machine.c revision f2eae5a860ebdf0dd47669c9bf58b8824b57728c 
1/* system/debuggerd/debuggerd.c
2**
3** Copyright 2006, The Android Open Source Project
4**
5** Licensed under the Apache License, Version 2.0 (the "License");
6** you may not use this file except in compliance with the License.
7** You may obtain a copy of the License at
8**
9**     http://www.apache.org/licenses/LICENSE-2.0
10**
11** Unless required by applicable law or agreed to in writing, software
12** distributed under the License is distributed on an "AS IS" BASIS,
13** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14** See the License for the specific language governing permissions and
15** limitations under the License.
16*/
17
18#include <stdio.h>
19#include <errno.h>
20#include <signal.h>
21#include <pthread.h>
22#include <fcntl.h>
23#include <sys/types.h>
24#include <dirent.h>
25
26#include <sys/ptrace.h>
27#include <sys/wait.h>
28#include <sys/exec_elf.h>
29#include <sys/stat.h>
30
31#include <cutils/sockets.h>
32#include <cutils/properties.h>
33
34#include <linux/input.h>
35#include <linux/user.h>
36
37#include "utility.h"
38
39/* enable to dump memory pointed to by every register */
40#define DUMP_MEM_FOR_ALL_REGS 0
41
42#ifdef WITH_VFP
43#ifdef WITH_VFP_D32
44#define NUM_VFP_REGS 32
45#else
46#define NUM_VFP_REGS 16
47#endif
48#endif
49
50/* Main entry point to get the backtrace from the crashing process */
51extern int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map,
52                                        unsigned int sp_list[],
53                                        int *frame0_pc_sane,
54                                        bool at_fault);
55
56/*
57 * If this isn't clearly a null pointer dereference, dump the
58 * /proc/maps entries near the fault address.
59 */
60static void show_nearby_maps(int tfd, int pid, mapinfo *map)
61{
62    siginfo_t si;
63
64    memset(&si, 0, sizeof(si));
65    if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si)) {
66        _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
67        return;
68    }
69    if (!signal_has_address(si.si_signo))
70        return;
71
72    uintptr_t addr = (uintptr_t) si.si_addr;
73    addr &= ~0xfff;     /* round to 4K page boundary */
74    if (addr == 0)      /* null-pointer deref */
75        return;
76
77    _LOG(tfd, false, "\nmemory map around addr %08x:\n", si.si_addr);
78
79    /*
80     * Search for a match, or for a hole where the match would be.  The list
81     * is backward from the file content, so it starts at high addresses.
82     */
83    bool found = false;
84    mapinfo *next = NULL;
85    mapinfo *prev = NULL;
86    while (map != NULL) {
87        if (addr >= map->start && addr < map->end) {
88            found = true;
89            next = map->next;
90            break;
91        } else if (addr >= map->end) {
92            /* map would be between "prev" and this entry */
93            next = map;
94            map = NULL;
95            break;
96        }
97
98        prev = map;
99        map = map->next;
100    }
101
102    /*
103     * Show "next" then "match" then "prev" so that the addresses appear in
104     * ascending order (like /proc/pid/maps).
105     */
106    if (next != NULL) {
107        _LOG(tfd, false, "%08x-%08x %s\n", next->start, next->end, next->name);
108    } else {
109        _LOG(tfd, false, "(no map below)\n");
110    }
111    if (map != NULL) {
112        _LOG(tfd, false, "%08x-%08x %s\n", map->start, map->end, map->name);
113    } else {
114        _LOG(tfd, false, "(no map for address)\n");
115    }
116    if (prev != NULL) {
117        _LOG(tfd, false, "%08x-%08x %s\n", prev->start, prev->end, prev->name);
118    } else {
119        _LOG(tfd, false, "(no map above)\n");
120    }
121}
122
123/*
124 * Dumps a few bytes of memory, starting a bit before and ending a bit
125 * after the specified address.
126 */
127static void dump_memory(int tfd, int pid, uintptr_t addr,
128    bool only_in_tombstone)
129{
130    char code_buffer[64];       /* actual 8+1+((8+1)*4) + 1 == 45 */
131    char ascii_buffer[32];      /* actual 16 + 1 == 17 */
132    uintptr_t p, end;
133
134    p = addr & ~3;
135    p -= 32;
136    if (p > addr) {
137        /* catch underflow */
138        p = 0;
139    }
140    end = p + 80;
141    /* catch overflow; 'end - p' has to be multiples of 16 */
142    while (end < p)
143        end -= 16;
144
145    /* Dump the code around PC as:
146     *  addr     contents                             ascii
147     *  00008d34 ef000000 e8bd0090 e1b00000 512fff1e  ............../Q
148     *  00008d44 ea00b1f9 e92d0090 e3a070fc ef000000  ......-..p......
149     */
150    while (p < end) {
151        char* asc_out = ascii_buffer;
152
153        sprintf(code_buffer, "%08x ", p);
154
155        int i;
156        for (i = 0; i < 4; i++) {
157            /*
158             * If we see (data == -1 && errno != 0), we know that the ptrace
159             * call failed, probably because we're dumping memory in an
160             * unmapped or inaccessible page.  I don't know if there's
161             * value in making that explicit in the output -- it likely
162             * just complicates parsing and clarifies nothing for the
163             * enlightened reader.
164             */
165            long data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
166            sprintf(code_buffer + strlen(code_buffer), "%08lx ", data);
167
168            int j;
169            for (j = 0; j < 4; j++) {
170                /*
171                 * Our isprint() allows high-ASCII characters that display
172                 * differently (often badly) in different viewers, so we
173                 * just use a simpler test.
174                 */
175                char val = (data >> (j*8)) & 0xff;
176                if (val >= 0x20 && val < 0x7f) {
177                    *asc_out++ = val;
178                } else {
179                    *asc_out++ = '.';
180                }
181            }
182            p += 4;
183        }
184        *asc_out = '\0';
185        _LOG(tfd, only_in_tombstone, "%s %s\n", code_buffer, ascii_buffer);
186    }
187
188}
189
190void dump_stack_and_code(int tfd, int pid, mapinfo *map,
191                         int unwind_depth, unsigned int sp_list[],
192                         bool at_fault)
193{
194    struct pt_regs r;
195    int sp_depth;
196    bool only_in_tombstone = !at_fault;
197
198    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return;
199
200    if (DUMP_MEM_FOR_ALL_REGS && at_fault) {
201        /*
202         * If configured to do so, dump memory around *all* registers
203         * for the crashing thread.
204         *
205         * TODO: remove duplicates.
206         */
207        static const char REG_NAMES[] = "R0R1R2R3R4R5R6R7R8R9SLFPIPSPLRPC";
208
209        int reg;
210        for (reg = 0; reg < 16; reg++) {
211            /* this may not be a valid way to access, but it'll do for now */
212            uintptr_t addr = r.uregs[reg];
213
214            /*
215             * Don't bother if it looks like a small int or ~= null, or if
216             * it's in the kernel area.
217             */
218            if (addr < 4096 || addr >= 0xc0000000) {
219                continue;
220            }
221
222            _LOG(tfd, only_in_tombstone, "\nmem near %.2s:\n",
223                &REG_NAMES[reg*2]);
224            dump_memory(tfd, pid, addr, false);
225        }
226    } else {
227        unsigned int pc, lr;
228        pc = r.ARM_pc;
229        lr = r.ARM_lr;
230
231        _LOG(tfd, only_in_tombstone, "\ncode around pc:\n");
232        dump_memory(tfd, pid, (uintptr_t) pc, only_in_tombstone);
233
234        if (lr != pc) {
235            _LOG(tfd, only_in_tombstone, "\ncode around lr:\n");
236            dump_memory(tfd, pid, (uintptr_t) lr, only_in_tombstone);
237        }
238    }
239
240    show_nearby_maps(tfd, pid, map);
241
242    unsigned int p, end;
243    unsigned int sp = r.ARM_sp;
244
245    p = sp - 64;
246    if (p > sp)
247        p = 0;
248    p &= ~3;
249    if (unwind_depth != 0) {
250        if (unwind_depth < STACK_CONTENT_DEPTH) {
251            end = sp_list[unwind_depth-1];
252        }
253        else {
254            end = sp_list[STACK_CONTENT_DEPTH-1];
255        }
256    }
257    else {
258        end = p + 256;
259        /* 'end - p' has to be multiples of 4 */
260        if (end < p)
261            end = ~7;
262    }
263
264    _LOG(tfd, only_in_tombstone, "\nstack:\n");
265
266    /* If the crash is due to PC == 0, there will be two frames that
267     * have identical SP value.
268     */
269    if (sp_list[0] == sp_list[1]) {
270        sp_depth = 1;
271    }
272    else {
273        sp_depth = 0;
274    }
275
276    while (p <= end) {
277         char *prompt;
278         char level[16];
279         long data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
280         if (p == sp_list[sp_depth]) {
281             sprintf(level, "#%02d", sp_depth++);
282             prompt = level;
283         }
284         else {
285             prompt = "   ";
286         }
287
288         /* Print the stack content in the log for the first 3 frames. For the
289          * rest only print them in the tombstone file.
290          */
291         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
292              "%s %08x  %08x  %s\n", prompt, p, data,
293              map_to_name(map, data, ""));
294         p += 4;
295    }
296    /* print another 64-byte of stack data after the last frame */
297
298    end = p+64;
299    /* 'end - p' has to be multiples of 4 */
300    if (end < p)
301        end = ~7;
302
303    while (p <= end) {
304         long data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
305         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
306              "    %08x  %08x  %s\n", p, data,
307              map_to_name(map, data, ""));
308         p += 4;
309    }
310}
311
312void dump_pc_and_lr(int tfd, int pid, mapinfo *map, int unwound_level,
313                    bool at_fault)
314{
315    struct pt_regs r;
316
317    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
318        _LOG(tfd, !at_fault, "tid %d not responding!\n", pid);
319        return;
320    }
321
322    if (unwound_level == 0) {
323        _LOG(tfd, !at_fault, "         #%02d  pc %08x  %s\n", 0, r.ARM_pc,
324             map_to_name(map, r.ARM_pc, "<unknown>"));
325    }
326    _LOG(tfd, !at_fault, "         #%02d  lr %08x  %s\n", 1, r.ARM_lr,
327            map_to_name(map, r.ARM_lr, "<unknown>"));
328}
329
330void dump_registers(int tfd, int pid, bool at_fault)
331{
332    struct pt_regs r;
333    bool only_in_tombstone = !at_fault;
334
335    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
336        _LOG(tfd, only_in_tombstone,
337             "cannot get registers: %s\n", strerror(errno));
338        return;
339    }
340
341    _LOG(tfd, only_in_tombstone, " r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
342         r.ARM_r0, r.ARM_r1, r.ARM_r2, r.ARM_r3);
343    _LOG(tfd, only_in_tombstone, " r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
344         r.ARM_r4, r.ARM_r5, r.ARM_r6, r.ARM_r7);
345    _LOG(tfd, only_in_tombstone, " r8 %08x  r9 %08x  10 %08x  fp %08x\n",
346         r.ARM_r8, r.ARM_r9, r.ARM_r10, r.ARM_fp);
347    _LOG(tfd, only_in_tombstone,
348         " ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
349         r.ARM_ip, r.ARM_sp, r.ARM_lr, r.ARM_pc, r.ARM_cpsr);
350
351#ifdef WITH_VFP
352    struct user_vfp vfp_regs;
353    int i;
354
355    if(ptrace(PTRACE_GETVFPREGS, pid, 0, &vfp_regs)) {
356        _LOG(tfd, only_in_tombstone,
357             "cannot get registers: %s\n", strerror(errno));
358        return;
359    }
360
361    for (i = 0; i < NUM_VFP_REGS; i += 2) {
362        _LOG(tfd, only_in_tombstone,
363             " d%-2d %016llx  d%-2d %016llx\n",
364              i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
365    }
366    _LOG(tfd, only_in_tombstone, " scr %08lx\n\n", vfp_regs.fpscr);
367#endif
368}
369