arch/arm/include/asm/kgdb.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * ARM KGDB support
   4  *
   5  * Author: Deepak Saxena <dsaxena@mvista.com>
   6  *
   7  * Copyright (C) 2002 MontaVista Software Inc.
   8  *
   9  */
  10
  11 #ifndef __ARM_KGDB_H__
  12 #define __ARM_KGDB_H__
  13
  14 #include <linux/ptrace.h>
  15 #include <asm/opcodes.h>
  16
  17 /*
  18  * GDB assumes that we're a user process being debugged, so
  19  * it will send us an SWI command to write into memory as the
  20  * debug trap. When an SWI occurs, the next instruction addr is
  21  * placed into R14_svc before jumping to the vector trap.
  22  * This doesn't work for kernel debugging as we are already in SVC
  23  * we would loose the kernel's LR, which is a bad thing. This
  24  * is  bad thing.
  25  *
  26  * By doing this as an undefined instruction trap, we force a mode
  27  * switch from SVC to UND mode, allowing us to save full kernel state.
  28  *
  29  * We also define a KGDB_COMPILED_BREAK which can be used to compile
  30  * in breakpoints. This is important for things like sysrq-G and for
  31  * the initial breakpoint from trap_init().
  32  *
  33  * Note to ARM HW designers: Add real trap support like SH && PPC to
  34  * make our lives much much simpler. :)
  35  */
  36 #define BREAK_INSTR_SIZE        4
  37 #define GDB_BREAKINST           0xef9f0001
  38 #define KGDB_BREAKINST          0xe7ffdefe
  39 #define KGDB_COMPILED_BREAK     0xe7ffdeff
  40 #define CACHE_FLUSH_IS_SAFE     1
  41
  42 #ifndef __ASSEMBLY__
  43
  44 static inline void arch_kgdb_breakpoint(void)
  45 {
  46         asm(__inst_arm(0xe7ffdeff));
  47 }
  48
  49 extern void kgdb_handle_bus_error(void);
  50 extern int kgdb_fault_expected;
  51
  52 #endif /* !__ASSEMBLY__ */
  53
  54 /*
  55  * From Kevin Hilman:
  56  *
  57  * gdb is expecting the following registers layout.
  58  *
  59  * r0-r15: 1 long word each
  60  * f0-f7:  unused, 3 long words each !!
  61  * fps:    unused, 1 long word
  62  * cpsr:   1 long word
  63  *
  64  * Even though f0-f7 and fps are not used, they need to be
  65  * present in the registers sent for correct processing in
  66  * the host-side gdb.
  67  *
  68  * In particular, it is crucial that CPSR is in the right place,
  69  * otherwise gdb will not be able to correctly interpret stepping over
  70  * conditional branches.
  71  */
  72 #define _GP_REGS                16
  73 #define _FP_REGS                8
  74 #define _EXTRA_REGS             2
  75 #define GDB_MAX_REGS            (_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
  76 #define DBG_MAX_REG_NUM         (_GP_REGS + _FP_REGS + _EXTRA_REGS)
  77
  78 #define KGDB_MAX_NO_CPUS        1
  79 #define BUFMAX                  400
  80 #define NUMREGBYTES             (GDB_MAX_REGS << 2)
  81 #define NUMCRITREGBYTES         (32 << 2)
  82
  83 #define _R0                     0
  84 #define _R1                     1
  85 #define _R2                     2
  86 #define _R3                     3
  87 #define _R4                     4
  88 #define _R5                     5
  89 #define _R6                     6
  90 #define _R7                     7
  91 #define _R8                     8
  92 #define _R9                     9
  93 #define _R10                    10
  94 #define _FP                     11
  95 #define _IP                     12
  96 #define _SPT                    13
  97 #define _LR                     14
  98 #define _PC                     15
  99 #define _CPSR                   (GDB_MAX_REGS - 1)
 100
 101 /*
 102  * So that we can denote the end of a frame for tracing,
 103  * in the simple case:
 104  */
 105 #define CFI_END_FRAME(func)     __CFI_END_FRAME(_PC, _SPT, func)
 106
 107 #endif /* __ASM_KGDB_H__ */