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static_call: Add inline static call infrastructure

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Add infrastructure for an arch-specific CONFIG_HAVE_STATIC_CALL_INLINE
option, which is a faster version of CONFIG_HAVE_STATIC_CALL.  At
runtime, the static call sites are patched directly, rather than using
the out-of-line trampolines.

Compared to out-of-line static calls, the performance benefits are more
modest, but still measurable.  Steven Rostedt did some tracepoint
measurements:

  https://lkml.kernel.org/r/20181126155405.72b4f718@gandalf.local.home

This code is heavily inspired by the jump label code (aka "static
jumps"), as some of the concepts are very similar.

For more details, see the comments in include/linux/static_call.h.

[peterz: simplified interface; merged trampolines]

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.684334440@infradead.org
This commit is contained in:
Josh Poimboeuf 2020-08-18 15:57:42 +02:00 • committed by Ingo Molnar
parent 115284d89a
commit 9183c3f9ed
8 changed files with 373 additions and 1 deletions
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5
kernel/module.c
View file

@ -3274,6 +3274,11 @@ static int find_module_sections(struct module *mod, struct load_info *info)
mod->kprobe_blacklist = section_objs(info, "_kprobe_blacklist",
sizeof(unsigned long),
&mod->num_kprobe_blacklist);
#endif
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
mod->static_call_sites = section_objs(info, ".static_call_sites",
sizeof(*mod->static_call_sites),
&mod->num_static_call_sites);
#endif
mod->extable = section_objs(info, "__ex_table",
sizeof(*mod->extable), &mod->num_exentries);