Hi Ying, On Tue, May 16, 2023 at 02:38:45PM +0800, Ying Huang wrote: > 在 2023/5/9 23:15, Mark Wielaard 写道: > > On Tue, 2023-04-11 at 16:12 +0800, Ying Huang wrote: > >> In mips64 little-endian, r_info consists of four byte fields(contains > >> three reloc types) and a 32-bit symbol index. In order to adapt > >> GELF_R_SYM and GELF_R_TYPE, need convert raw data to get correct symbol > >> index and type. > > Is there a spec that describes this? > > > references: > > https://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf > > Page40 && Page41
Thanks. Interesting. If possible please include this URL in a comment. > > I see you adjusted elf.h to include: > > > > +#define ELF64_MIPS_R_TYPE(i) ((i) & 0xff) > > +#define ELF64_MIPS_R_TYPE2(i) (((i) >> 8) & 0xff) > > +#define ELF64_MIPS_R_TYPE3(i) (((i) >> 16) & 0xff) > > > > And various new relocation types for MIPS variants. > > Our elf.h comes from the glibc project. Have you also submitted these > > changes to libc-al...@sourceware.org ? > Has submitted. > > https://sourceware.org/pipermail/libc-alpha/2023-May/148026.html > > https://sourceware.org/pipermail/libc-alpha/2023-May/148112.html Thanks. We'll sync them as soon as v3 lands. > Has tested on big/little endian machine with big/little endian > ELF file, all were OK. Could you post those ELF files somewhere? Maybe we can add some as test files? > > It feels like this is in the wrong place and doesn't take into account > > whether the program itself is running on a big or little endian > > machine. > > > > Maybe I am misunderstanding why this conversion is needed always. But I > > would have expected a specific conversion function for MIPS for > > ELF_T_REL and/or ELF_T_RELA (which are currently generic). > > 1.Considering that some people directly use the original data instead of > the interface function gelf_getrela; > > 2.Because there is only one parameter, so can not modify the macro > ELF64_R_TYPE； > > 3.If the mips interface function is added, other packages using libelf > will not be compatible with mips, and the place where gelf_getrela is used > need be modified. > > Where do you think is the most suitable place to do mips conversion? So for the convert_data case in elf_getdata.c I would expect a special conversion function being defined for ELF_T_REL and ELF_T_RELA. This normally comes from __elf_xfctstom. I realize now that cannot easily take an Elf of machine type. But I would expect to have the conversion be done by a new function that can be assigned to fp in convert_data: /* Get the conversion function. */ fp = __elf_xfctstom[eclass - 1][type]; I still don't fully understand the need of the code in elf_update. I assume that is needed in case the file was used with ELF_C_RDWR_MMAP? Cheers, Mark
