[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 1/6] symbols: add minimal self-test
On 13.03.2025 16:44, Andrew Cooper wrote: > On 13/03/2025 3:39 pm, Jan Beulich wrote: >> On 13.03.2025 16:35, Andrew Cooper wrote: >>> On 13/03/2025 1:52 pm, Jan Beulich wrote: >>>> ... before making changes to the involved logic. >>>> >>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> >>>> --- >>>> With this FAST_SYMBOL_LOOKUP may make sense to permit enabling even >>>> when LIVEPATCH=n. Thoughts? (In this case "symbols: centralize and re- >>>> arrange $(all_symbols) calculation" would want pulling ahead.) >>>> >>>> --- a/xen/common/symbols.c >>>> +++ b/xen/common/symbols.c >>>> @@ -260,6 +260,41 @@ unsigned long symbols_lookup_by_name(con >>>> return 0; >>>> } >>>> >>>> +#ifdef CONFIG_SELF_TESTS >>>> + >>>> +static void __init test_lookup(unsigned long addr, const char *expected) >>>> +{ >>>> + char buf[KSYM_NAME_LEN + 1]; >>>> + const char *name, *symname; >>>> + unsigned long size, offs; >>>> + >>>> + name = symbols_lookup(addr, &size, &offs, buf); >>>> + if ( !name ) >>>> + panic("%s: address not found\n", expected); >>>> + if ( offs ) >>>> + panic("%s: non-zero offset (%#lx) unexpected\n", expected, offs); >>>> + >>>> + /* Cope with static symbols, where varying file names/paths may be >>>> used. */ >>>> + symname = strchr(name, '#'); >>>> + symname = symname ? symname + 1 : name; >>>> + if ( strcmp(symname, expected) ) >>>> + panic("%s: unexpected symbol name: '%s'\n", expected, symname); >>>> + >>>> + offs = symbols_lookup_by_name(name); >>>> + if ( offs != addr ) >>>> + panic("%s: address %#lx unexpected; wanted %#lx\n", >>>> + expected, offs, addr); >>>> +} >>>> + >>>> +static void __init __constructor test_symbols(void) >>>> +{ >>>> + /* Be sure to only try this for cf_check functions. */ >>> I'm very happy to see the take-up of SELF_TESTs. Although I probably >>> ought to tie it into a Kconfig option to make the errors non-fatal, >>> which I've been meaning to do for a bit. >>> >>> One question though. cf_check is an x86-ism, even if it leaks out into >>> common code. >>> >>> I think you mean "functions emitted into the final image"? If so, I >>> don't think this is relevant then, because ... >>> >>>> + test_lookup((unsigned long)dump_execstate, "dump_execstate"); >>>> + test_lookup((unsigned long)test_symbols, __func__); >>> ... taking the function address here forces it to be emitted even if it >>> would otherwise have been inlined. >> No, I really mean cf_check. If we took the address of a non-cf_check >> function, the special gcc13 build's checking would trigger, aiui. > > It's GCC-11 sadly. cf_check is part of the function type, and triggers > when a function type check would be relevant. Just casing to an integer > won't trigger it, I don't think. Is there a way to double check? I'd be happy to drop that comment (and use some other, maybe less random function), but I don't have a compiler available that includes that patch. Jan
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