LXR linux/arch/arm/include/asm/kgdb.h

   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
  42static inline void arch_kgdb_breakpoint(void)
  43{
  44        asm(".word 0xe7ffdeff");
  45}
  46
  47extern void kgdb_handle_bus_error(void);
  48extern 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