1 /*
2 * CPU watchpoints
3 *
4 * Copyright (c) 2003 Fabrice Bellard
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "qemu/main-loop.h"
22 #include "exec/breakpoint.h"
23 #include "exec/cpu-interrupt.h"
24 #include "exec/page-protection.h"
25 #include "exec/translation-block.h"
26 #include "system/tcg.h"
27 #include "system/replay.h"
28 #include "accel/tcg/cpu-ops.h"
29 #include "hw/core/cpu.h"
30 #include "internal-common.h"
31
32 /*
33 * Return true if this watchpoint address matches the specified
34 * access (ie the address range covered by the watchpoint overlaps
35 * partially or completely with the address range covered by the
36 * access).
37 */
watchpoint_address_matches(CPUWatchpoint * wp,vaddr addr,vaddr len)38 static inline bool watchpoint_address_matches(CPUWatchpoint *wp,
39 vaddr addr, vaddr len)
40 {
41 /*
42 * We know the lengths are non-zero, but a little caution is
43 * required to avoid errors in the case where the range ends
44 * exactly at the top of the address space and so addr + len
45 * wraps round to zero.
46 */
47 vaddr wpend = wp->vaddr + wp->len - 1;
48 vaddr addrend = addr + len - 1;
49
50 return !(addr > wpend || wp->vaddr > addrend);
51 }
52
53 /* Return flags for watchpoints that match addr + prot. */
cpu_watchpoint_address_matches(CPUState * cpu,vaddr addr,vaddr len)54 int cpu_watchpoint_address_matches(CPUState *cpu, vaddr addr, vaddr len)
55 {
56 CPUWatchpoint *wp;
57 int ret = 0;
58
59 QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
60 if (watchpoint_address_matches(wp, addr, len)) {
61 ret |= wp->flags;
62 }
63 }
64 return ret;
65 }
66
67 /* Generate a debug exception if a watchpoint has been hit. */
cpu_check_watchpoint(CPUState * cpu,vaddr addr,vaddr len,MemTxAttrs attrs,int flags,uintptr_t ra)68 void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
69 MemTxAttrs attrs, int flags, uintptr_t ra)
70 {
71 CPUWatchpoint *wp;
72
73 assert(tcg_enabled());
74 if (cpu->watchpoint_hit) {
75 /*
76 * We re-entered the check after replacing the TB.
77 * Now raise the debug interrupt so that it will
78 * trigger after the current instruction.
79 */
80 bql_lock();
81 cpu_interrupt(cpu, CPU_INTERRUPT_DEBUG);
82 bql_unlock();
83 return;
84 }
85
86 if (cpu->cc->tcg_ops->adjust_watchpoint_address) {
87 /* this is currently used only by ARM BE32 */
88 addr = cpu->cc->tcg_ops->adjust_watchpoint_address(cpu, addr, len);
89 }
90
91 assert((flags & ~BP_MEM_ACCESS) == 0);
92 QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
93 int hit_flags = wp->flags & flags;
94
95 if (hit_flags && watchpoint_address_matches(wp, addr, len)) {
96 if (replay_running_debug()) {
97 /*
98 * replay_breakpoint reads icount.
99 * Force recompile to succeed, because icount may
100 * be read only at the end of the block.
101 */
102 if (!cpu->neg.can_do_io) {
103 /* Force execution of one insn next time. */
104 cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(cpu);
105 cpu_loop_exit_restore(cpu, ra);
106 }
107 /*
108 * Don't process the watchpoints when we are
109 * in a reverse debugging operation.
110 */
111 replay_breakpoint();
112 return;
113 }
114
115 wp->flags |= hit_flags << BP_HIT_SHIFT;
116 wp->hitaddr = MAX(addr, wp->vaddr);
117 wp->hitattrs = attrs;
118
119 if (wp->flags & BP_CPU
120 && cpu->cc->tcg_ops->debug_check_watchpoint
121 && !cpu->cc->tcg_ops->debug_check_watchpoint(cpu, wp)) {
122 wp->flags &= ~BP_WATCHPOINT_HIT;
123 continue;
124 }
125 cpu->watchpoint_hit = wp;
126
127 /* This call also restores vCPU state */
128 tb_check_watchpoint(cpu, ra);
129 if (wp->flags & BP_STOP_BEFORE_ACCESS) {
130 cpu->exception_index = EXCP_DEBUG;
131 cpu_loop_exit(cpu);
132 } else {
133 /* Force execution of one insn next time. */
134 cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(cpu);
135 cpu_loop_exit_noexc(cpu);
136 }
137 } else {
138 wp->flags &= ~BP_WATCHPOINT_HIT;
139 }
140 }
141 }
142