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__ */