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

[Jan Beulich]

On 14.01.2022 15:14, H.J. Lu wrote:
> 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?

gcc 7.4.1

No idea how that matters, though.

Jan