On Thu, 26 Dec 2024 19:35:18 -0800 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 26 Dec 2024 at 13:49, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > > But then, when the linker removes these functions because they were > > overridden, the code does not disappear, leaving the pointers in the > > __mcount_loc locations. > > Btw, does this actually happen when the compiler does the mcount thing for us? Yes. I believe the issue is that the mcount_loc is created during the compile phase, and it just points to the call to fentry/mcount. The linker phase doesn't remove the code, just the symbols that are overridden. That means the pointer to the fentry/mcount calls still point to the same locations, as the code is still there. I even sent an email about this to the gcc folks, and Peter responded basically explaining the above. https://lore.kernel.org/all/20241014210841.5a4764de@xxxxxxxxxxxxxxxxxx/ -- Steve
