include/asm/kgdb.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * ARM KGDB support
0004  *
0005  * Author: Deepak Saxena <dsaxena@mvista.com>
0006  *
0007  * Copyright (C) 2002 MontaVista Software Inc.
0008  *
0009  */
0010
0011 #ifndef __ARM_KGDB_H__
0012 #define __ARM_KGDB_H__
0013
0014 #include <linux/ptrace.h>
0015 #include <asm/opcodes.h>
0016
0017 /*
0018  * GDB assumes that we're a user process being debugged, so
0019  * it will send us an SWI command to write into memory as the
0020  * debug trap. When an SWI occurs, the next instruction addr is
0021  * placed into R14_svc before jumping to the vector trap.
0022  * This doesn't work for kernel debugging as we are already in SVC
0023  * we would loose the kernel's LR, which is a bad thing. This
0024  * is  bad thing.
0025  *
0026  * By doing this as an undefined instruction trap, we force a mode
0027  * switch from SVC to UND mode, allowing us to save full kernel state.
0028  *
0029  * We also define a KGDB_COMPILED_BREAK which can be used to compile
0030  * in breakpoints. This is important for things like sysrq-G and for
0031  * the initial breakpoint from trap_init().
0032  *
0033  * Note to ARM HW designers: Add real trap support like SH && PPC to
0034  * make our lives much much simpler. :)
0035  */
0036 #define BREAK_INSTR_SIZE    4
0037 #define GDB_BREAKINST       0xef9f0001
0038 #define KGDB_BREAKINST      0xe7ffdefe
0039 #define KGDB_COMPILED_BREAK 0xe7ffdeff
0040 #define CACHE_FLUSH_IS_SAFE 1
0041
0042 #ifndef __ASSEMBLY__
0043
0044 static inline void arch_kgdb_breakpoint(void)
0045 {
0046     asm(__inst_arm(0xe7ffdeff));
0047 }
0048
0049 extern void kgdb_handle_bus_error(void);
0050 extern int kgdb_fault_expected;
0051
0052 #endif /* !__ASSEMBLY__ */
0053
0054 /*
0055  * From Kevin Hilman:
0056  *
0057  * gdb is expecting the following registers layout.
0058  *
0059  * r0-r15: 1 long word each
0060  * f0-f7:  unused, 3 long words each !!
0061  * fps:    unused, 1 long word
0062  * cpsr:   1 long word
0063  *
0064  * Even though f0-f7 and fps are not used, they need to be
0065  * present in the registers sent for correct processing in
0066  * the host-side gdb.
0067  *
0068  * In particular, it is crucial that CPSR is in the right place,
0069  * otherwise gdb will not be able to correctly interpret stepping over
0070  * conditional branches.
0071  */
0072 #define _GP_REGS        16
0073 #define _FP_REGS        8
0074 #define _EXTRA_REGS     2
0075 #define GDB_MAX_REGS        (_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
0076 #define DBG_MAX_REG_NUM     (_GP_REGS + _FP_REGS + _EXTRA_REGS)
0077
0078 #define KGDB_MAX_NO_CPUS    1
0079 #define BUFMAX          400
0080 #define NUMREGBYTES     (GDB_MAX_REGS << 2)
0081 #define NUMCRITREGBYTES     (32 << 2)
0082
0083 #define _R0         0
0084 #define _R1         1
0085 #define _R2         2
0086 #define _R3         3
0087 #define _R4         4
0088 #define _R5         5
0089 #define _R6         6
0090 #define _R7         7
0091 #define _R8         8
0092 #define _R9         9
0093 #define _R10            10
0094 #define _FP         11
0095 #define _IP         12
0096 #define _SPT            13
0097 #define _LR         14
0098 #define _PC         15
0099 #define _CPSR           (GDB_MAX_REGS - 1)
0100
0101 /*
0102  * So that we can denote the end of a frame for tracing,
0103  * in the simple case:
0104  */
0105 #define CFI_END_FRAME(func) __CFI_END_FRAME(_PC, _SPT, func)
0106
0107 #endif /* __ASM_KGDB_H__ */