ARM/mem: handle data aborts gracefully for md
...
Sometimes memory ranges contain inaccessible registers which trigger a
data abort when accessed. To handle this gracefully, we extend the data
abort exception handler to ignore the exception when configured to do
so.
This allows detecting inaccessible memory from the md command. It will
show XX for unreadable bytes instead.
The previous behaviour:
barebox@TI AM335x BeagleBone:/ md 0x50000000
unable to handle paging request at address 0x500000ac
pc : [<8fe2e0dc>] lr : [<8fe2e0b9>]
sp : 8ffff898 ip : 00000024 fp : 00000000
r10: 8bfa0204 r9 : 00000000 r8 : 8bfa0204
r7 : 00000100 r6 : 50000000 r5 : 8bfa0204 r4 : 00000004
r3 : 00000f00 r2 : 000000ac r1 : 00000004 r0 : 00000014
Flags: nZCv IRQs off FIQs on Mode SVC_32
[<8fe2e0dc>] (memcpy_sz+0x40/0x48) from [<8fe2f337>] (mem_read+0x3b/0x48)
[<8fe2f337>] (mem_read+0x3b/0x48) from [<8fe2bb13>] (cdev_read+0x25/0x2e)
[<8fe2bb13>] (cdev_read+0x25/0x2e) from [<8fe2c15b>] (devfs_read+0x1b/0x1e)
[<8fe2c15b>] (devfs_read+0x1b/0x1e) from [<8fe2df5b>] (__read+0x43/0x5c)
[<8fe2df5b>] (__read+0x43/0x5c) from [<8fe2e61f>] (read+0x2b/0x48)
[<8fe2e61f>] (read+0x2b/0x48) from [<8fe1e4a5>] (do_mem_md+0xc1/0x144)
[<8fe1e4a5>] (do_mem_md+0xc1/0x144) from [<8fe02889>] (execute_command+0x21/0x48)
[<8fe02889>] (execute_command+0x21/0x48) from [<8fe061c1>] (run_list_real+0x549/0x634)
[<8fe061c1>] (run_list_real+0x549/0x634) from [<8fe05b43>] (parse_stream_outer+0xdb/0x174)
[<8fe05b43>] (parse_stream_outer+0xdb/0x174) from [<8fe06435>] (run_shell+0x29/0x54)
[<8fe06435>] (run_shell+0x29/0x54) from [<8fe02889>] (execute_command+0x21/0x48)
[<8fe02889>] (execute_command+0x21/0x48) from [<8fe061c1>] (run_list_real+0x549/0x634)
[<8fe061c1>] (run_list_real+0x549/0x634) from [<8fe05efb>] (run_list_real+0x283/0x634)
[<8fe31e1d>] (unwind_backtrace+0x1/0x64) from [<8fe24e61>] (panic+0x1d/0x34)
[<8fe24e61>] (panic+0x1d/0x34) from [<8fe322c1>] (do_exception+0xd/0x10)
[<8fe322c1>] (do_exception+0xd/0x10) from [<8fe32329>] (do_data_abort+0x21/0x2c)
[<8fe32329>] (do_data_abort+0x21/0x2c) from [<8fe31fe8>] (data_abort+0x48/0x60)
The new behaviour:
barebox@TI AM335x BeagleBone:/ md 0x50000000
50000000: 00000060 00000000 00000000 00000000 `...............
50000010: 00000000 00000001 00000000 00000000 ................
50000020: 00000000 00000000 00000000 00000000 ................
50000030: 00000000 00000000 00000000 00000000 ................
50000040: 00001ff0 400000ac 00000211 00000000 .......@........
50000050: 00000a00 00000001 00000000 00000000 ................
50000060: 00000000 00101001 22060514 10057016 ...........".p..
50000070: 010f1111 8f070000 00000f40 00000000 ........@.......
50000080: 00000000 00000000 00000000 00000000 ................
50000090: 00001000 00101001 22060514 10057016 ...........".p..
500000a0: 010f1111 8f070000 00000f00 XXXXXXXX ................
500000b0: XXXXXXXX XXXXXXXX 00000000 00000000 ................
500000c0: 00001000 00101001 22060514 10057016 ...........".p..
500000d0: 010f1111 8f070000 00000f00 XXXXXXXX ................
500000e0: XXXXXXXX XXXXXXXX 00000000 00000000 ................
500000f0: 00001000 00101001 22060514 10057016 ...........".p..
The current implementation breaks everything except ARM and takes several
shortcuts which need to be implemented more cleanly. Suggestions are very
welcome!
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Jan Luebbe
authored
on 3 Aug 2014
Sascha Hauer
committed
on 27 Feb 2015
