ARM 'coprocessor' register reads appear to be writing to the wrong location

[GregIthaca]

Working with 6.2, configurable machine, ARM Cortex-M. The problem I believe lies here:

avatar-qemu/hw/avatar/arm_helper.c

Line 80 in a487945

stl_p(buf, env->banked_r13[bank_number(ARM_CPU_MODE_USR)]); return 4;

The buf passed to banked_gdb_set_reg is a uint8_t * and this works correctly. However, the buf passed to banked_gdb_get_reg is actually a GByteArray *. The stl_p operation (eventually translated to a memcpy call) writes 4 bytes to the destination of the pointer... which is overwriting the pointer contained in the first member of the GByteArray structure and not actually storing to the byte array. Furthermore, it does not update the length field of the GByteArray. Shortly thereafter, qemu-system-arm terminates with a segmentation violation.

This is pretty easy to reproduce: start the emulator with an appropriate configuration, then (assuming gdb port 1234) connect with arm-none-eabi-gdb:

target remote :1234
info reg

The correct operation here is probably just gdb_get_reg32.