Hello,

I have a stm32h7 board, based on the stm32h743zi2 nucleo.

I have activated the watchdog.

The method to do the kthread was copied from this :

https://github.com/apache/nuttx/blob/master/boards/arm/stm32/photon/src/stm32_wdt.c#LL146C7-L146C7

The watchdog works, the system is stable


But now, the nsh 'ps' command ends up with a crash when trying to list the kthread that resets the watchdog.


The problem has appeared between current trunk and revision 13d823f30710e6fabd3d6429a03bc37e1086c9e7


Here is the GDB session, a bit after cmd_ps is entered:

(pid 4 is the watchog maintenance kthread created like in the file above)


open (path=0x3800c770 "/proc/4/cmdline", oflags=1) at vfs/fs_open.c:447
447       if (fd < 0)
(gdb) n
453       leave_cancellation_point();
(gdb)
454       return fd;
(gdb)
455     }
(gdb)
nsh_readfile (vtbl=0x38005688, cmd=0x807ab7c "ps", filepath=0x3800c770 "/proc/4/cmdline", buffer=0x380056b0 "  0.0%", buflen=512)
    at nsh_fsutils.c:219
219       if (fd < 0)
(gdb) print fd
$1 = 4
(gdb) n
229       ntotal    = 0;          /* No bytes read yet */
(gdb)
230       *buffer   = '\0';       /* NUL terminate the empty buffer */
(gdb)
231       bufptr    = buffer;     /* Working pointer */
(gdb)
232       remaining = buflen - 1; /* Reserve one byte for a NUL terminator */
(gdb)
233       ret       = ERROR;      /* Assume failure */
(gdb)
237           nread = read(fd, bufptr, remaining);
(gdb) s
read (fd=4, buf=0x380056b0, nbytes=511) at vfs/fs_read.c:166
166       enter_cancellation_point();
(gdb) n
170       ret = nx_read(fd, buf, nbytes);
(gdb) s
nx_read (fd=4, buf=0x380056b0, nbytes=511) at vfs/fs_read.c:132
132       ret = (ssize_t)fs_getfilep(fd, &filep);
(gdb) n
133       if (ret < 0)
(gdb)
140       return file_read(filep, buf, nbytes);
(gdb) s
file_read (filep=0x38002e40, buf=0x380056b0, nbytes=511) at vfs/fs_read.c:67
67        int ret = -EBADF;
(gdb) n
69        DEBUGASSERT(filep);
(gdb)
70        inode = filep->f_inode;
(gdb)
74        if ((filep->f_oflags & O_RDOK) == 0)
(gdb)
85        else if (inode != NULL && inode->u.i_ops && inode->u.i_ops->read)
(gdb)
92            ret = (int)inode->u.i_ops->read(filep,
(gdb) s
procfs_read (filep=0x38002e40, buffer=0x380056b0 "", buflen=511) at procfs/fs_procfs.c:445
445       handler = (FAR struct procfs_file_s *)filep->f_priv;
(gdb) n
446       DEBUGASSERT(handler);
(gdb)
450       return handler->procfsentry->ops->read(filep, buffer, buflen);
(gdb) s
proc_read (filep=0x38002e40, buffer=0x380056b0 "", buflen=511) at procfs/fs_procfsproc.c:1552
1552      procfile = (FAR struct proc_file_s *)filep->f_priv;
(gdb) n
1553      DEBUGASSERT(procfile != NULL);
(gdb)
1557      tcb = nxsched_get_tcb(procfile->pid);
(gdb)
1558      if (tcb == NULL)
(gdb) print tcb
$2 = (struct tcb_s *) 0x38003f28
(gdb) print *tcb
$3 = {flink = 0x38008640, blink = 0x0, group = 0x38003fe0, pid = 4, sched_priority = 100 'd', init_priority = 100 'd',   start = 0x802fc91 <nxtask_start>, entry = {pthread = 0x806ecf1 <wdog_daemon>, main = 0x806ecf1 <wdog_daemon>}, task_state = 6 '\006',   flags = 4138, lockcount = 0, cpcount = 0, errcode = 0, timeslice = 200, waitdog = {next = 0x38005a40, arg = 939540264,     func = 0x802ecdd <nxsig_timeout>, lag = 316}, adj_stack_size = 960, stack_alloc_ptr = 0x38004328, stack_base_ptr = 0x38004368, waitobj = 0x0,   sigprocmask = {_elem = {0, 0}}, sigwaitmask = {_elem = {0, 0}}, sigpendactionq = {head = 0x0, tail = 0x0}, sigpostedq = {head = 0x0,     tail = 0x0}, sigunbinfo = {si_signo = 255 '\377', si_code = 2 '\002', si_errno = 110 'n', si_value = {sival_int = 0, sival_ptr = 0x0},     si_user = 0x0}, mhead = 0x0, ticks = 0, xcp = {sigdeliver = 0x0, saved_regs = 0x0, regs = 0x3800449c},
  name = "watchdog\000\000\000\000\000\000\000\000"}
(gdb) n
1566      switch (procfile->node->node)
(gdb) n
1573          ret = proc_cmdline(procfile, tcb, buffer, buflen, filep->f_pos);
(gdb) s
proc_cmdline (procfile=0x3800caa0, tcb=0x38003f28, buffer=0x380056b0 "", buflen=511, offset=0) at procfs/fs_procfsproc.c:664
664       remaining = buflen;
(gdb) n
665       totalsize = 0;
(gdb)
670       name       = tcb->name;
(gdb)
674       linesize   = strlen(name);
(gdb)
675       memcpy(procfile->line, name, linesize);
(gdb) print linesize
$4 = 8
(gdb) n
676       copysize   = procfs_memcpy(procfile->line, linesize, buffer, remaining,
(gdb) n
679       totalsize += copysize;
(gdb) print copysize
$5 = 8
(gdb) n
680       buffer    += copysize;
(gdb) n
681       remaining -= copysize;
(gdb) n
683       if (totalsize >= buflen)
(gdb) print remaining
$6 = 503
(gdb) n
690       linesize   = group_argvstr(tcb, procfile->line, remaining);
(gdb) s
group_argvstr (tcb=0x38003f28, args=0x3800caac "watchdog", size=503) at group/group_argvstr.c:61
61        size_t n = 0;
(gdb) n
68        if (!tcb || !tcb->group || !tcb->group->tg_info)
(gdb)
84        if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
(gdb)
93            FAR char **argv = tcb->group->tg_info->argv + 1;
(gdb)
95            while (*argv != NULL && n < size)
(gdb)
97                n += snprintf(args + n, size - n, " %s", *argv++);
(gdb) n

*CRASH*

When I just run, the stack dump shows a crash at

Fault:   IRQ: 3 regs: 0x380037ec
arm_busfault:   BASEPRI: 000000f0 PRIMASK: 00000000 IPSR: 00000003 CONTROL: 00000000 arm_busfault:   CFSR: 00008200 HFSR: 40000000 DFSR: 00000000 BFAR: 00000003 AFSR: 00000000
arm_busfault: Bus Fault Reason:
arm_busfault:   Precise data bus error
_assert: Current Version: NuttX bca 12.0.0-RC1 2eac660ff6-dirty May 11 2023 15:27:06 arm _assert: Assertion failed panic: at file: armv7-m/arm_busfault.c:106 task: nsh_main 0x8039c41
up_dump_register: R0: 00000003 R1: ffffffff R2: 38003a1c  R3: 00000003
up_dump_register: R4: 08039e89 R5: 3800571e R6: 38005734  FP: 380038c0
up_dump_register: R8: 00000000 SB: 00000000 SL: 00000000 R11: 00000000
up_dump_register: IP: a0000000 SP: 380038c0 LR: 08035537  PC: 080367a8
up_dump_register: xPSR: a1000000 PRIMASK: 00000000 CONTROL: 00000000

PC=nuttx/libs/libc/string/lib_strnlen.c:37 (discriminator 3)
LR=nuttx/libs/libc/stdio/lib_libvsprintf.c:940 (discriminator 4)

This is trying to measure the length of the command line

Running again with a breakpoint in proc_cmdline:

Breakpoint 1, proc_cmdline (procfile=0x3800caa0, tcb=0x38003f28, buffer=0x380056b0 "", buflen=511, offset=0) at procfs/fs_procfsproc.c:664
664       remaining = buflen;
(gdb) print *tcb
$4 = {flink = 0x38008640, blink = 0x0, group = 0x38003fe0, pid = 4, sched_priority = 100 'd', init_priority = 100 'd',   start = 0x802fc91 <nxtask_start>, entry = {pthread = 0x806ecf1 <wdog_daemon>, main = 0x806ecf1 <wdog_daemon>}, task_state = 6 '\006',   flags = 4138, lockcount = 0, cpcount = 0, errcode = 0, timeslice = 200, waitdog = {next = 0x0, arg = 939540264,     func = 0x802ecdd <nxsig_timeout>, lag = 419}, adj_stack_size = 960, stack_alloc_ptr = 0x38004328, stack_base_ptr = 0x38004368, waitobj = 0x0,   sigprocmask = {_elem = {0, 0}}, sigwaitmask = {_elem = {0, 0}}, sigpendactionq = {head = 0x0, tail = 0x0}, sigpostedq = {head = 0x0,     tail = 0x0}, sigunbinfo = {si_signo = 255 '\377', si_code = 2 '\002', si_errno = 110 'n', si_value = {sival_int = 0, sival_ptr = 0x0},     si_user = 0x0}, mhead = 0x0, ticks = 0, xcp = {sigdeliver = 0x0, saved_regs = 0x0, regs = 0x3800449c},
  name = "watchdog\000\000\000\000\000\000\000\000"}

(gdb) print *tcb->group
$5 = {flink = 0x38002b40, tg_pid = 4, tg_ppid = 0, tg_flags = 0 '\000', tg_nmembers = 1 '\001', tg_mxmembers = 4 '\004', tg_members = 0x38004078,   tg_nwaiters = 0 '\000', tg_waitflags = 0 '\000', tg_exitsem = {semcount = 0, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}},   tg_statloc = 0x0, tg_joinlock = {sem = {semcount = 1, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, tg_joinhead = 0x0,   tg_jointail = 0x0, tg_info = 0x38004090, tg_sigactionq = {head = 0x0, tail = 0x0}, tg_sigpendingq = {head = 0x0, tail = 0x0}, tg_envp = 0x0,   tg_envc = 0, itimer = 0x0, tg_filelist = {fl_lock = {sem = {semcount = 1, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1},     fl_rows = 1 '\001', fl_files = 0x38004250}, tg_mm_map = {mm_map_sq = {head = 0x0, tail = 0x0}, mm_map_mutex = {mutex = {sem = {semcount = 1,           flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, count = 0}}}

(gdb) print *tcb->group->tg_info
$6 = {ta_lock = {sem = {semcount = 1, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, argv = 0x38004350,   ta_tlsset = 0 '\000', ta_tlsdtor = {0x0, 0x0, 0x0, 0x0}, ta_getopt = {go_optarg = 0x0, go_opterr = 0, go_optind = 0, go_optopt = 0,     go_optptr = 0x0, go_binitialized = false}, ta_umask = 0, ta_streamlist = {sl_lock = {sem = {semcount = 1, flags = 0 '\000', waitlist = {           head = 0x0, tail = 0x0}}, holder = -1}, sl_std = {{fs_next = 0x0, fs_lock = {mutex = {sem = {semcount = 1, flags = 0 '\000',               waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, count = 0}, fs_fd = 0, fs_bufstart = 0x38004110 "",         fs_bufend = 0x38004150 "\001", fs_bufpos = 0x38004110 "", fs_bufread = 0x38004110 "", fs_buffer = '\000' <repeats 63 times>,         fs_oflags = 1, fs_flags = 12 '\f', fs_nungotten = 0 '\000', fs_ungotten = "\000"}, {fs_next = 0x0, fs_lock = {mutex = {sem = {               semcount = 1, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, count = 0}, fs_fd = 1,         fs_bufstart = 0x38004184 "", fs_bufend = 0x380041c4 "\006", fs_bufpos = 0x38004184 "", fs_bufread = 0x38004184 "",         fs_buffer = '\000' <repeats 63 times>, fs_oflags = 6, fs_flags = 12 '\f', fs_nungotten = 0 '\000', fs_ungotten = "\000"}, {fs_next = 0x0,         fs_lock = {mutex = {sem = {semcount = 1, flags = 0 '\000', waitlist = {head = 0x0, tail = 0x0}}, holder = -1}, count = 0}, fs_fd = 2,         fs_bufstart = 0x380041f8 "", fs_bufend = 0x38004238 "\006", fs_bufpos = 0x380041f8 "", fs_bufread = 0x380041f8 "",         fs_buffer = '\000' <repeats 63 times>, fs_oflags = 6, fs_flags = 12 '\f', fs_nungotten = 0 '\000', fs_ungotten = "\000"}}, sl_head = 0x0,
    sl_tail = 0x0}}

We see that argv = 0x38004350, which is in the stack: stack_alloc_ptr = 0x38004328, stack_base_ptr = 0x38004368

(gdb) print (uint32_t[10])*tcb->group->tg_info->argv
$8 = {939541660, 3, 2, 939541660, 939541352, 134362499, 0, 0, 939541660, 3}
(gdb) print (char*[10])*tcb->group->tg_info->argv
$9 = {0x3800449c "pE", 0x3 "", 0x2 "", 0x3800449c "pE", 0x38004368 "", 0x8023583 <arm_hardfault+78> "F+\340{j\003\360\200C", 0x0, 0x0,
  0x3800449c "pE", 0x3 ""}

This is not good! Too many non null values in that array, some of them are not pointers! The value 3 is found in the BFAR of the crash dump.

kthread_create was called with argv = NULL

This calls kthread_create_with_stack with argv = NULL

This calls nxthread_create with argv = NULL

This calls nxtask_init with argv = NULL, envp=NULL

goto sched/task/task_init.c

This goes to nxtask_setup_arguments with argv=NULL

goto sched/task/task_setup.c

This calls nxtask_setup_stackargs

Looks like this function does the right thing.

I should get argc=0, allocation of two pointers, one for the task name and one for the final null arg.


Then what is happening? Why do I see invalid values in the argv array?


Can someone help me? Can someone try to reproduce this?

I have built this image with a make distclean, apply config, make, so I dont expect dangling files.



Thanks,

Sebastien


Reply via email to