linux-mips
[Top] [All Lists]

Re: [PATCH] fix modpost segfault for 64bit mipsel kernel

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: [PATCH] fix modpost segfault for 64bit mipsel kernel
From: Thiemo Seufer <ths@networkno.de>
Date: Thu, 20 Apr 2006 17:23:19 +0100
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org, sam@ravnborg.org
In-reply-to: <20060421.010237.25910405.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20060417162742.GD28935@networkno.de> <20060419.112228.108306767.anemo@mba.ocn.ne.jp> <20060420001900.GC30806@networkno.de> <20060421.010237.25910405.anemo@mba.ocn.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.11+cvs20060403
Atsushi Nemoto wrote:
> On Thu, 20 Apr 2006 01:19:00 +0100, Thiemo Seufer <ths@networkno.de> wrote:
> > > +#define ELF64_MIPS_R_TYPE(i) \
> > > +  (((_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1 \
> > > +   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
> > > +            ).r_info_fields.r_type2 << 8) \
> > > +   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
> > > +            ).r_info_fields.r_type3 << 16) \
> > > +   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
> > > +            ).r_info_fields.r_ssym << 24))
> > 
> > Why is it the right thing to combine the type info into a 32bit word?
> 
> Well, I just take ELF64_MIPS_R_TYPE() from glibc source.

It is not more useful in glibc. :-)  Any use of the TYPE data will have
to take the MIPS64 specifics in account, and thus split it up again
into single characters.

> > It will never get used as such for MIPS ELF64. I would have expected
> > something like:
> > 
> > #define ELF64_MIPS_R_INFO(sym,ssym,t3,t2,t1)                \
> > {(                                                  \
> >     _Elf64_Mips_R_Info info = {                     \
> >             .r_sym = sym,                           \
> >             .r_ssym = ssym,                         \
> >             .r_type3 = t3,                          \
> >             .r_type2 = t2,                          \
> >             .r_type1 = t1,                          \
> >     }                                               \
> >     (Elf64_Xword)info;                              \
> > )}
> > 
> > without a corresponding ELF64_MIPS_R_TYPE, and then:
> > 
> >     if (hdr->e_ident[EI_CLASS] == ELFCLASS64
> >         && hdr->e_machine == EM_MIPS) {
> >             _Elf64_Mips_R_Info info = (_Elf64_Mips_R_Info)r.r_info;
> >             r.r_info = ELF64_MIPS_R_INFO(TO_NATIVE(info.r_sym),
> >                                          info.r_ssym, info.r_type3,
> >                                          info.r_type2, info.r_type1);
> >     }
> 
> Sorry, I can not see what you mean ... it just does byte-swap only
> r_sym part, doesn't it?  It is not enough because a position of r_sym
> in MIPS ELF64 r_info is different from standard ELF64 r_info.

But it does so for a _Elf64_Mips_R_Info struct, which already keeps
the position of its r_sym field endianness independent.


Thiemo

<Prev in Thread] Current Thread [Next in Thread>