xref: /openbmc/qemu/target/arm/arch_dump.c (revision a9ded601) 
1 /* Support for writing ELF notes for ARM architectures
2  *
3  * Copyright (C) 2015 Red Hat Inc.
4  *
5  * Author: Andrew Jones <drjones@redhat.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program 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
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include "qemu/osdep.h"
22 #include "cpu.h"
23 #include "elf.h"
24 #include "sysemu/dump.h"
25 
26 /* struct user_pt_regs from arch/arm64/include/uapi/asm/ptrace.h */
27 struct aarch64_user_regs {
28     uint64_t regs[31];
29     uint64_t sp;
30     uint64_t pc;
31     uint64_t pstate;
32 } QEMU_PACKED;
33 
34 QEMU_BUILD_BUG_ON(sizeof(struct aarch64_user_regs) != 272);
35 
36 /* struct elf_prstatus from include/uapi/linux/elfcore.h */
37 struct aarch64_elf_prstatus {
38     char pad1[32]; /* 32 == offsetof(struct elf_prstatus, pr_pid) */
39     uint32_t pr_pid;
40     char pad2[76]; /* 76 == offsetof(struct elf_prstatus, pr_reg) -
41                             offsetof(struct elf_prstatus, pr_ppid) */
42     struct aarch64_user_regs pr_reg;
43     uint32_t pr_fpvalid;
44     char pad3[4];
45 } QEMU_PACKED;
46 
47 QEMU_BUILD_BUG_ON(sizeof(struct aarch64_elf_prstatus) != 392);
48 
49 /* struct user_fpsimd_state from arch/arm64/include/uapi/asm/ptrace.h
50  *
51  * While the vregs member of user_fpsimd_state is of type __uint128_t,
52  * QEMU uses an array of uint64_t, where the high half of the 128-bit
53  * value is always in the 2n+1'th index. Thus we also break the 128-
54  * bit values into two halves in this reproduction of user_fpsimd_state.
55  */
56 struct aarch64_user_vfp_state {
57     uint64_t vregs[64];
58     uint32_t fpsr;
59     uint32_t fpcr;
60     char pad[8];
61 } QEMU_PACKED;
62 
63 QEMU_BUILD_BUG_ON(sizeof(struct aarch64_user_vfp_state) != 528);
64 
65 struct aarch64_note {
66     Elf64_Nhdr hdr;
67     char name[8]; /* align_up(sizeof("CORE"), 4) */
68     union {
69         struct aarch64_elf_prstatus prstatus;
70         struct aarch64_user_vfp_state vfp;
71     };
72 } QEMU_PACKED;
73 
74 #define AARCH64_NOTE_HEADER_SIZE offsetof(struct aarch64_note, prstatus)
75 #define AARCH64_PRSTATUS_NOTE_SIZE \
76             (AARCH64_NOTE_HEADER_SIZE + sizeof(struct aarch64_elf_prstatus))
77 #define AARCH64_PRFPREG_NOTE_SIZE \
78             (AARCH64_NOTE_HEADER_SIZE + sizeof(struct aarch64_user_vfp_state))
79 
80 static void aarch64_note_init(struct aarch64_note *note, DumpState *s,
81                               const char *name, Elf64_Word namesz,
82                               Elf64_Word type, Elf64_Word descsz)
83 {
84     memset(note, 0, sizeof(*note));
85 
86     note->hdr.n_namesz = cpu_to_dump32(s, namesz);
87     note->hdr.n_descsz = cpu_to_dump32(s, descsz);
88     note->hdr.n_type = cpu_to_dump32(s, type);
89 
90     memcpy(note->name, name, namesz);
91 }
92 
93 static int aarch64_write_elf64_prfpreg(WriteCoreDumpFunction f,
94                                        CPUARMState *env, int cpuid,
95                                        DumpState *s)
96 {
97     struct aarch64_note note;
98     int ret, i;
99 
100     aarch64_note_init(&note, s, "CORE", 5, NT_PRFPREG, sizeof(note.vfp));
101 
102     for (i = 0; i < 64; ++i) {
103         note.vfp.vregs[i] = cpu_to_dump64(s, float64_val(env->vfp.regs[i]));
104     }
105 
106     if (s->dump_info.d_endian == ELFDATA2MSB) {
107         /* For AArch64 we must always swap the vfp.regs's 2n and 2n+1
108          * entries when generating BE notes, because even big endian
109          * hosts use 2n+1 for the high half.
110          */
111         for (i = 0; i < 32; ++i) {
112             uint64_t tmp = note.vfp.vregs[2*i];
113             note.vfp.vregs[2*i] = note.vfp.vregs[2*i+1];
114             note.vfp.vregs[2*i+1] = tmp;
115         }
116     }
117 
118     note.vfp.fpsr = cpu_to_dump32(s, vfp_get_fpsr(env));
119     note.vfp.fpcr = cpu_to_dump32(s, vfp_get_fpcr(env));
120 
121     ret = f(&note, AARCH64_PRFPREG_NOTE_SIZE, s);
122     if (ret < 0) {
123         return -1;
124     }
125 
126     return 0;
127 }
128 
129 int arm_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
130                              int cpuid, void *opaque)
131 {
132     struct aarch64_note note;
133     CPUARMState *env = &ARM_CPU(cs)->env;
134     DumpState *s = opaque;
135     uint64_t pstate, sp;
136     int ret, i;
137 
138     aarch64_note_init(&note, s, "CORE", 5, NT_PRSTATUS, sizeof(note.prstatus));
139 
140     note.prstatus.pr_pid = cpu_to_dump32(s, cpuid);
141     note.prstatus.pr_fpvalid = cpu_to_dump32(s, 1);
142 
143     if (!is_a64(env)) {
144         aarch64_sync_32_to_64(env);
145         pstate = cpsr_read(env);
146         sp = 0;
147     } else {
148         pstate = pstate_read(env);
149         sp = env->xregs[31];
150     }
151 
152     for (i = 0; i < 31; ++i) {
153         note.prstatus.pr_reg.regs[i] = cpu_to_dump64(s, env->xregs[i]);
154     }
155     note.prstatus.pr_reg.sp = cpu_to_dump64(s, sp);
156     note.prstatus.pr_reg.pc = cpu_to_dump64(s, env->pc);
157     note.prstatus.pr_reg.pstate = cpu_to_dump64(s, pstate);
158 
159     ret = f(&note, AARCH64_PRSTATUS_NOTE_SIZE, s);
160     if (ret < 0) {
161         return -1;
162     }
163 
164     return aarch64_write_elf64_prfpreg(f, env, cpuid, s);
165 }
166 
167 /* struct pt_regs from arch/arm/include/asm/ptrace.h */
168 struct arm_user_regs {
169     uint32_t regs[17];
170     char pad[4];
171 } QEMU_PACKED;
172 
173 QEMU_BUILD_BUG_ON(sizeof(struct arm_user_regs) != 72);
174 
175 /* struct elf_prstatus from include/uapi/linux/elfcore.h */
176 struct arm_elf_prstatus {
177     char pad1[24]; /* 24 == offsetof(struct elf_prstatus, pr_pid) */
178     uint32_t pr_pid;
179     char pad2[44]; /* 44 == offsetof(struct elf_prstatus, pr_reg) -
180                             offsetof(struct elf_prstatus, pr_ppid) */
181     struct arm_user_regs pr_reg;
182     uint32_t pr_fpvalid;
183 } QEMU_PACKED arm_elf_prstatus;
184 
185 QEMU_BUILD_BUG_ON(sizeof(struct arm_elf_prstatus) != 148);
186 
187 /* struct user_vfp from arch/arm/include/asm/user.h */
188 struct arm_user_vfp_state {
189     uint64_t vregs[32];
190     uint32_t fpscr;
191 } QEMU_PACKED;
192 
193 QEMU_BUILD_BUG_ON(sizeof(struct arm_user_vfp_state) != 260);
194 
195 struct arm_note {
196     Elf32_Nhdr hdr;
197     char name[8]; /* align_up(sizeof("LINUX"), 4) */
198     union {
199         struct arm_elf_prstatus prstatus;
200         struct arm_user_vfp_state vfp;
201     };
202 } QEMU_PACKED;
203 
204 #define ARM_NOTE_HEADER_SIZE offsetof(struct arm_note, prstatus)
205 #define ARM_PRSTATUS_NOTE_SIZE \
206             (ARM_NOTE_HEADER_SIZE + sizeof(struct arm_elf_prstatus))
207 #define ARM_VFP_NOTE_SIZE \
208             (ARM_NOTE_HEADER_SIZE + sizeof(struct arm_user_vfp_state))
209 
210 static void arm_note_init(struct arm_note *note, DumpState *s,
211                           const char *name, Elf32_Word namesz,
212                           Elf32_Word type, Elf32_Word descsz)
213 {
214     memset(note, 0, sizeof(*note));
215 
216     note->hdr.n_namesz = cpu_to_dump32(s, namesz);
217     note->hdr.n_descsz = cpu_to_dump32(s, descsz);
218     note->hdr.n_type = cpu_to_dump32(s, type);
219 
220     memcpy(note->name, name, namesz);
221 }
222 
223 static int arm_write_elf32_vfp(WriteCoreDumpFunction f, CPUARMState *env,
224                                int cpuid, DumpState *s)
225 {
226     struct arm_note note;
227     int ret, i;
228 
229     arm_note_init(&note, s, "LINUX", 6, NT_ARM_VFP, sizeof(note.vfp));
230 
231     for (i = 0; i < 32; ++i) {
232         note.vfp.vregs[i] = cpu_to_dump64(s, float64_val(env->vfp.regs[i]));
233     }
234 
235     note.vfp.fpscr = cpu_to_dump32(s, vfp_get_fpscr(env));
236 
237     ret = f(&note, ARM_VFP_NOTE_SIZE, s);
238     if (ret < 0) {
239         return -1;
240     }
241 
242     return 0;
243 }
244 
245 int arm_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
246                              int cpuid, void *opaque)
247 {
248     struct arm_note note;
249     CPUARMState *env = &ARM_CPU(cs)->env;
250     DumpState *s = opaque;
251     int ret, i, fpvalid = !!arm_feature(env, ARM_FEATURE_VFP);
252 
253     arm_note_init(&note, s, "CORE", 5, NT_PRSTATUS, sizeof(note.prstatus));
254 
255     note.prstatus.pr_pid = cpu_to_dump32(s, cpuid);
256     note.prstatus.pr_fpvalid = cpu_to_dump32(s, fpvalid);
257 
258     for (i = 0; i < 16; ++i) {
259         note.prstatus.pr_reg.regs[i] = cpu_to_dump32(s, env->regs[i]);
260     }
261     note.prstatus.pr_reg.regs[16] = cpu_to_dump32(s, cpsr_read(env));
262 
263     ret = f(&note, ARM_PRSTATUS_NOTE_SIZE, s);
264     if (ret < 0) {
265         return -1;
266     } else if (fpvalid) {
267         return arm_write_elf32_vfp(f, env, cpuid, s);
268     }
269 
270     return 0;
271 }
272 
273 int cpu_get_dump_info(ArchDumpInfo *info,
274                       const GuestPhysBlockList *guest_phys_blocks)
275 {
276     ARMCPU *cpu = ARM_CPU(first_cpu);
277     CPUARMState *env = &cpu->env;
278     GuestPhysBlock *block;
279     hwaddr lowest_addr = ULLONG_MAX;
280 
281     /* Take a best guess at the phys_base. If we get it wrong then crash
282      * will need '--machdep phys_offset=<phys-offset>' added to its command
283      * line, which isn't any worse than assuming we can use zero, but being
284      * wrong. This is the same algorithm the crash utility uses when
285      * attempting to guess as it loads non-dumpfile formatted files.
286      */
287     QTAILQ_FOREACH(block, &guest_phys_blocks->head, next) {
288         if (block->target_start < lowest_addr) {
289             lowest_addr = block->target_start;
290         }
291     }
292 
293     if (arm_feature(env, ARM_FEATURE_AARCH64)) {
294         info->d_machine = EM_AARCH64;
295         info->d_class = ELFCLASS64;
296         info->page_size = (1 << 16); /* aarch64 max pagesize */
297         if (lowest_addr != ULLONG_MAX) {
298             info->phys_base = lowest_addr;
299         }
300     } else {
301         info->d_machine = EM_ARM;
302         info->d_class = ELFCLASS32;
303         info->page_size = (1 << 12);
304         if (lowest_addr < UINT_MAX) {
305             info->phys_base = lowest_addr;
306         }
307     }
308 
309     /* We assume the relevant endianness is that of EL1; this is right
310      * for kernels, but might give the wrong answer if you're trying to
311      * dump a hypervisor that happens to be running an opposite-endian
312      * kernel.
313      */
314     info->d_endian = (env->cp15.sctlr_el[1] & SCTLR_EE) != 0
315                      ? ELFDATA2MSB : ELFDATA2LSB;
316 
317     return 0;
318 }
319 
320 ssize_t cpu_get_note_size(int class, int machine, int nr_cpus)
321 {
322     ARMCPU *cpu = ARM_CPU(first_cpu);
323     CPUARMState *env = &cpu->env;
324     size_t note_size;
325 
326     if (class == ELFCLASS64) {
327         note_size = AARCH64_PRSTATUS_NOTE_SIZE;
328         note_size += AARCH64_PRFPREG_NOTE_SIZE;
329     } else {
330         note_size = ARM_PRSTATUS_NOTE_SIZE;
331         if (arm_feature(env, ARM_FEATURE_VFP)) {
332             note_size += ARM_VFP_NOTE_SIZE;
333         }
334     }
335 
336     return note_size * nr_cpus;
337 }
338