Re: [Qemu-devel] Patch to fix mapping of elf pheaders specifying both .data and .bss segments

[Max Filippov <jcmvbkbc@gmail.com>]

Hello.

> On Thu, Aug 06, 2009 at 03:41:02PM -0700, Kai Backman wrote:
> > On Thu, Jun 18, 2009 at 11:57 AM, Riku Voipio<riku.voipio@iki.fi> wrote:
> > > The patch attached is totally messed up thou.
> > 
> > Sorry for the delay. I was vacationing in Finland (incidentally)..
> > 
> > To restart the thread, I've re-attached the patch.
> 
> I see Max Filippov has touched the same function for possibly the same
> issue?
> 
> http://lists.gnu.org/archive/html/qemu-devel/2009-07/msg00902.html
> 

You're right, the same issue. But the patch doesn't fix it for me: elf_interpreter mentioned in the last
hunk is always set to "/lib/ld.so.1". Having this condition removed it works perfectly.

> > diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> > index 190ad14..e4e75d5 100644
> > --- a/linux-user/elfload.c
> > +++ b/linux-user/elfload.c
> > @@ -1211,7 +1211,7 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
> >      abi_ulong mapped_addr;
> >      struct elf_phdr * elf_ppnt;
> >      struct elf_phdr *elf_phdata;
> > -    abi_ulong elf_bss, k, elf_brk;
> > +    abi_ulong elf_bss, last_bss, mapped_bss, k, elf_brk;
> >      int retval;
> >      char * elf_interpreter;
> >      abi_ulong elf_entry, interp_load_addr = 0;
> > @@ -1271,6 +1271,7 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
> >      elf_ppnt = elf_phdata;
> >  
> >      elf_bss = 0;
> > +    last_bss = 0;
> >      elf_brk = 0;
> >  
> >  
> > @@ -1495,12 +1496,24 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
> >          k = elf_ppnt->p_vaddr + elf_ppnt->p_filesz;
> >          if (k > elf_bss)
> >              elf_bss = k;
> > +        k = elf_ppnt->p_vaddr + elf_ppnt->p_memsz;
> > +        if (k > last_bss)
> > +            last_bss = k;
> >          if ((elf_ppnt->p_flags & PF_X) && end_code <  k)
> >              end_code = k;
> >          if (end_data < k)
> >              end_data = k;
> >          k = elf_ppnt->p_vaddr + elf_ppnt->p_memsz;
> >          if (k > elf_brk) elf_brk = k;
> > +        if (!elf_interpreter && last_bss > elf_bss) {
> > +      	    padzero(elf_bss, last_bss);
> > +	    mapped_bss = TARGET_ELF_PAGESTART(elf_bss + qemu_host_page_size - 1);
> > +
> > +	    /* Map the last of the bss segment */
> > +            target_mmap(load_bias + mapped_bss, last_bss-mapped_bss,
> > +                        PROT_READ|PROT_WRITE|PROT_EXEC,
> > +                        MAP_FIXED|MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
> > +        }
> >      }
> >  
> >      elf_entry += load_bias;
> 
> 

Thanks.
-- Max