[PATCH -tip tracing/kprobes] Powerpc port of the kprobe-based event tracer.

[Wenji Huang]

Hi,

> +#define kernel_stack_pointer(regs) ((regs)->gpr[1])
> +
> +/**
> + * regs_get_register() - get register value from its offset
> + * @regs:	   pt_regs from which register value is gotten
> + * @offset:    offset number of the register.
> + *
> + * regs_get_register returns the value of a register whose offset from @regs
> + * is @offset. The @offset is the offset of the register in struct pt_regs.

"is @offset." seems be redundant.
> + * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
> + */
> +static inline unsigned long regs_get_register(struct pt_regs *regs,

[...]
> + * regs_within_kernel_stack() - check the address in the stack
> + * @regs:      pt_regs which contains kernel stack pointer.
> + * @addr:      address which is checked.
> + *
> + * regs_within_kenel_stack() checks @addr is within the kernel stack page(s).
> + * If @addr is within the kernel stack, it returns true. If not, returns false.

s/regs_within_kenel_stack/regs_within_kernel_stack/
The return type function is declared as int.
> + */
> +
> +static inline int regs_within_kernel_stack(struct pt_regs *regs,
> +						unsigned long addr)
> +{
> +	return ((addr & ~(THREAD_SIZE - 1))  ==
> +		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
> +}
> +
> +/**
> + * regs_get_kernel_stack_nth() - get Nth entry of the stack
> + * @regs:	pt_regs which contains kernel stack pointer.
> + * @n:		stack entry number.
> + *
> + * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
> + * is specifined by @regs. If the @n th entry is NOT in the kernel stack,
> + * this returns 0.

s/specifined/specified/
> + */
> +static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
> +						      unsigned int n)
> +{
> +	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
> +	addr += n;
> +	if (regs_within_kernel_stack(regs, (unsigned long)addr))
> +		return *addr;
> +	else
> +		return 0;
> +}
> +
> +
> +/* Get Nth argument at function call */
> +extern unsigned long regs_get_argument_nth(struct pt_regs *regs,
> +						unsigned int n);
> +

Maybe to put extern declaration at the very beginning is better.
>  /*
>   * These are defined as per linux/ptrace.h, which see.
>   */
[...]

Regards,
Wenji