On Tue, 22 Feb 2022, Jakub Jelinek wrote:
> Hi!
>
> On
> #define A(n) int foo1##n(void) { return 1##n; }
> #define B(n) A(n##0) A(n##1) A(n##2) A(n##3) A(n##4) A(n##5) A(n##6) A(n##7)
> A(n##8) A(n##9)
> #define C(n) B(n##0) B(n##1) B(n##2) B(n##3) B(n##4) B(n##5) B(n##6) B(n##7)
> B(n##8) B(n##9)
> #define D(n) C(n##0) C(n##1) C(n##2) C(n##3) C(n##4) C(n##5) C(n##6) C(n##7)
> C(n##8) C(n##9)
> #define E(n) D(n##0) D(n##1) D(n##2) D(n##3) D(n##4) D(n##5) D(n##6) D(n##7)
> D(n##8) D(n##9)
> E(0) E(1) E(2) D(30) D(31) C(320) C(321) C(322) C(323) C(324) C(325)
> B(3260) B(3261) B(3262) B(3263) A(32640) A(32641) A(32642)
> testcase with
> ./xgcc -B ./ -c -g -fpic -ffat-lto-objects -flto -O0 -o foo1.o foo1.c
> -ffunction-sections
> ./xgcc -B ./ -shared -g -fpic -flto -O0 -o foo1.so foo1.o
> /tmp/ccTW8mBm.debug.temp.o: file not recognized: file format not recognized
> (testcase too slow to be included into testsuite).
> The problem is clearly reported by readelf:
> readelf: foo1.o.debug.temp.o: Warning: Section 2 has an out of range sh_link
> value of 65321
> readelf: foo1.o.debug.temp.o: Warning: Section 5 has an out of range sh_link
> value of 65321
> readelf: foo1.o.debug.temp.o: Warning: Section 10 has an out of range sh_link
> value of 65323
> readelf: foo1.o.debug.temp.o: Warning: [ 2]: Link field (65321) should index
> a symtab section.
> readelf: foo1.o.debug.temp.o: Warning: [ 5]: Link field (65321) should index
> a symtab section.
> readelf: foo1.o.debug.temp.o: Warning: [10]: Link field (65323) should index
> a string section.
> because simple_object_elf_copy_lto_debug_sections doesn't adjust sh_info and
> sh_link fields in ElfNN_Shdr if they are in between SHN_{LO,HI}RESERVE
> inclusive. Not adjusting those is incorrect though, SHN_{LO,HI}RESERVE
> range is only relevant to the 16-bit fields, mainly st_shndx in ElfNN_Sym
> where if one needs >= SHN_LORESERVE section number, SHN_XINDEX should be
> used instead and .symtab_shndx section should contain the real section
> index, and in ElfNN_Ehdr e_shnum and e_shstrndx fields, where if >=
> SHN_LORESERVE value is needed it should put those into
> Shdr[0].sh_{size,link}. But, sh_{link,info} are 32-bit fields which can
> contain any section index.
>
> Note, as simple-object-elf.c mentions, binutils from 2.12 to 2.18 (so before
> 2011) used to mishandle the > 63.75K sections case and assumed there is a
> hole in between the sections, but what
> simple_object_elf_copy_lto_debug_sections does wouldn't help in that case
> for the debug temp object creation, we'd need to detect the case also in
> that routine and take it into account in the remapping etc. I think
> it is not worth it given that it is over 10 years, if somebody needs
> 63.75K or more sections, better use more recent binutils.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK. I suppose this also qualifies for backports?
Thanks,
Richard.
> 2022-02-22 Jakub Jelinek <ja...@redhat.com>
>
> PR lto/104617
> * simple-object-elf.c (simple_object_elf_match): Fix up URL
> in comment.
> (simple_object_elf_copy_lto_debug_sections): Remap sh_info and
> sh_link even if they are in the SHN_LORESERVE .. SHN_HIRESERVE
> range (inclusive).
>
> --- libiberty/simple-object-elf.c.jj 2022-01-11 23:11:23.967267993 +0100
> +++ libiberty/simple-object-elf.c 2022-02-21 20:37:12.815202845 +0100
> @@ -528,7 +528,7 @@ simple_object_elf_match (unsigned char h
> not handle objects with more than SHN_LORESERVE sections
> correctly. All large section indexes were offset by
> 0x100. There is more information at
> - http://sourceware.org/bugzilla/show_bug.cgi?id-5900 .
> + https://sourceware.org/PR5900 .
> Fortunately these object files are easy to detect, as the
> GNU binutils always put the section header string table
> near the end of the list of sections. Thus if the
> @@ -1559,17 +1559,13 @@ simple_object_elf_copy_lto_debug_section
> {
> sh_info = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
> shdr, sh_info, Elf_Word);
> - if (sh_info < SHN_LORESERVE
> - || sh_info > SHN_HIRESERVE)
> - sh_info = sh_map[sh_info];
> + sh_info = sh_map[sh_info];
> ELF_SET_FIELD (type_functions, ei_class, Shdr,
> shdr, sh_info, Elf_Word, sh_info);
> }
> sh_link = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
> shdr, sh_link, Elf_Word);
> - if (sh_link < SHN_LORESERVE
> - || sh_link > SHN_HIRESERVE)
> - sh_link = sh_map[sh_link];
> + sh_link = sh_map[sh_link];
> ELF_SET_FIELD (type_functions, ei_class, Shdr,
> shdr, sh_link, Elf_Word, sh_link);
> }
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
