On Fri, May 24, 2019 at 6:58 PM Shane Peelar <lookatyouhac...@gmail.com> wrote: > > Great! Would you be willing to accept a patch that makes arch-x86_64.c > handle that condition like the other arches? >
yes certainly. > -Shane > > On Fri, May 24, 2019 at 12:27 PM Khem Raj <raj.k...@gmail.com> wrote: >> >> >> >> On 5/24/19 8:10 AM, Shane Peelar wrote: >> > I did some reading into the sources in other architectures. The closest >> > match, arch_i386.c, makes the write conditional as you say. >> > So do other arches, including |arch_arm.c, |arch_sh.c, |arch-mips.c, >> > |arch-s390.c, |arch-s390x.c, and |arch-ia64.c.|||||| >> > |||||| >> > |||||| >> > Notably, |||||||arch-cris.c||||||| has the same assert as >> > |||||||arch-x86_64.c||||||| instead of the conditional. >> > >> > The code roughly looks like follows:|||||||||||||| >> > |||||||||||||| >> > ||||||| >> > ||||||| >> > 1. Check for dso->info[DT_PLTGOT]. If it does not exist, return 0 >> > 2. Call addr_to_sec on dso->info[DT_PLTGOT], return 1 if error >> > 3. Look for the section named ".plt" in the ELF. >> > 4. If the section cannot be found, return 0 >> > 5. Otherwise, write the address of .plt + constant (dependent on arch) >> > to got[1]|||||||||||||| >> > |||||||||||||| >> > ||||||| >> > ||||||| >> > In |||||||arch-x86_64.c and arch-cris.c|||||||, step (4) above is an >> > assert:||||||| >> > >> > |||||||1. Check for dso->info[DT_PLTGOT]. If it does not exist, return 0 >> > 2. Call addr_to_sec on dso->info[DT_PLTGOT], return 1 if error >> > 3. Look for the section named ".plt" in the ELF. >> > 4. Assert that the section was found >> > 5. Write the address of .plt + constant (dependent on arch) to got[1] >> > >> > I tested out making the assert conditional and nothing seemed to break >> > at least. >> > ||||||| >> > ||||||| >> >> It seems ok to me. >> >> > >> > On Fri, May 24, 2019 at 12:08 AM Khem Raj <raj.k...@gmail.com >> > <mailto:raj.k...@gmail.com>> wrote: >> > >> > >> > >> > On 5/23/19 7:53 PM, Shane Peelar wrote: >> > > Any of them on the system pretty much, and yes they are also >> > built with >> > > -fno-plt. >> > >> > OK, I think its better to them conditionally check for .plt section, >> > can you describe more of whats going on when sections are checked. >> > >> > > >> > > On Thu, May 23, 2019 at 9:59 PM Khem Raj <raj.k...@gmail.com >> > <mailto:raj.k...@gmail.com> >> > > <mailto:raj.k...@gmail.com <mailto:raj.k...@gmail.com>>> wrote: >> > > >> > > >> > > >> > > On 5/23/19 8:05 AM, Shane Peelar wrote: >> > > > Hi Everyone @ the Yocto project, >> > > > >> > > > I'm Shane Peelar, a PhD Candidate at the University of >> > Windsor. >> > > > I'm writing to you about prelink-cross, as part of the >> > Yocto project. >> > > > Specifically, I'm looking at using it with executables >> > built using >> > > > `-fno-plt` under GCC. >> > > > I wasn't quite sure where to send this email to, so I >> > figured I'd >> > > try >> > > > here. If there's a better place to send this, please let >> > me know. >> > > > >> > > > Right now, prelink-cross seems to fail an assertion in >> > > arch-x86_64.c, >> > > > line 421, when >> > > > using it with an executable built with `-fno-plt`: >> > > > >> > > > ... >> > > > assert (i < dso->ehdr.e_shnum) >> > > > ... >> > > > >> > > > This snippet seems to be looking for the ".plt" section and, >> > > since it >> > > > can't find it, the assertion fires. This makes sense >> > because in >> > > > `-fno-plt` executables, the `.plt` section is missing >> > entirely. >> > > > I'm not an expert on ELF stuff, although I am learning >> > quickly. It >> > > > looks like >> > > > this code wants to write into GOT[1] the address of ".plt" >> > + 0x16 -- >> > > > since ".plt" doesn't >> > > > exist, does it make sense to just change this assert to an if >> > > statement >> > > > like so: >> > > > >> > > > ... >> > > > if (i < dso->ehdr.e_shnum) >> > > > { ... } >> > > > ... >> > > > >> > > > and skip over that part? Or is this a real error >> > condition for >> > > > prelink-cross and it really should not continue? The >> > executable in >> > > > question is also non-PIE, if that makes a difference. >> > > > >> > > >> > > what shared libs is this linking to ? are they also built with >> > > -fno-plt ? >> > > >> > > > Thanks for your time, >> > > > Shane >> > > > >> > > >> > -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto