Re: [PATCH v3] elf: Set p_align to the minimum page size if possible

["H.J. Lu" <hjl.tools@gmail.com>]

On Fri, Jan 14, 2022 at 6:08 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 14.01.2022 15:02, H.J. Lu wrote:
> > On Fri, Jan 14, 2022 at 5:40 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>
> >> On 14.01.2022 14:03, H.J. Lu wrote:
> >>> On Fri, Jan 14, 2022 at 12:27 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>>>
> >>>> On 29.12.2021 20:39, H.J. Lu via Binutils wrote:
> >>>>> --- a/ld/testsuite/ld-elf/linux-x86.exp
> >>>>> +++ b/ld/testsuite/ld-elf/linux-x86.exp
> >>>>> @@ -185,6 +185,42 @@ run_ld_link_exec_tests [list \
> >>>>>       "" \
> >>>>>       "tmpdir/indirect-extern-access-2.so" \
> >>>>>      ] \
> >>>>> +    [list \
> >>>>> +     "Run p_align-1a without PIE" \
> >>>>> +     "$NOPIE_LDFLAGS" \
> >>>>> +     "" \
> >>>>> +     { p_align-1.c } \
> >>>>> +     "p_align-1a" \
> >>>>> +     "pass.out" \
> >>>>> +     "$NOPIE_CFLAGS" \
> >>>>> +    ] \
> >>>>> +    [list \
> >>>>> +     "Run p_align-1b with PIE" \
> >>>>> +     "-pie" \
> >>>>> +     "" \
> >>>>> +     { p_align-1.c } \
> >>>>> +     "p_align-1b" \
> >>>>> +     "pass.out" \
> >>>>> +     "-fpie" \
> >>>>> +    ] \
> >>>>> +    [list \
> >>>>> +     "Run p_align-1c with -Wl,-z,max-page-size=0x1000 without PIE" \
> >>>>> +     "$NOPIE_LDFLAGS -Wl,-z,max-page-size=0x1000" \
> >>>>> +     "" \
> >>>>> +     { p_align-1.c } \
> >>>>> +     "p_align-1c" \
> >>>>> +     "pass.out" \
> >>>>> +     "$NOPIE_CFLAGS" \
> >>>>> +    ] \
> >>>>> +    [list \
> >>>>> +     "Run p_align-1d with -Wl,-z,max-page-size=0x1000 with PIE" \
> >>>>> +     "-pie -Wl,-z,max-page-size=0x1000" \
> >>>>> +     "" \
> >>>>> +     { p_align-1.c } \
> >>>>> +     "p_align-1d" \
> >>>>> +     "pass.out" \
> >>>>> +     "-fpie" \
> >>>>> +    ] \
> >>>>>  ]
> >>>>
> >>>> The two PIE variants of this also fail for me on glibc 2.26. Looks
> >>>> like LOAD segments' alignment isn't being honored there, at least
> >>>> not if it's as big as it is here.
> >>>>
> >>>
> >>> The PIE alignment needs the kernel fix:
> >>>
> >>> commit ce81bb256a224259ab686742a6284930cbe4f1fa
> >>> Author: Chris Kennelly <ckennelly@google.com>
> >>> Date:   Thu Oct 15 20:12:32 2020 -0700
> >>>
> >>>     fs/binfmt_elf: use PT_LOAD p_align values for suitable start address
> >>
> >> Well, then the test needs to be skipped if that fix is not in place.
> >> After all you're testing binutils behavior here, not kernel or libc one.
> >> I'm running a variety of (largely up-to-date) kernels on all of my
> >> systems. But it looks like our kernel folks decided against backporting
> >> this particular change. And I don't think you expect people to remember
> >> to run the testsuite only on top of "certain" kernels?
> >
> > Care to submit a patch?
>
> I have no idea what to check for. I would really expect you to fix such
> an issue (or really two of them, considering the other problem) recently
> introduced by you.

What compiler are you using on the broken kernel?

-- 
H.J.