Question w.r.t. crash inside select call from libbsd.

[Karel Gardas]

  Hello,

I'm debugging crash inside the select call from libbsd library. The code 
comes from few days old RTEMS and few days old libbsd trees. My naive 
configuration for the RTEMS is below.

The crash backtrace is:

_CPU_Fatal_halt (source=source at entry=9, error=<optimized out>, 
error at entry=604203640) at ../../../cpukit/score/cpu/arm/cpu.c:203
203       while ( true ) {
(gdb) where
#0  _CPU_Fatal_halt (source=source at entry=9, error=<optimized out>, 
error at entry=604203640)
     at ../../../cpukit/score/cpu/arm/cpu.c:203
#1  0x080fb9b4 in _Terminate 
(the_source=the_source at entry=RTEMS_FATAL_SOURCE_EXCEPTION,
     the_error=604203640) at ../../../cpukit/score/src/interr.c:58
#2  0x08104e56 in rtems_fatal (fatal_code=<optimized out>,
     fatal_source=RTEMS_FATAL_SOURCE_EXCEPTION) at 
../../../cpukit/include/rtems/fatal.h:160
#3  _ARM_Exception_default (frame=<optimized out>)
     at ../../../cpukit/score/cpu/arm/arm-exception-default.c:37
#4  <signal handler called>
#5  _bsd_uma_zalloc_arg (zone=0x9, udata=udata at entry=0x0, 
flags=flags at entry=2)
     at ../../freebsd/sys/vm/uma_core.c:2624
#6  0x0807c180 in uma_zalloc (flags=2, zone=<optimized out>)
     at ../../freebsd/sys/vm/uma.h:356
#7  0x080b51b8 in rtems_bsd_thread_create (thread=0xd0003048 
<_RTEMS_tasks_Objects>,
     wait=<optimized out>) at ../../rtemsbsd/rtems/rtems-kernel-thread.c:93
#8  0x080b5250 in rtems_bsd_get_curthread (wait=0)
     at ../../rtemsbsd/rtems/rtems-kernel-thread.c:116
#9  0x0807e59a in select (nfds=1, readfds=readfds at entry=0xd000da30,
     writefds=writefds at entry=0xd000da38, errorfds=errorfds at entry=0x0,
     _bsd_timeout=_bsd_timeout at entry=0x0) at 
../../freebsd/sys/kern/sys_generic.c:1170


When I put breakpoint here and there I found strange fact that zone = 
0x0 in frame #5 and not 0x9:

Breakpoint 1, _bsd_uma_zalloc_arg (zone=0x0, udata=udata at entry=0x0, 
flags=flags at entry=2) at ../../freebsd/sys/vm/uma_core.c:2562
2562    {
(gdb) next
2680                    bucket_free(zone, bucket, udata);
(gdb) next
2622            critical_enter();
(gdb) next
196       cpu_self->thread_dispatch_disable_level = disable_level + 1;
(gdb) next
2622            critical_enter();
(gdb) next
2624            cache = &zone->uz_cpu[cpu];
(gdb) next
_ARMV7M_Exception_default () at 
../../../cpukit/score/cpu/arm/armv7m-exception-default.c:51
51        __asm__ volatile (
(gdb)


so with zone being NULL the crash is expected here. However I'm still 
curious if this is libbsd issue or my issue with naive configuration?

The platform is STM32H757i-eval board, the linking is using flash_sdram 
configuration. The board provides 16MB of SDRAM so hopefully this should 
be enough even for libbsd... The board configuration is more or less 
default except disabling of MPU alignment. If I don't do this, my 
testing app (quickjs) would not fit 2MB of CPU flash. When MPU alignment 
is disabled, I'm on 1.4MB of flash consumption (before disabling 2.3MB)

Any ideas how to debug this more are highly appreciated!

Thanks!
Karel

<preceeding code here comes from default-configuration.c>

/*
  * Configure LibBSD.
  */

#define RTEMS_BSD_CONFIG_NET_PF_UNIX
#define RTEMS_BSD_CONFIG_NET_IF_BRIDGE
#define RTEMS_BSD_CONFIG_NET_IF_LAGG
#define RTEMS_BSD_CONFIG_NET_IF_VLAN
#define RTEMS_BSD_CONFIG_BSP_CONFIG
#define RTEMS_BSD_CONFIG_TERMIOS_KQUEUE_AND_POLL
#define RTEMS_BSD_CONFIG_INIT

#include <machine/rtems-bsd-config.h>

/*
  * Configure RTEMS.
  */

/* This is enough to get a basic main() up. */
#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
#define CONFIGURE_UNIFIED_WORK_AREAS
#define CONFIGURE_STACK_CHECKER_ENABLED

/* on smaller architectures lower the number or resources */
#define CONFIGURE_UNLIMITED_OBJECTS
#define CONFIGURE_MAXIMUM_USER_EXTENSIONS 8
#define CONFIGURE_MAXIMUM_DRIVERS 16
#define CONFIGURE_MAXIMUM_FILE_DESCRIPTORS 32

/* Include basic device drivers needed to call delays */
#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_STUB_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_ZERO_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_LIBBLOCK

#define CONFIGURE_MAXIMUM_PROCESSORS CPU_MAXIMUM_PROCESSORS

/* #define CONFIGURE_DISABLE_BSP_SETTINGS*/

#define CONFIGURE_VERBOSE_SYSTEM_INITIALIZATION

#define CONFIGURE_MINIMUM_TASK_STACK_SIZE ( CPU_STACK_MINIMUM_SIZE * 4 )

#define CONFIGURE_INIT

#include <rtems/confdefs.h>