fix PPC floating point debug

The PPC architecture is unable to debug applications using hardware floating point, because it would not save the floating point registers.

After returning from the debugger, the contents of register was modified. This patch fix this bug.

Signed-off-by Stefani Seibold <[email protected]>

---
 traps.c |    6 ++++++
 1 file changed, 6 insertions(+)

arch/powerpc/kernel/traps.c renamed from arch/powerpc/kernel/traps.c.orig +6 -0

@@ -559,6 +559,8 @@ void instruction_breakpoint_exception(st
 		return;
 	if (debugger_iabr_match(regs))
 		return;
+	if (regs->msr & MSR_FP)
+		giveup_fpu(current);
 	_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 }
 

@@ -577,6 +579,8 @@ void __kprobes single_step_exception(str
 	if (debugger_sstep(regs))
 		return;
 
+	if (regs->msr & MSR_FP)
+		giveup_fpu(current);
 	_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
 }
 

@@ -834,6 +838,8 @@ void __kprobes program_check_exception(s
 			regs->nip += 4;
 			return;
 		}
+		if (regs->msr & MSR_FP)
+			giveup_fpu(current);
 		_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 		return;
 	}

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Quoted 5 lines

The PPC architecture is unable to debug applications using hardware floating point, because it would not save the floating point registers.

After returning from the debugger, the contents of register was modified. This patch fix this bug.

I'm not sure what problem you are trying to fix... debugging FP apps works just fine afaik. You don't need to flush the FP state into the thread when delivering the SIGTRAP. If you have a signal handler, that will be done for you by the signal code before laying out the signal frame. If you are using ptrace, you should be using the appropriate ptrace calls to retrieve the FP state and they should do the right thing to.