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
  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__ */