| Message ID | a556439c-b652-4789-bbdd-6d6402b2a124@suse.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | symbols: assorted adjustments | expand |
On 13/03/2025 1:52 pm, Jan Beulich wrote: > ... before making changes to the involved logic. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> > --- > 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. ~Andrew
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@suse.com> >> --- >> 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. Jan
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@suse.com> >>> --- >>> 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. ~Andrew
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@suse.com> >>>> --- >>>> 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
--- 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. */ + test_lookup((unsigned long)dump_execstate, "dump_execstate"); + test_lookup((unsigned long)test_symbols, __func__); +} + +#endif /* CONFIG_SELF_TESTS */ + /* * Local variables: * mode: C
... before making changes to the involved logic. Signed-off-by: Jan Beulich <jbeulich@suse.com> --- 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.)