Re: [PATCH v4 3/9] bpf/btf: Add a function to search a member of a struct/union

[Steven Rostedt]

On Tue, 1 Aug 2023 11:20:36 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> The solution was to come up with ftrace_regs, which just means it has all
> the registers to extract the arguments of a function and nothing more. Most

This isn't 100% true. The ftrace_regs may hold a fully filled pt_regs. As
the FTRACE_WITH_REGS callbacks still get passed a ftrace_regs pointer. They
will do:

	void callback(..., struct ftrace_regs *fregs) {
		struct pt_regs *regs = ftrace_get_regs(fregs);


Where ftrace_get_regs() will return the pt_regs only if it is fully filled.
If it is not, then it returns NULL. This was what the x86 maintainers
agreed with.

-- Steve


> implementations just have a partially filled pt_regs within it, but an API
> needs to be used to get to the argument values.