[PATCH] Fix ptrace compat wrapper for fpu register access

[Andreas Schwab]

Michael Neuling <mikey at neuling.org> writes:

> So if you're looking fixing 32 bit apps ptracing 64 bit apps, does that
> mean we can get a single 32 bit GDB that'll ptrace both 64 and 32 bit
> apps?

Currently gdb only supports 32x64 debugging for the SPU.

>> @@ -263,7 +263,8 @@ long compat_arch_ptrace(struct task_struct *child, compat
> _long_t request,
>>  			ret = ptrace_put_reg(child, numReg, freg);
>>  		} else {
>>  			flush_fp_to_thread(child);
>> -			((unsigned int *)child->thread.regs)[index] = data;
>> +			((unsigned int *)child->thread.regs)
>> +				[FPRINDEX(index)] = data;
>
> This index is into the ptregs structure not the fpr.  I'm not sure the
> FPRINDEX macro is applicable here.

You're right, this hunk is bogus.  But indexing off thread.regs is
totally bogus as well.  I think what was intented is this:

@@ -263,7 +263,9 @@ long compat_arch_ptrace(struct task_stru
 			ret = ptrace_put_reg(child, numReg, freg);
 		} else {
 			flush_fp_to_thread(child);
-			((unsigned int *)child->thread.regs)[index] = data;
+			((unsigned int *)child->thread.fpr)
+				[TS_FPRWIDTH * (numReg - PT_FPR0) * 2 +
+				 index % 2] = data;
 			ret = 0;
 		}
 		break;

But gdb does not actually use PPC_PTRACE_POKEUSR_3264.

Andreas.

-- 
Andreas Schwab, schwab at linux-m68k.org
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