1 // SPDX-License-Identifier: GPL-2.0
2 /* kgdb.c: KGDB support for 64-bit sparc.
3  *
4  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
5  */
6 
7 #include <linux/kgdb.h>
8 #include <linux/kdebug.h>
9 #include <linux/ftrace.h>
10 #include <linux/context_tracking.h>
11 
12 #include <asm/cacheflush.h>
13 #include <asm/kdebug.h>
14 #include <asm/ptrace.h>
15 #include <asm/irq.h>
16 
17 #include "kernel.h"
18 
pt_regs_to_gdb_regs(unsigned long * gdb_regs,struct pt_regs * regs)19 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
20 {
21 	struct reg_window *win;
22 	int i;
23 
24 	gdb_regs[GDB_G0] = 0;
25 	for (i = 0; i < 15; i++)
26 		gdb_regs[GDB_G1 + i] = regs->u_regs[UREG_G1 + i];
27 
28 	win = (struct reg_window *) (regs->u_regs[UREG_FP] + STACK_BIAS);
29 	for (i = 0; i < 8; i++)
30 		gdb_regs[GDB_L0 + i] = win->locals[i];
31 	for (i = 0; i < 8; i++)
32 		gdb_regs[GDB_I0 + i] = win->ins[i];
33 
34 	for (i = GDB_F0; i <= GDB_F62; i++)
35 		gdb_regs[i] = 0;
36 
37 	gdb_regs[GDB_PC] = regs->tpc;
38 	gdb_regs[GDB_NPC] = regs->tnpc;
39 	gdb_regs[GDB_STATE] = regs->tstate;
40 	gdb_regs[GDB_FSR] = 0;
41 	gdb_regs[GDB_FPRS] = 0;
42 	gdb_regs[GDB_Y] = regs->y;
43 }
44 
sleeping_thread_to_gdb_regs(unsigned long * gdb_regs,struct task_struct * p)45 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
46 {
47 	struct thread_info *t = task_thread_info(p);
48 	extern unsigned int switch_to_pc;
49 	extern unsigned int ret_from_fork;
50 	struct reg_window *win;
51 	unsigned long pc, cwp;
52 	int i;
53 
54 	for (i = GDB_G0; i < GDB_G6; i++)
55 		gdb_regs[i] = 0;
56 	gdb_regs[GDB_G6] = (unsigned long) t;
57 	gdb_regs[GDB_G7] = (unsigned long) p;
58 	for (i = GDB_O0; i < GDB_SP; i++)
59 		gdb_regs[i] = 0;
60 	gdb_regs[GDB_SP] = t->ksp;
61 	gdb_regs[GDB_O7] = 0;
62 
63 	win = (struct reg_window *) (t->ksp + STACK_BIAS);
64 	for (i = 0; i < 8; i++)
65 		gdb_regs[GDB_L0 + i] = win->locals[i];
66 	for (i = 0; i < 8; i++)
67 		gdb_regs[GDB_I0 + i] = win->ins[i];
68 
69 	for (i = GDB_F0; i <= GDB_F62; i++)
70 		gdb_regs[i] = 0;
71 
72 	if (t->new_child)
73 		pc = (unsigned long) &ret_from_fork;
74 	else
75 		pc = (unsigned long) &switch_to_pc;
76 
77 	gdb_regs[GDB_PC] = pc;
78 	gdb_regs[GDB_NPC] = pc + 4;
79 
80 	cwp = __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP];
81 
82 	gdb_regs[GDB_STATE] = (TSTATE_PRIV | TSTATE_IE | cwp);
83 	gdb_regs[GDB_FSR] = 0;
84 	gdb_regs[GDB_FPRS] = 0;
85 	gdb_regs[GDB_Y] = 0;
86 }
87 
gdb_regs_to_pt_regs(unsigned long * gdb_regs,struct pt_regs * regs)88 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
89 {
90 	struct reg_window *win;
91 	int i;
92 
93 	for (i = 0; i < 15; i++)
94 		regs->u_regs[UREG_G1 + i] = gdb_regs[GDB_G1 + i];
95 
96 	/* If the TSTATE register is changing, we have to preserve
97 	 * the CWP field, otherwise window save/restore explodes.
98 	 */
99 	if (regs->tstate != gdb_regs[GDB_STATE]) {
100 		unsigned long cwp = regs->tstate & TSTATE_CWP;
101 
102 		regs->tstate = (gdb_regs[GDB_STATE] & ~TSTATE_CWP) | cwp;
103 	}
104 
105 	regs->tpc = gdb_regs[GDB_PC];
106 	regs->tnpc = gdb_regs[GDB_NPC];
107 	regs->y = gdb_regs[GDB_Y];
108 
109 	win = (struct reg_window *) (regs->u_regs[UREG_FP] + STACK_BIAS);
110 	for (i = 0; i < 8; i++)
111 		win->locals[i] = gdb_regs[GDB_L0 + i];
112 	for (i = 0; i < 8; i++)
113 		win->ins[i] = gdb_regs[GDB_I0 + i];
114 }
115 
116 #ifdef CONFIG_SMP
smp_kgdb_capture_client(int irq,struct pt_regs * regs)117 void __irq_entry smp_kgdb_capture_client(int irq, struct pt_regs *regs)
118 {
119 	unsigned long flags;
120 
121 	__asm__ __volatile__("rdpr      %%pstate, %0\n\t"
122 			     "wrpr      %0, %1, %%pstate"
123 			     : "=r" (flags)
124 			     : "i" (PSTATE_IE));
125 
126 	flushw_all();
127 
128 	if (atomic_read(&kgdb_active) != -1)
129 		kgdb_nmicallback(raw_smp_processor_id(), regs);
130 
131 	__asm__ __volatile__("wrpr	%0, 0, %%pstate"
132 			     : : "r" (flags));
133 }
134 #endif
135 
kgdb_arch_handle_exception(int e_vector,int signo,int err_code,char * remcomInBuffer,char * remcomOutBuffer,struct pt_regs * linux_regs)136 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
137 			       char *remcomInBuffer, char *remcomOutBuffer,
138 			       struct pt_regs *linux_regs)
139 {
140 	unsigned long addr;
141 	char *ptr;
142 
143 	switch (remcomInBuffer[0]) {
144 	case 'c':
145 		/* try to read optional parameter, pc unchanged if no parm */
146 		ptr = &remcomInBuffer[1];
147 		if (kgdb_hex2long(&ptr, &addr)) {
148 			linux_regs->tpc = addr;
149 			linux_regs->tnpc = addr + 4;
150 		}
151 		fallthrough;
152 
153 	case 'D':
154 	case 'k':
155 		if (linux_regs->tpc == (unsigned long) arch_kgdb_breakpoint) {
156 			linux_regs->tpc = linux_regs->tnpc;
157 			linux_regs->tnpc += 4;
158 		}
159 		return 0;
160 	}
161 	return -1;
162 }
163 
kgdb_trap(unsigned long trap_level,struct pt_regs * regs)164 asmlinkage void kgdb_trap(unsigned long trap_level, struct pt_regs *regs)
165 {
166 	enum ctx_state prev_state = exception_enter();
167 	unsigned long flags;
168 
169 	if (user_mode(regs)) {
170 		bad_trap(regs, trap_level);
171 		goto out;
172 	}
173 
174 	flushw_all();
175 
176 	local_irq_save(flags);
177 	kgdb_handle_exception(0x172, SIGTRAP, 0, regs);
178 	local_irq_restore(flags);
179 out:
180 	exception_exit(prev_state);
181 }
182 
kgdb_arch_init(void)183 int kgdb_arch_init(void)
184 {
185 	return 0;
186 }
187 
kgdb_arch_exit(void)188 void kgdb_arch_exit(void)
189 {
190 }
191 
kgdb_arch_set_pc(struct pt_regs * regs,unsigned long ip)192 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
193 {
194 	regs->tpc = ip;
195 	regs->tnpc = regs->tpc + 4;
196 }
197 
198 const struct kgdb_arch arch_kgdb_ops = {
199 	/* Breakpoint instruction: ta 0x72 */
200 	.gdb_bpt_instr		= { 0x91, 0xd0, 0x20, 0x72 },
201 };
202