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

[Jan Beulich]

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.

Jan