xref: /openbmc/qemu/target/arm/gdbstub.c (revision dc5bd18f)
1 /*
2  * ARM gdb server stub
3  *
4  * Copyright (c) 2003-2005 Fabrice Bellard
5  * Copyright (c) 2013 SUSE LINUX Products GmbH
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2 of the License, or (at your option) any later version.
11  *
12  * This library is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
19  */
20 #include "qemu/osdep.h"
21 #include "qemu-common.h"
22 #include "cpu.h"
23 #include "exec/gdbstub.h"
24 
25 /* Old gdb always expect FPA registers.  Newer (xml-aware) gdb only expect
26    whatever the target description contains.  Due to a historical mishap
27    the FPA registers appear in between core integer regs and the CPSR.
28    We hack round this by giving the FPA regs zero size when talking to a
29    newer gdb.  */
30 
31 int arm_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
32 {
33     ARMCPU *cpu = ARM_CPU(cs);
34     CPUARMState *env = &cpu->env;
35 
36     if (n < 16) {
37         /* Core integer register.  */
38         return gdb_get_reg32(mem_buf, env->regs[n]);
39     }
40     if (n < 24) {
41         /* FPA registers.  */
42         if (gdb_has_xml) {
43             return 0;
44         }
45         memset(mem_buf, 0, 12);
46         return 12;
47     }
48     switch (n) {
49     case 24:
50         /* FPA status register.  */
51         if (gdb_has_xml) {
52             return 0;
53         }
54         return gdb_get_reg32(mem_buf, 0);
55     case 25:
56         /* CPSR */
57         return gdb_get_reg32(mem_buf, cpsr_read(env));
58     }
59     /* Unknown register.  */
60     return 0;
61 }
62 
63 int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
64 {
65     ARMCPU *cpu = ARM_CPU(cs);
66     CPUARMState *env = &cpu->env;
67     uint32_t tmp;
68 
69     tmp = ldl_p(mem_buf);
70 
71     /* Mask out low bit of PC to workaround gdb bugs.  This will probably
72        cause problems if we ever implement the Jazelle DBX extensions.  */
73     if (n == 15) {
74         tmp &= ~1;
75     }
76 
77     if (n < 16) {
78         /* Core integer register.  */
79         env->regs[n] = tmp;
80         return 4;
81     }
82     if (n < 24) { /* 16-23 */
83         /* FPA registers (ignored).  */
84         if (gdb_has_xml) {
85             return 0;
86         }
87         return 12;
88     }
89     switch (n) {
90     case 24:
91         /* FPA status register (ignored).  */
92         if (gdb_has_xml) {
93             return 0;
94         }
95         return 4;
96     case 25:
97         /* CPSR */
98         cpsr_write(env, tmp, 0xffffffff, CPSRWriteByGDBStub);
99         return 4;
100     }
101     /* Unknown register.  */
102     return 0;
103 }
104