Hi Lassi, Thank you so much for clarifying! I get the desired output now. :)
Regards, Arun On Tue, Apr 21, 2015 at 9:30 PM, Lassi Tuura <[email protected]> wrote: > Hey Arun, > > On Tue, Apr 21, 2015 at 2:32 AM, Arun Prakash Jana <[email protected] > > wrote: > >> Hi, >> >> I am calling unw_create_addr_space() in the following lines: >> -------------------------- >> /* Create address space for little endian */ >> addrspace = unw_create_addr_space(&accessors, 0); >> if (!addrspace) { >> fprintf(stderr, "unw_create_addr_space failed\n"); >> return -1; >> } >> -------------------------- >> > > You haven't initialised accessors with anything at this point. I think you > are supposed to just pass in _UPT_accessors as per man page, but I haven't > really ever used the ptrace support. > > >> >> >> And I can verify from GDB that it is initialized: >> -------------------------- >> (gdb) bt full >> #0 0x0000000000000000 in ?? () >> No symbol table info available. >> #1 0x00007ffff7bbeee4 in _Ux86_64_init_remote () from >> /usr/lib/x86_64-linux-gnu/libunwind-x86_64.so.8 >> No symbol table info available. >> #2 0x0000000000400d8c in main (argc=2, argv=0x7fffffffe0e8) at >> unwind.c:87 >> addrspace = 0x603010 >> uptinfo = 0x60dab0 >> accessors = {find_proc_info = 0x7ffff7602c58, put_unwind_info = >> 0x1f25bc2, get_dyn_info_list_addr = 0x7fffffffdce0, >> access_mem = 0x7ffff7de4991 <_dl_lookup_symbol_x+305>, >> access_reg = 0x0, access_fpreg = 0x7ffff7fe0a58, resume = 0x7ffff7fe1000, >> get_proc_name = 0x7ffff7dda77c} >> > > All of these addresses look to be junk and don't point to any procedures. > So when the tracing code calls them as functions, you'll just jump to > random memory addresses. > > >> cursor = {opaque = {6347440, 6303760, 4294967296, 4294969506, >> 140737354127864, 140737488346688, 140737488346496, 140737354009176, 1, 0, >> 2, >> 1, 2, 2, 2, 3, 2, 4, 2, 5, 2, 6, 2, 7, 2, 8, 2, 9, 2, 10, 2, >> 11, 2, 12, 2, 13, 2, 14, 2, 15, 2, 16, 2, 140737354127864, >> 140737351887448, 7, 140737351885856, 140737351884800, >> 140737488346816, 140737351936639, 140733193388033, 0, 0, 140737351925404, >> 140737488346672, 1700966438, 0, 1, 0, 140737351927416, 0, >> 140737488346656, 140737354113376, 140737488346928, 140737354113496, >> 140737488346912, 0, 140737351925404, 0, 4131212846, 3, 8, >> 140737354007936, 140737351927830, 0, 140737488346768, 140737343610152, >> 140737488347040, 140737343660456, 64550200, 140737488347024, >> 140737354132200, 0, 140737354008048, 140737354010624, 4196003, >> 140737343663480, 4195176, 4294967296, 4294969392, 0, >> 140737488347224, 140737488347184, 140737354008048, 1, 140737354130720, >> 140737354129864, 140737351928209, 0, 140737354008048, 1, 0, >> 140733193388033, 140737354129864, 0, 0, 0, 0, 0, 140737354130720, >> 140737488347040, 140737488347024, 4131212846, 4196003, >> 4294967295, 140737488347392, 140737343660456, 140737354010624, >> 140737354129864, >> 0, 1, 4198109, 140737488347136, 0, 4198032, 4196864, >> 140737488347360}} >> RIP = 140737354013160 >> RBP = 140737488346080 >> PID = 26450 >> ret = 26450 >> wait_loops = 18 >> wait_time = 1000 >> waitstatus = 4991 >> stopped = 1 >> (gdb) >> -------------------------- >> >> >> Regards, >> >> Arun >> > > Cheers, > Lassi > > >> >> >> On Tue, Apr 21, 2015 at 12:09 AM, Lassi Tuura <[email protected]> wrote: >> >>> It doesn't look like you are initialising your unw_accessors_t accessors. >>> From libunwind-ptrace man page: >>> >>> An application that wants to use the _UPT-facility first needs to create >>> a new libunwind address-space that represents the target process. This is >>> done by calling unw_create_addr_space(). In many cases, the application >>> will simply want to pass the address of _UPT_accessors as the first >>> argument to this routine >>> >>> On Mon, Apr 20, 2015 at 1:42 PM, Arun Prakash Jana < >>> [email protected]> wrote: >>> >>>> Hi, >>>> >>>> I am writing a small test program to check how libunwind can be used to >>>> trace a remote program. >>>> >>>> A call to unw_init_remote() throws SIGSEGV. >>>> >>>> *Relevant code snippet:* >>>> ------------------ >>>> unw_addr_space_t addrspace; >>>> struct UPT_info *uptinfo; >>>> unw_accessors_t accessors; >>>> unw_cursor_t cursor; >>>> unw_word_t RIP, RBP; >>>> >>>> pid_t PID = 1; >>>> int ret = 0; >>>> >>>> if (argc !=2) { >>>> fprintf(stderr, "Usage: unwind PID\n"); >>>> return -1; >>>> } >>>> >>>> if ((PID = atoi(argv[1])) <= 0) { >>>> fprintf(stderr, "Valid PID please!\n"); >>>> return -1; >>>> } >>>> >>>> fprintf(stdout, "Tracing PID: %d\n", PID); >>>> >>>> /* Create address space for little endian */ >>>> addrspace = unw_create_addr_space(&accessors, 0); >>>> if (!addrspace) { >>>> fprintf(stderr, "unw_create_addr_space failed\n"); >>>> return -1; >>>> } >>>> >>>> uptinfo = (struct UPT_info *)_UPT_create(PID); >>>> if (!uptinfo) { >>>> fprintf(stderr, "_UPT_create failed\n"); >>>> goto bail; >>>> } >>>> >>>> ret = unw_init_remote(&cursor, addrspace, uptinfo); >>>> if (ret < 0) { >>>> fprintf(stderr, "unw_init_remote failed\n"); >>>> goto bail; >>>> } >>>> ------------------ >>>> >>>> *strace output:* >>>> ------------------ >>>> > strace ./unwind 8423 >>>> execve("./unwind", ["./unwind", "8423"], [/* 85 vars */]) = 0 >>>> brk(0) = 0x1cdd000 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cc9000 >>>> access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=81750, ...}) = 0 >>>> mmap(NULL, 81750, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fc136cb5000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/usr/lib/x86_64-linux-gnu/libunwind-x86_64.so.8", >>>> O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, >>>> "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0p\27\0\0\0\0\0\0"..., 832) = >>>> 832 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=67608, ...}) = 0 >>>> mmap(NULL, 2223816, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc13688a000 >>>> mprotect(0x7fc13689a000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc136a99000, 8192, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0xf000) = 0x7fc136a99000 >>>> mmap(0x7fc136a9b000, 57032, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fc136a9b000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/usr/lib/x86_64-linux-gnu/libunwind-ptrace.so.0", >>>> O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, >>>> "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\17\0\0\0\0\0\0"..., 832) >>>> = 832 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=14528, ...}) = 0 >>>> mmap(NULL, 2109736, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc136686000 >>>> mprotect(0x7fc136689000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc136888000, 8192, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7fc136888000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, >>>> "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\37\2\0\0\0\0\0"..., >>>> 832) = 832 >>>> fstat(3, {st_mode=S_IFREG|0755, st_size=1840928, ...}) = 0 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cb4000 >>>> mmap(NULL, 3949248, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc1362c1000 >>>> mprotect(0x7fc13647c000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc13667b000, 24576, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1ba000) = 0x7fc13667b000 >>>> mmap(0x7fc136681000, 17088, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fc136681000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/usr/lib/x86_64-linux-gnu/libunwind.so.8", O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, >>>> "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0000\37\0\0\0\0\0\0"..., 832) >>>> = 832 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=51192, ...}) = 0 >>>> mmap(NULL, 2207464, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc1360a6000 >>>> mprotect(0x7fc1360b2000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc1362b1000, 8192, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0xb000) = 0x7fc1362b1000 >>>> mmap(0x7fc1362b3000, 57064, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fc1362b3000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/lib/x86_64-linux-gnu/liblzma.so.5", O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320 >>>> \0\0\0\0\0\0"..., 832) = 832 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=137400, ...}) = 0 >>>> mmap(NULL, 2232456, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc135e84000 >>>> mprotect(0x7fc135ea5000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc1360a4000, 8192, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x20000) = 0x7fc1360a4000 >>>> close(3) = 0 >>>> access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or >>>> directory) >>>> open("/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3 >>>> read(3, >>>> "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\16\0\0\0\0\0\0"..., >>>> 832) = 832 >>>> fstat(3, {st_mode=S_IFREG|0644, st_size=14664, ...}) = 0 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cb3000 >>>> mmap(NULL, 2109744, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, >>>> 0) = 0x7fc135c80000 >>>> mprotect(0x7fc135c83000, 2093056, PROT_NONE) = 0 >>>> mmap(0x7fc135e82000, 8192, PROT_READ|PROT_WRITE, >>>> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7fc135e82000 >>>> close(3) = 0 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cb2000 >>>> mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cb0000 >>>> arch_prctl(ARCH_SET_FS, 0x7fc136cb0780) = 0 >>>> mprotect(0x7fc13667b000, 16384, PROT_READ) = 0 >>>> mprotect(0x7fc135e82000, 4096, PROT_READ) = 0 >>>> mprotect(0x7fc1360a4000, 4096, PROT_READ) = 0 >>>> mprotect(0x7fc1362b1000, 4096, PROT_READ) = 0 >>>> mprotect(0x7fc136888000, 4096, PROT_READ) = 0 >>>> mprotect(0x7fc136a99000, 4096, PROT_READ) = 0 >>>> mprotect(0x601000, 4096, PROT_READ) = 0 >>>> mprotect(0x7fc136ccb000, 4096, PROT_READ) = 0 >>>> munmap(0x7fc136cb5000, 81750) = 0 >>>> fstat(1, {st_mode=S_IFREG|0664, st_size=5320, ...}) = 0 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cc8000 >>>> brk(0) = 0x1cdd000 >>>> brk(0x1d08000) = 0x1d08000 >>>> rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cc7000 >>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, >>>> 0) = 0x7fc136cc6000 >>>> mincore(0x7ffd4ae65b3f, 1, 0x7ffd4ae65b3f) = -1 EINVAL (Invalid >>>> argument) >>>> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 >>>> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0} --- >>>> +++ killed by SIGSEGV +++ >>>> fish: Job 1, "strace ./unwind 8423 > strace.log 2>&1" terminated by >>>> signal SIGSEGV (Address boundary error) >>>> ------------------ >>>> >>>> I am on Ubuntu 14.04 (arch: x86_64). Can someone please explain what >>>> I'm doing wrong? >>>> >>>> Regards, >>>> >>>> Arun >>>> >>>> _______________________________________________ >>>> Libunwind-devel mailing list >>>> [email protected] >>>> https://lists.nongnu.org/mailman/listinfo/libunwind-devel >>>> >>>> >>> >> >
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