Re: [PATCH v7.1] Support software single step on ARM in GDBServer.

[Yao Qi <qiyaoltc at gmail dot com>]

Antoine Tremblay <antoine.tremblay@ericsson.com> writes:

> +  /* Assume all atomic sequences start with a ldrex{,b,h,d} instruction.  */
> +  insn1 = self->ops->read_memory_unsigned_integer (loc, 2, byte_order_for_code);
> +
> +  loc += 2;
> +  if (thumb_insn_size (insn1) != 4)
> +    return NULL;
> +
> +  insn2 = self->ops->read_memory_unsigned_integer (loc, 2, byte_order_for_code);
> +

This line is too long, you may define a macro to shorten
"self->ops->read_memory_unsigned_integer".

> +  loc += 2;
> +  if (!((insn1 & 0xfff0) == 0xe850
> +        || ((insn1 & 0xfff0) == 0xe8d0 && (insn2 & 0x00c0) == 0x0040)))
> +    return NULL;
> +
> +  /* Assume that no atomic sequence is longer than "atomic_sequence_length"
> +     instructions.  */
> +  for (insn_count = 0; insn_count < atomic_sequence_length; ++insn_count)
> +    {
> +      insn1
> +	= self->ops->read_memory_unsigned_integer (loc, 2,byte_order_for_code);
> +      loc += 2;
> +
> +      if (thumb_insn_size (insn1) != 4)
> +	{
> +	  /* Assume that there is at most one conditional branch in the
> +	     atomic sequence.  If a conditional branch is found, put a
> +	     breakpoint in its destination address.  */
> +	  if ((insn1 & 0xf000) == 0xd000 && bits (insn1, 8, 11) != 0x0f)
> +	    {
> +	      if (last_breakpoint > 0)
> +		return NULL; /* More than one conditional branch found,
> +			     fallback to the standard code.  */
> +
> +	      breaks[1] = loc + 2 + (sbits (insn1, 0, 7) << 1);
> +	      last_breakpoint++;
> +	    }
> +
> +	  /* We do not support atomic sequences that use any *other*
> +	     instructions but conditional branches to change the PC.
> +	     Fall back to standard code to avoid losing control of
> +	     execution.  */
> +	  else if (thumb_instruction_changes_pc (insn1))
> +	    return NULL;
> +	}
> +      else
> +	{
> +	  insn2 = self->ops->read_memory_unsigned_integer
> +	    (loc, 2, byte_order_for_code);

Format looks wrong, multiple instances of this problem in the patch.

-- 
Yao (éå)