MPU fault when allocating stack for a new thread on LPC1788, uclinux, uclibc.

[lpcware]

Content originally posted in LPCWare by repu1sion on Wed Nov 05 09:57:48 MST 2014
Having MPU fault at 0x00000000 where actually access address was a001cff4.
Described below.


/ # /opt/zpm_thread
00032 : pthread_initialize: initial thread stack bounds: bos=0x1, tos=0xffffffff
00032 : __pthread_initialize_manager: manager stack: size=8160, bos=0xa02fc008, tos=0xa02fdfe8
00032 : __pthread_initialize_manager: send REQ_DEBUG to manager thread
00032 : pthread_create: write REQ_CREATE to manager thread
00032 : pthread_create: before suspend(self)
00033 : __pthread_manager: before poll
00033 : __pthread_manager: after poll
00033 : __pthread_manager: before read
00033 : __pthread_manager: after read, n=28
00033 : __pthread_manager: got REQ_CREATE

[   13.100000]
[   13.100000] zpm_thread: unhandled MPU fault (0x08) at 0x00000000 [pc=0xa0088e4a,sp=0xa02fde08]
[   13.100000]
[   13.100000]  [fp=0x00000000]
[   13.100000]
[   13.100000]
[   13.100000] Pid: 33, comm:           zpm_thread
[   13.100000] CPU: 0    Not tainted  (2.6.33-arm1 #2)
[   13.100000] pc : [<a0088e4a>]    lr : [<a0088f8f>]    psr: 21000000
[   13.100000] sp : a02fde08  ip : a00980d8  fp : 00000000
[   13.100000] Code dump at pc [a0088e4a]:
[   13.100000] 68f8601a 683a6979 f7ff6a3b 697bffc8
[   13.100000] r10: a0095bf0  r9 : 00000000  r8 : 00000000
[   13.100000] r7 : a02fde28  r6 : a02fdf9c  r5 : 00000020  r4 : a0097fb0
[   13.100000] r3 : a001cff4  r2 : 00005000  r1 : a0018000  r0 : a009c5d0
[   13.100000] Flags: nzCv  IRQs on  FIQs on  Mode USER_26  ISA unknown  Segment user
[   13.100000] Backtrace: no frame pointer


00008dec <__heap_add_free_area>:
   free-area.  */
struct heap_free_area *
__heap_add_free_area (struct heap_free_area **heap, void *mem, size_t size,
                      struct heap_free_area *prev,
                      struct heap_free_area *next)
{
    8dec:       b580            push    {r7, lr}
    8dee:       b086            sub     sp, #24
    8df0:       af00            add     r7, sp, #0
    8df2:       60f8            str     r0, [r7, #12]
    8df4:       60b9            str     r1, [r7, #8]
    8df6:       607a            str     r2, [r7, #4]
    8df8:       603b            str     r3, [r7, #0]
  struct heap_free_area *fa = (struct heap_free_area *)
    8dfa:       68ba            ldr     r2, [r7, #8]
    8dfc:       687b            ldr     r3, [r7, #4]
    8dfe:       f1a3 030c       sub.w   r3, r3, #12
    ((char *)mem + size - sizeof (struct heap_free_area));
    8e02:       4413            add     r3, r2
    8e04:       617b            str     r3, [r7, #20]

  fa->size = size;
    8e06:       697b            ldr     r3, [r7, #20]<-- store to r3 value from r7+20 ( we have valid pointer - OK)
    8e08:       687a            ldr     r2, [r7, #4]<-- store to r2 0x5000 - OK
    8e0a:       601a            str     r2, [r3, #0]                    <-- FAIL HERE. (save 0x5000 to address a001cff4 (r3) - seems valid)

  __heap_link_free_area (heap, fa, prev, next);
    8e0c:       68f8            ldr     r0, [r7, #12]
    8e0e:       6979            ldr     r1, [r7, #20]
    8e10:       683a            ldr     r2, [r7, #0]
    8e12:       6a3b            ldr     r3, [r7, #32]
    8e14:       f7ff ffc8       bl      8da8 <__heap_link_free_area>

  return fa;
    8e18:       697b            ldr     r3, [r7, #20]
}
    8e1a:       4618            mov     r0, r3
    8e1c:       f107 0718       add.w   r7, r7, #24
    8e20:       46bd            mov     sp, r7
    8e22:       bd80            pop     {r7, pc}






(gdb) x/100x 0xa02fde28
0xa02fde28:0x000000000x000050000xa00180000xa009c5d0
0xa02fde38:0x040000210xa001cff40xa02fde500xa0088f8f
0xa02fde48:0xa009c5c40xa0097fb00x000000200x00005000
0xa02fde58:0xa00180000xa009c5d00x000000000xa009c5c4
0xa02fde68:0x000000000xa001d0000x000050000xa00a0834
0xa02fde78:0xa02fde880xa00886b90x000000000x00000000
0xa02fde88:0x000000000xa00a08340xa009c5d00x00004008
0xa02fde98:0x000000000xa00180000x000050000x00000000
0xa02fdea8:0x000000000x000000000xa02fdeb80xa0088851
0xa02fdeb8:0x000000000x000040000x000000000x00000000
0xa02fdec8:0xa02fded00xa0082b970xa02fdf3c0x00001000
0xa02fded8:0xffffbea10x000000000x000000000x00000000
0xa02fdee8:0x000000000x000000000x000040000xa02fdf88
0xa02fdef8:0x0000001c0x000000030x726f66650x00000002
0xa02fdf08:0xa02fdf200xa0082d250xa02fdf380xa02fdf34
0xa02fdf18:0xa02fdf300x000000030x000000000xa00800a5
0xa02fdf28:0x000000000xa0097fe00x000000000x00000000
0xa02fdf38:0x000000000x000000000x000000020xa0098110
0xa02fdf48:0xa02fdf500x0000002a0x000010000x00000000
0xa02fdf58:0xa02fdf800xa00828410xa0095efc0xa0097fb0
0xa02fdf68:0xa02fdf800xa00828810xa02fdf9c0x00000020
0xa02fdf78:0x000000000xa00980d80x000000000x00000003
0xa02fdf88:0xa0097fb00x000000000x000000000xa00800a5
0xa02fdf98:0x000000000x800000000x000000000xffffffef
0xa02fdfa8:0xfffffffe0x000000030x000100010x00000003
(gdb) x/100x 0xa001cff4
0xa001cff4:0x000000000x000000000x000000000x1d03d003
0xa001d004:0x280068400x6841d1f80xf00660190x4620fa3d
0xa001d014:0x490d46320xfe74f0040xe74c20010x4b091c58
0xa001d024:0x990290000xb9ab681b0xbf00e75e0x64790100
0xa001d034:0x707901000x807901000x907901000xa0790100
0xa001d044:0x507901000xb4a901000x587901000x2b00685b
0xa001d054:0xaf4af43f0x4291681a0x4668d1f80xf7ffa901
0xa001d064:0x4680fc490xf47f28000x9f00af3f0xc000f897
0xa001d074:0x0f2cf1bc0xaf38f47f0x19a61c7d0x95001b76
0xa001d084:0xf7ff46300x2e00f9010xdd3846050xe001f897
0xa001d094:0x36011e710xf1be46420xf0010f7d0xbf1c0101
0xa001d0a4:0xe000f8800x0801f04f0x2302d04b0xd02342b3
0xa001d0b4:0x5cf9b1590x297db9b20xf805bf1a0xf1081008
0xa001d0c4:0x220108010x42b333010x5cf9d0160xf081b352
0xa001d0d4:0x220000200x0008f8050x0801f1080x5cf93301
0xa001d0e4:0xd0e82a000x220033010xf08142b30xf8050c20
0xa001d0f4:0xf108c0080xd1e808010xf47f2a000x4642aef5
0xa001d104:0x462998020xf0049b010xf1b0fb130xd01a3fff
0xa001d114:0x491746020xf00446200x4628fdf30xf9b4f006
0xa001d124:0xe6c820010xbf1a297d0x1008f8050x0801f108
0xa001d134:0xe7d322010xf7ff46200x2001fd110x4b0de6bb
0xa001d144:0x2201e7610x4620e7b10xfd08f7ff0xf0064628
0xa001d154:0x2001f99b0x4620e6af0x4631462b0xfd9af7ff
0xa001d164:0xf7ffe7160x4630fcfb0xf98ef0060xe6a22001
0xa001d174:0x587901000xb4a901000xe92d4b760x681a01f0


[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0x00000000 - 0x00001000   (   4 kB)
[    0.000000]     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
[    0.000000]     vmalloc : 0x00000000 - 0xffffffff   (4095 MB)
[    0.000000]     lowmem  : 0xa0000000 - 0xa0800000   (   8 MB)
[    0.000000]     modules : 0xa0000000 - 0x01000000   (1552 MB)
[    0.000000]       .init : 0xa0008000 - 0xa00e4000   ( 880 kB)
[    0.000000]       .text : 0xa00e4000 - 0xa0197000   ( 716 kB)
[    0.000000]       .data : 0xa0198000 - 0xa01a7c80   (  64 kB)

[    4.700000] Freeing init memory: 880K


Any suggestions are welcome.

[lpcware]

Content originally posted in LPCWare by repu1sion on Thu Nov 06 07:52:29 MST 2014
What I actually did - disabled CONFIG_MPU in kernel and it started to work.
After that I found that my u-boot is custom fork and probably doesn't setup MPU well.
Without CONFIG_MPU everything started to work great.