Messages in this thread | | | Date | Thu, 26 Mar 2020 17:06:50 +0100 | From | Peter Zijlstra <> | Subject | Re: [RESEND][PATCH v3 10/17] x86/static_call: Add inline static call implementation for x86-64 |
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On Tue, Mar 24, 2020 at 02:56:13PM +0100, Peter Zijlstra wrote: > From: Josh Poimboeuf <jpoimboe@redhat.com> > > Add the inline static call implementation for x86-64. The generated code > is identical to the out-of-line case, except we move the trampoline into > it's own section. > > Then objtool uses the trampoline section to detect all the call sites, > which it writes into the .static_call_sites section. > > During boot (and module init), the call sites are patched to call > directly into the destination function. The temporary trampoline is > then no longer used.
> +static int read_static_call_tramps(struct objtool_file *file) > +{ > + struct section *sec, *sc_sec = find_section_by_name(file->elf, ".static_call.text"); > + struct symbol *func; > + > + for_each_sec(file, sec) { > + list_for_each_entry(func, &sec->symbol_list, list) { > + if (func->sec == sc_sec) > + func->static_call_tramp = true; > + } > + } > + > + return 0; > +}
While talking Boris through this stuff, I just realized that if you use a static_call object defined in another translation-unit, IOW. the:
STATIC_CALL_TRAMP(name)(...);
call is an external call, the above objtool rule will not detect it and it'll stay using the trampoline...
Back to using a naming prefix I suppose.
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