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__ */ 108