[PATCH 1/2] powerpc/ftrace: Separate the heuristics for checking call sites

[Michael Ellerman]

Madhavan Srinivasan <maddy at linux.vnet.ibm.com> writes:

> On Tuesday 19 July 2016 10:18 AM, Michael Ellerman wrote:
>> In __ftrace_make_nop() (the 64-bit version), we have code to deal with
>> two ftrace ABIs. There is the original ABI, which looks mostly like a
>> function call, and then the mprofile-kernel ABI which is just a branch.
>>
...
>> diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
>> index 7af6c4de044b..438442dac44c 100644
>> --- a/arch/powerpc/kernel/ftrace.c
>> +++ b/arch/powerpc/kernel/ftrace.c
>> @@ -144,6 +144,21 @@ __ftrace_make_nop(struct module *mod,
>>   		return -EINVAL;
>>   	}
>>   
>> +#ifdef CC_USING_MPROFILE_KERNEL
>> +	/* When using -mkernel_profile there is no load to jump over */
>> +	pop = PPC_INST_NOP;
>> +
>> +	if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
>> +		pr_err("Fetching instruction at %lx failed.\n", ip - 4);
>> +		return -EFAULT;
>> +	}
>> +
>> +	/* We expect either a mlfr r0, or a std r0, LRSAVE(r1) */
>
> nit..  "mflr" and not "mlfr"

Yep, copied from the old comment, but I'll fix it up. Thanks.

cheers