Messages in this thread | | | Date | Fri, 6 May 2022 11:45:36 +0200 | From | Geert Stappers <> | Subject | Re: [PATCH v1 3/3] kallsyms: increase maximum kernel symbol length to 512 |
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On Thu, May 05, 2022 at 09:16:45PM +0200, Miguel Ojeda wrote: > > generates a symbol of length 96 when using the upcoming v0 mangling scheme: > > _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method > > At the moment, Rust symbols may reach up to 300 in length. > Setting 512 as the maximum seems like a reasonable choice to > keep some headroom. > > diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h > index ce1bd2fbf23e..e5ad6e31697d 100644 > --- a/include/linux/kallsyms.h > +++ b/include/linux/kallsyms.h > @@ -15,7 +15,7 @@ > > #include <asm/sections.h> > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512
multiplication factor is four
> --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, > * we use the smallest/strictest upper bound possible (56, based on > * the current definition of MODULE_NAME_LEN) to prevent overflows. > */ > - BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); > + BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512);
factor four
> @@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, > > /* Format: .klp.sym.sym_objname.sym_name,sympos */ > cnt = sscanf(strtab + sym->st_name, > - ".klp.sym.%55[^.].%127[^,],%lu", > + ".klp.sym.%55[^.].%511[^,],%lu",
4 * ( 127 + 1 ) = 511 + 1
> --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -30,10 +30,10 @@ > #define _stringify_1(x) #x > #define _stringify(x) _stringify_1(x) > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512
factor four
> --- a/tools/include/linux/kallsyms.h > +++ b/tools/include/linux/kallsyms.h > @@ -6,7 +6,7 @@ > #include <stdio.h> > #include <unistd.h> > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512
factor four
> --- a/tools/lib/perf/include/perf/event.h > +++ b/tools/lib/perf/include/perf/event.h > @@ -95,7 +95,7 @@ struct perf_record_throttle { > }; > > #ifndef KSYM_NAME_LEN > -#define KSYM_NAME_LEN 256 > +#define KSYM_NAME_LEN 512
Here is the multiplication factor two.
> --- a/tools/lib/symbol/kallsyms.h > +++ b/tools/lib/symbol/kallsyms.h > @@ -7,7 +7,7 @@ > #include <linux/types.h> > > #ifndef KSYM_NAME_LEN > -#define KSYM_NAME_LEN 256 > +#define KSYM_NAME_LEN 512
Another "factor two"
It feels good to unify all the KSYM_NAME_LEN to 512.
Thing that feels less good is doubling 256 versus quadrupling 128.
I felt the need to report that.
Feel free to ignore this remark.
Groeten Geert Stappers -- Silence is hard to parse
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