From: Xi Ruoyao <xry111@xry111.site>
To: liuzhensong <liuzhensong@loongson.cn>, binutils@sourceware.org
Cc: Chenghua Xu <xuchenghua@loongson.cn>,
Lulu Cheng <chenglulu@loongson.cn>, Wang Xuerui <i@xen0n.name>
Subject: Re: [PATCH 2/2] LoongArch: Fix R_LARCH_IRELATIVE insertion after elf_link_sort_relocs
Date: Sun, 18 Sep 2022 17:58:03 +0800 [thread overview]
Message-ID: <793d0e700362794e814ad67c78aa532458202aef.camel@xry111.site> (raw)
In-Reply-To: <f262b6b355809d1d6b757f90b792bcab6ab71872.camel@xry111.site>
On Sat, 2022-09-17 at 04:11 +0800, Xi Ruoyao via Binutils wrote:
> The problem is loongarch_elf_finish_dynamic_symbol runs after
> elf_link_sort_relocs. elf_link_sort_relocs basically does:
>
> (pseudo code)
>
> buffer = []
> for section in {input of .rela.dyn}
> buffer += (section.content) as [RELA]
>
> buffer.sort_by(some_comparator)
>
> buffer = buffer as [byte]
> for section in {input of .rela.dyn}
> section.content = buffer[..section.content.len()]
> buffer = buffer[section.content.len()..]
>
> So a "slot" in relplt->contents can end up elsewhere. You can read the
> code of elf_link_sort_relocs to see it...
>
> I can try to write a test case for this, but it's 04:00 AM now so I'd do
> it after a sleep...
Take this as an example, note that the R_LARCH_IRELATIVE relocation is
missing with -z combreloc:
$ cat b1.s
.text
.align 2
.local ifunc
.type ifunc, @gnu_indirect_function
.set ifunc, resolver
resolver:
la.local $a0, impl
jr $ra
impl:
li.w $a0, 42
jr $ra
.global test
.type test, @function
test:
move $s0, $ra
bl ifunc
xori $a0, $a0, 42
jr $s0
.data
.global ptr
.type ptr, @object
ptr:
.dword test
$ gas/as-new b1.s -o b1.o
$ ld/ld-new -shared b1.o # "-z combreloc" is the default
$ readelf -r a.out
Relocation section '.rela.dyn' at offset 0x1f0 contains 2 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000000 000000000000 R_LARCH_NONE 8018
000000008000 000400000002 R_LARCH_64 0000000000000264 test + 0
$ ld/ld-new -shared b1.o -z nocombreloc
$ readelf -r a.out
Relocation section '.rela.data' at offset 0x1f0 contains 1 entry:
Offset Info Type Sym. Value Sym. Name + Addend
000000008000 000400000002 R_LARCH_64 0000000000000264 test + 0
Relocation section '.rela.got' at offset 0x208 contains 1 entry:
Offset Info Type Sym. Value Sym. Name + Addend
000000008018 00000000000c R_LARCH_IRELATIVE 250
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
prev parent reply other threads:[~2022-09-18 9:58 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-13 15:44 [PATCH 0/2] LoongArch: Fix two bugs breaking IFUNC in static PIE Xi Ruoyao
2022-09-13 15:44 ` [PATCH 1/2] LoongArch: Avoid heap-buffer-overflow in loongarch_elf_relocate_section Xi Ruoyao
2022-09-14 8:57 ` liuzhensong
2022-09-14 10:15 ` Xi Ruoyao
2022-09-14 11:15 ` Xi Ruoyao
2022-09-15 1:47 ` liuzhensong
2022-09-15 2:56 ` Xi Ruoyao
2022-09-15 3:54 ` liuzhensong
2022-09-15 6:13 ` Xi Ruoyao
2022-09-13 15:44 ` [PATCH 2/2] LoongArch: Fix R_LARCH_IRELATIVE insertion after elf_link_sort_relocs Xi Ruoyao
2022-09-15 13:03 ` liuzhensong
2022-09-16 20:11 ` Xi Ruoyao
2022-09-18 9:58 ` Xi Ruoyao [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=793d0e700362794e814ad67c78aa532458202aef.camel@xry111.site \
--to=xry111@xry111.site \
--cc=binutils@sourceware.org \
--cc=chenglulu@loongson.cn \
--cc=i@xen0n.name \
--cc=liuzhensong@loongson.cn \
--cc=xuchenghua@loongson.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).