From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jessica Yu <jeyu@kernel.org>, Nicolas Pitre <nico@fluxnic.net>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Masahiro Yamada <masahiroy@kernel.org>
Subject: [PATCH v2 1/4] export.h: make __ksymtab_strings per-symbol section
Date: Wed, 10 Mar 2021 00:17:34 +0900 [thread overview]
Message-ID: <20210309151737.345722-2-masahiroy@kernel.org> (raw)
In-Reply-To: <20210309151737.345722-1-masahiroy@kernel.org>
The export symbol tables are placed on own sections (__ksymtab*+<sym>)
and sorted by SORT (an alias of SORT_BY_NAME) because the module
subsystem uses the binary search for symbol resolution.
We did not have a good reason to do so for __ksymtab_strings, but
now I have.
To make CONFIG_TRIM_UNUSED_KSYMS work in one-pass, the linker needs
to trim unused strings of symbols and namespaces. To allow per-symbol
keep/drop choice, __ksymtab_strings must be placed on own sections.
This keeps the string unification introduced by commit ce2b617ce8cb
("export.h: reduce __ksymtab_strings string duplication by using "MS"
section flags").
For example, the empty namespaces share the same address.
$ nm -n vmlinux
[ snip ]
ffffffff8233b6aa r __kstrtabns_IO_APIC_get_PCI_irq_vector
ffffffff8233b6aa r __kstrtabns_I_BDEV
ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast
ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast_continue
ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast_usingDict
...
I confirmed no size change in vmlinux.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---
(no changes since v1)
include/asm-generic/export.h | 2 +-
include/asm-generic/vmlinux.lds.h | 2 +-
include/linux/export.h | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 07a36a874dca..e847f1fde367 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -39,7 +39,7 @@
__ksymtab_\name:
__put \val, __kstrtab_\name
.previous
- .section __ksymtab_strings,"aMS",%progbits,1
+ .section __ksymtab_strings+\name,"aMS",%progbits,1
__kstrtab_\name:
.asciz "\name"
.previous
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 0331d5d49551..6ce6dcabdccf 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -513,7 +513,7 @@
\
/* Kernel symbol table: strings */ \
__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
- *(__ksymtab_strings) \
+ *(__ksymtab_strings+*) \
} \
\
/* __*init sections */ \
diff --git a/include/linux/export.h b/include/linux/export.h
index 6271a5d9c988..01e6ab19b226 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -99,7 +99,7 @@ struct kernel_symbol {
extern const char __kstrtab_##sym[]; \
extern const char __kstrtabns_##sym[]; \
__CRC_SYMBOL(sym, sec); \
- asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \
+ asm(" .section \"__ksymtab_strings+" #sym "\",\"aMS\",%progbits,1\n" \
"__kstrtab_" #sym ": \n" \
" .asciz \"" #sym "\" \n" \
"__kstrtabns_" #sym ": \n" \
--
2.27.0
next prev parent reply other threads:[~2021-03-09 15:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 15:17 [PATCH v2 0/4] kbuild: build speed improvement of CONFIG_TRIM_UNUSED_KSYMS Masahiro Yamada
2021-03-09 15:17 ` Masahiro Yamada [this message]
2021-03-09 15:17 ` [PATCH v2 2/4] kbuild: separate out vmlinux.lds generation Masahiro Yamada
2021-03-09 15:17 ` [PATCH v2 3/4] kbuild: re-implement CONFIG_TRIM_UNUSED_KSYMS to make it work in one-pass Masahiro Yamada
2021-03-09 17:36 ` Nicolas Pitre
2021-03-09 18:11 ` Masahiro Yamada
2021-03-09 19:54 ` Nicolas Pitre
2021-03-09 20:11 ` Rasmus Villemoes
2021-03-09 20:45 ` Nicolas Pitre
2021-03-17 15:48 ` kernel test robot
2021-03-09 15:17 ` [PATCH v2 4/4] kbuild: remove guarding from TRIM_UNUSED_KSYMS Masahiro Yamada
2021-03-09 19:54 ` Linus Torvalds
2021-03-10 12:55 ` kernel test robot
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=20210309151737.345722-2-masahiroy@kernel.org \
--to=masahiroy@kernel.org \
--cc=hch@lst.de \
--cc=jeyu@kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nico@fluxnic.net \
--cc=torvalds@linux-foundation.org \
/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 NNTP newsgroup(s).