1/*
  2 * kgdb support for ARC
  3 *
  4 * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10
 11#include <linux/kgdb.h>
 12#include <linux/sched.h>
 13#include <asm/disasm.h>
 14#include <asm/cacheflush.h>
 15
 16static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs,
 17			struct callee_regs *cregs)
 18{
 19	int regno;
 20
 21	for (regno = 0; regno <= 26; regno++)
 22		gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs);
 23
 24	for (regno = 27; regno < GDB_MAX_REGS; regno++)
 25		gdb_regs[regno] = 0;
 26
 27	gdb_regs[_FP]		= kernel_regs->fp;
 28	gdb_regs[__SP]		= kernel_regs->sp;
 29	gdb_regs[_BLINK]	= kernel_regs->blink;
 30	gdb_regs[_RET]		= kernel_regs->ret;
 31	gdb_regs[_STATUS32]	= kernel_regs->status32;
 32	gdb_regs[_LP_COUNT]	= kernel_regs->lp_count;
 33	gdb_regs[_LP_END]	= kernel_regs->lp_end;
 34	gdb_regs[_LP_START]	= kernel_regs->lp_start;
 35	gdb_regs[_BTA]		= kernel_regs->bta;
 36	gdb_regs[_STOP_PC]	= kernel_regs->ret;
 37}
 38
 39static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs,
 40			struct callee_regs *cregs)
 41{
 42	int regno;
 43
 44	for (regno = 0; regno <= 26; regno++)
 45		set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs);
 46
 47	kernel_regs->fp		= gdb_regs[_FP];
 48	kernel_regs->sp		= gdb_regs[__SP];
 49	kernel_regs->blink	= gdb_regs[_BLINK];
 50	kernel_regs->ret	= gdb_regs[_RET];
 51	kernel_regs->status32	= gdb_regs[_STATUS32];
 52	kernel_regs->lp_count	= gdb_regs[_LP_COUNT];
 53	kernel_regs->lp_end	= gdb_regs[_LP_END];
 54	kernel_regs->lp_start	= gdb_regs[_LP_START];
 55	kernel_regs->bta	= gdb_regs[_BTA];
 56}
 57
 58
 59void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
 60{
 61	to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *)
 62		current->thread.callee_reg);
 63}
 64
 65void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
 66{
 67	from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *)
 68		current->thread.callee_reg);
 69}
 70
 71void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
 72				 struct task_struct *task)
 73{
 74	if (task)
 75		to_gdb_regs(gdb_regs, task_pt_regs(task),
 76			(struct callee_regs *) task->thread.callee_reg);
 77}
 78
 79struct single_step_data_t {
 80	uint16_t opcode[2];
 81	unsigned long address[2];
 82	int is_branch;
 83	int armed;
 84} single_step_data;
 85
 86static void undo_single_step(struct pt_regs *regs)
 87{
 88	if (single_step_data.armed) {
 89		int i;
 90
 91		for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) {
 92			memcpy((void *) single_step_data.address[i],
 93				&single_step_data.opcode[i],
 94				BREAK_INSTR_SIZE);
 95
 96			flush_icache_range(single_step_data.address[i],
 97				single_step_data.address[i] +
 98				BREAK_INSTR_SIZE);
 99		}
100		single_step_data.armed = 0;
101	}
102}
103
104static void place_trap(unsigned long address, void *save)
105{
106	memcpy(save, (void *) address, BREAK_INSTR_SIZE);
107	memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr,
108		BREAK_INSTR_SIZE);
109	flush_icache_range(address, address + BREAK_INSTR_SIZE);
110}
111
112static void do_single_step(struct pt_regs *regs)
113{
114	single_step_data.is_branch = disasm_next_pc((unsigned long)
115		regs->ret, regs, (struct callee_regs *)
116		current->thread.callee_reg,
117		&single_step_data.address[0],
118		&single_step_data.address[1]);
119
120	place_trap(single_step_data.address[0], &single_step_data.opcode[0]);
121
122	if (single_step_data.is_branch) {
123		place_trap(single_step_data.address[1],
124			&single_step_data.opcode[1]);
125	}
126
127	single_step_data.armed++;
128}
129
130int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
131			       char *remcomInBuffer, char *remcomOutBuffer,
132			       struct pt_regs *regs)
133{
134	unsigned long addr;
135	char *ptr;
136
137	undo_single_step(regs);
138
139	switch (remcomInBuffer[0]) {
140	case 's':
141	case 'c':
142		ptr = &remcomInBuffer[1];
143		if (kgdb_hex2long(&ptr, &addr))
144			regs->ret = addr;
145
146	case 'D':
147	case 'k':
148		atomic_set(&kgdb_cpu_doing_single_step, -1);
149
150		if (remcomInBuffer[0] == 's') {
151			do_single_step(regs);
152			atomic_set(&kgdb_cpu_doing_single_step,
153				   smp_processor_id());
154		}
155
156		return 0;
157	}
158	return -1;
159}
160
161int kgdb_arch_init(void)
162{
163	single_step_data.armed = 0;
164	return 0;
165}
166
167void kgdb_trap(struct pt_regs *regs)
168{
169	/* trap_s 3 is used for breakpoints that overwrite existing
170	 * instructions, while trap_s 4 is used for compiled breakpoints.
171	 *
172	 * with trap_s 3 breakpoints the original instruction needs to be
173	 * restored and continuation needs to start at the location of the
174	 * breakpoint.
175	 *
176	 * with trap_s 4 (compiled) breakpoints, continuation needs to
177	 * start after the breakpoint.
178	 */
179	if (regs->ecr_param == 3)
180		instruction_pointer(regs) -= BREAK_INSTR_SIZE;
181
182	kgdb_handle_exception(1, SIGTRAP, 0, regs);
183}
184
185void kgdb_arch_exit(void)
186{
187}
188
189void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
190{
191	instruction_pointer(regs) = ip;
192}
193
194static void kgdb_call_nmi_hook(void *ignored)
195{
196	kgdb_nmicallback(raw_smp_processor_id(), NULL);
197}
198
199void kgdb_roundup_cpus(unsigned long flags)
200{
201	local_irq_enable();
202	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
203	local_irq_disable();
204}
205
206struct kgdb_arch arch_kgdb_ops = {
207	/* breakpoint instruction: TRAP_S 0x3 */
208#ifdef CONFIG_CPU_BIG_ENDIAN
209	.gdb_bpt_instr		= {0x78, 0x7e},
210#else
211	.gdb_bpt_instr		= {0x7e, 0x78},
212#endif
213};