IP			12
95#define _SPT			13
96#define _LR			14
97#define _PC			15
98#define _CPSR			(GDB_MAX_REGS - 1)
99
100/*
101 * So that we can denote the end of a frame for tracing,
102 * in the simple case:
103 */
104#define CFI_END_FRAME(func)	__CFI_END_FRAME(_PC, _SPT, func)
105
106#endif /* __ASM_KGDB_H__ */
107