On Thu, Feb 18, 2021 at 08:09:17PM +0300, Evgenii Shatokhin wrote: > Is there a way to allow probing of functions in .text.<something> ? > > Of course, one could place probes using absolute addresses of the functions > but that would be less convenient. > > This also affects many livepatch modules where the kernel code can be > compiled with -ffunction-sections and each function may end up in a separate > section .text.<function_name>. 'perf probe' cannot be used there, except > with the absolute addresses. > > Moreover, if FGKASLR patches are merged (https://lwn.net/Articles/832434/) > and the kernel is built with FGKASLR enabled, -ffunction-sections will be > used too. 'perf probe' will be unable to see the kernel functions then. A hack fix like the below would probably work, but as you pointed out, FGKASLR is going to be a problem. I suspect the proper fix is for perf to learn how to deal with multiple executable ELF sections. diff --git a/scripts/module.lds.S b/scripts/module.lds.S index 69b9b71a6a47..0c522a87f6ce 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -4,6 +4,10 @@ * combine them automatically. */ SECTIONS { + .text : { + *(.text) + *(.text.*) + } /DISCARD/ : { *(.discard) *(.discard.*)
