From: Florian Weimer <fweimer@redhat.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Fangrui Song <i@maskray.me>, Binutils <binutils@sourceware.org>
Subject: Re: [PATCH] elf: Set p_align to the common page size if possible
Date: Mon, 20 Dec 2021 19:51:17 +0100 [thread overview]
Message-ID: <87bl1bf6u2.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <CAMe9rOqCdoZnfYo+fzzgFbUs6wvAoJX8fJNSgz_BC2tTcg4+Yg@mail.gmail.com> (H. J. Lu's message of "Mon, 20 Dec 2021 10:39:40 -0800")
* H. J. Lu:
> We need to set larger p_align > sh_addralign for huge page executables.
> My current algorithm to decide if p_align should be used as the maximum
> page size for objcopy is
>
> static bool
> elf_is_p_align_valid (bfd *abfd)
> {
> unsigned int i;
> Elf_Internal_Phdr *segment;
> unsigned int num_segments;
> const struct elf_backend_data *bed = get_elf_backend_data (abfd);
> bfd_size_type maxpagesize = bed->maxpagesize;
> bfd_size_type commonpagesize = bed->commonpagesize;
>
> if (commonpagesize == maxpagesize)
> return true;
>
> /* When the common page size != the maximum page size, p_align may
> be set to the common page size while segments are aligned to
> the maximum page size. In this case, the input p_align will be
> ignored and the maximum page size will be used to align the output
> segments. */
> segment = elf_tdata (abfd)->phdr;
> num_segments = elf_elfheader (abfd)->e_phnum;
> for (i = 0; i < num_segments; i++, segment++)
> if (segment->p_type == PT_LOAD
> && (segment->p_align != commonpagesize
> || vma_page_aligned_bias (segment->p_vaddr,
> segment->p_offset,
> maxpagesize) != 0))
> return true;
>
> return false;
> }
>
> It should cover all cases.
Will this switch from 64K to 4K on POWER and AArch64? I think this will
then produce binaries which cannot be loaded by current glibc in all
cases:
PT_LOAD p_align check is too strict
<https://sourceware.org/bugzilla/show_bug.cgi?id=28688>
Thanks,
Florian
next prev parent reply other threads:[~2021-12-20 18:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-15 16:32 H.J. Lu
2021-12-16 8:52 ` Fangrui Song
2021-12-16 14:33 ` H.J. Lu
2021-12-20 16:36 ` Florian Weimer
2021-12-20 18:39 ` H.J. Lu
2021-12-20 18:51 ` Florian Weimer [this message]
2021-12-20 18:59 ` H.J. Lu
2021-12-20 19:25 ` Florian Weimer
2021-12-20 19:31 ` H.J. Lu
2021-12-20 19:51 ` Florian Weimer
2021-12-20 15:50 ` H.J. Lu
2021-12-22 8:57 ` Alan Modra
2021-12-22 14:38 ` [PATCH v2] elf: Set p_align to the minimum " H.J. Lu
2021-12-25 1:03 ` Alan Modra
2021-12-25 2:50 ` H.J. Lu
2021-12-25 3:04 ` Alan Modra
2021-12-25 3:08 ` H.J. Lu
2021-12-25 3:58 ` Alan Modra
[not found] ` <f64b9fb3-7d2d-7ff3-a8f6-795292af6744@redhat.com>
[not found] ` <CAMe9rOrvGXXEJAESEgTbhgQJee__Ak9+OvFwzWa0Nxv+m+OjLg@mail.gmail.com>
2022-01-05 10:17 ` [PATCH] elf: Set p_align to the common " Nick Clifton
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