Re: [PATCHv2] ftrace: Show all functions with addresses in available_filter_functions_addrs
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2023-06-12 02:58:02
Also in:
bpf, lkml
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2023-06-12 02:58:02
Also in:
bpf, lkml
On Sun, 11 Jun 2023 22:54:07 -0400 Steven Rostedt [off-list ref] wrote:
quoted
Also, if there are multiple same static functions with different addresses, user space might need to check dwarf or proposed BTF_KIND_KFUNC (which encode kallsyms addresses) to find whether entry in available_filter_functions_addrs to be used. But addresses may not match. How this issue could be resolved?Easy, you use the address between two other addresses in kallsyms. The address is still in the function. The addresses in kallsyms is the starting address, but there's cases that the patch location is not at the start.
Not to mention, you can still use the kallsyms address. If you did the work to find it, then use it (it may not be as efficient as I mentioned before). That's basically what is done today (so I am told), and this patch was to create a file where you don't need to look up kallsyms when you know which function to use. The functions are sorted by address, so if you know of a unique function near the duplicate, you just find the duplicate that's near the unique function name. -- Steve