From: Matthias Maennich <maennich@google.com>
To: linux-kernel@vger.kernel.org, maco@android.com
Cc: kernel-team@android.com, maennich@google.com, arnd@arndb.de,
geert@linux-m68k.org, gregkh@linuxfoundation.org, hpa@zytor.com,
jeyu@kernel.org, joel@joelfernandes.org,
kstewart@linuxfoundation.org, linux-arch@vger.kernel.org,
linux-kbuild@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
linux-modules@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-usb@vger.kernel.org, lucas.de.marchi@gmail.com,
maco@google.com, michal.lkml@markovi.net, mingo@redhat.com,
oneukum@suse.com, pombredanne@nexb.com, sam@ravnborg.org,
sboyd@codeaurora.org, sspatil@google.com,
stern@rowland.harvard.edu, tglx@linutronix.de,
usb-storage@lists.one-eyed-alien.net, x86@kernel.org,
yamada.masahiro@socionext.com,
Andrew Morton <akpm@linux-foundation.org>,
Nicolas Pitre <nico@fluxnic.net>,
Michael Ellerman <mpe@ellerman.id.au>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: [PATCH v2 02/10] export: explicitly align struct kernel_symbol
Date: Tue, 13 Aug 2019 13:16:59 +0100 [thread overview]
Message-ID: <20190813121733.52480-3-maennich@google.com> (raw)
In-Reply-To: <20190813121733.52480-1-maennich@google.com>
This change allows growing struct kernel_symbol without wasting bytes to
alignment. It also concretized the alignment of ksymtab entries if
relative references are used for ksymtab entries.
struct kernel_symbol was already implicitly being aligned to the word
size, except on x86_64 and m68k, where it is aligned to 16 and 2 bytes,
respectively.
As far as I can tell there is no requirement for aligning struct
kernel_symbol to 16 bytes on x86_64, but gcc aligns structs to their
size, and the linker aligns the custom __ksymtab sections to the largest
data type contained within, so setting KSYM_ALIGN to 16 was necessary to
stay consistent with the code generated for non-ASM EXPORT_SYMBOL(). Now
that non-ASM EXPORT_SYMBOL() explicitly aligns to word size (8),
KSYM_ALIGN is no longer necessary.
In case of relative references, the alignment has been changed
accordingly to not waste space when adding new struct members.
As for m68k, struct kernel_symbol is aligned to 2 bytes even though the
structure itself is 8 bytes; using a 4-byte alignment shouldn't hurt.
I manually verified the output of the __ksymtab sections didn't change
on x86, x86_64, arm, arm64 and m68k. As expected, the section contents
didn't change, and the ELF section alignment only changed on x86_64 and
m68k. Feedback from other archs more than welcome.
Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Matthias Maennich <maennich@google.com>
---
arch/m68k/include/asm/export.h | 1 -
include/asm-generic/export.h | 8 +++-----
include/linux/export.h | 3 ++-
3 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/arch/m68k/include/asm/export.h b/arch/m68k/include/asm/export.h
index 0af20f48bd07..b53008b67ce1 100644
--- a/arch/m68k/include/asm/export.h
+++ b/arch/m68k/include/asm/export.h
@@ -1,3 +1,2 @@
-#define KSYM_ALIGN 2
#define KCRC_ALIGN 2
#include <asm-generic/export.h>
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 294d6ae785d4..63f54907317b 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -4,15 +4,13 @@
#ifndef KSYM_FUNC
#define KSYM_FUNC(x) x
#endif
-#ifdef CONFIG_64BIT
-#ifndef KSYM_ALIGN
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define KSYM_ALIGN 4
+#elif defined(CONFIG_64BIT)
#define KSYM_ALIGN 8
-#endif
#else
-#ifndef KSYM_ALIGN
#define KSYM_ALIGN 4
#endif
-#endif
#ifndef KCRC_ALIGN
#define KCRC_ALIGN 4
#endif
diff --git a/include/linux/export.h b/include/linux/export.h
index fd8711ed9ac4..28a4d2150689 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -52,7 +52,7 @@ extern struct module __this_module;
#define __KSYMTAB_ENTRY(sym, sec) \
__ADDRESSABLE(sym) \
asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
- " .balign 8 \n" \
+ " .balign 4 \n" \
"__ksymtab_" #sym ": \n" \
" .long " #sym "- . \n" \
" .long __kstrtab_" #sym "- . \n" \
@@ -66,6 +66,7 @@ struct kernel_symbol {
#define __KSYMTAB_ENTRY(sym, sec) \
static const struct kernel_symbol __ksymtab_##sym \
__attribute__((section("___ksymtab" sec "+" #sym), used)) \
+ __aligned(sizeof(void *)) \
= { (unsigned long)&sym, __kstrtab_##sym }
struct kernel_symbol {
--
2.23.0.rc1.153.gdeed80330f-goog
next prev parent reply other threads:[~2019-08-13 12:19 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180716122125.175792-1-maco@android.com>
2019-08-13 12:16 ` [PATCH v2 0/10] Symbol namespaces - RFC Matthias Maennich
2019-08-13 12:16 ` [PATCH v2 01/10] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-13 12:40 ` Greg KH
2019-08-13 12:16 ` Matthias Maennich [this message]
2019-08-13 12:41 ` [PATCH v2 02/10] export: explicitly align struct kernel_symbol Greg KH
2019-08-13 12:17 ` [PATCH v2 03/10] module: add support for symbol namespaces Matthias Maennich
2019-08-13 15:26 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 04/10] modpost: " Matthias Maennich
2019-08-13 15:27 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-13 18:17 ` Greg KH
2019-08-13 20:15 ` Saravana Kannan
2019-08-14 12:54 ` Matthias Maennich
2019-08-14 17:34 ` Saravana Kannan
2019-08-13 12:17 ` [PATCH v2 06/10] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-13 18:16 ` Greg KH
2019-08-13 18:16 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 07/10] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-13 18:21 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 08/10] scripts: Coccinelle script for " Matthias Maennich
2019-08-13 12:31 ` Julia Lawall
2019-08-13 12:44 ` Greg KH
2019-08-14 6:36 ` [Cocci] " Himanshu Jha
2019-08-14 8:03 ` Matthias Maennich
2019-08-14 12:00 ` [v2 " Markus Elfring
2019-08-15 13:50 ` Markus Elfring
2019-08-22 9:18 ` Matthias Maennich
2019-08-22 11:00 ` Markus Elfring
2019-08-13 12:17 ` [PATCH v2 09/10] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-13 12:42 ` Greg KH
2019-08-13 13:12 ` Greg KH
2019-08-13 12:17 ` [PATCH v2 10/10] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-13 12:45 ` Greg KH
2019-08-13 12:47 ` Greg KH
2019-08-13 15:02 ` Matthias Maennich
[not found] ` <20190821114955.12788-1-maennich@google.com>
2019-08-21 11:49 ` [PATCH v3 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 03/11] module: add support for symbol namespaces Matthias Maennich
2019-08-27 15:37 ` Jessica Yu
2019-08-27 16:04 ` Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 04/11] modpost: " Matthias Maennich
2019-08-26 16:21 ` Jessica Yu
2019-08-27 14:41 ` Matthias Maennich
2019-08-28 9:43 ` Jessica Yu
2019-08-28 9:55 ` Matthias Maennich
2019-08-28 10:16 ` Jessica Yu
2019-08-21 11:49 ` [PATCH v3 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-28 10:49 ` Jessica Yu
2019-08-28 10:56 ` Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-21 11:49 ` [PATCH v3 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-08-22 6:09 ` [v3 " Markus Elfring
2019-08-29 12:13 ` [PATCH v3 " Jessica Yu
2019-08-21 11:49 ` [PATCH v3 09/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-21 12:37 ` Greg KH
2019-08-21 13:21 ` Thomas Gleixner
2019-08-21 13:32 ` Greg KH
2019-08-21 11:49 ` [PATCH v3 10/11] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-21 12:38 ` Greg KH
2019-08-21 14:36 ` Jessica Yu
2019-08-21 23:13 ` Christoph Hellwig
2019-08-22 8:32 ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 00/12] Symbol Namespaces Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 01/12] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 02/12] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 03/12] module: add support for symbol namespaces Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 04/12] modpost: " Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 05/12] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 06/12] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 07/12] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 08/12] scripts: Coccinelle script for " Matthias Maennich
2019-09-04 9:53 ` Masahiro Yamada
2019-09-05 14:46 ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 09/12] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-04 7:16 ` Greg KH
2019-09-03 15:06 ` [PATCH v4 10/12] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 11/12] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace Matthias Maennich
2019-09-03 16:10 ` Guenter Roeck
2019-09-04 8:45 ` Masahiro Yamada
2019-09-04 12:12 ` Guenter Roeck
2019-09-04 16:16 ` [usb-storage] " Matthew Dharm
2019-09-05 10:41 ` Jessica Yu
2019-09-05 10:52 ` Arnd Bergmann
2019-09-05 11:16 ` Jessica Yu
2019-09-05 11:25 ` Masahiro Yamada
2019-09-05 12:00 ` Greg Kroah-Hartman
2019-09-05 11:25 ` Matthias Maennich
2019-09-04 9:37 ` [PATCH v4 00/12] Symbol Namespaces Masahiro Yamada
2019-09-06 10:32 ` [PATCH v5 00/11] " Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 03/11] module: add support for symbol namespaces Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 04/11] modpost: " Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 09/11] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-06 10:32 ` [PATCH v5 10/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-06 12:59 ` Jessica Yu
2019-09-06 13:22 ` Greg KH
2019-09-06 10:32 ` [PATCH v5 11/11] usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-09 8:35 ` [PATCH v5 00/11] Symbol Namespaces Jessica Yu
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=20190813121733.52480-3-maennich@google.com \
--to=maennich@google.com \
--cc=akpm@linux-foundation.org \
--cc=ard.biesheuvel@linaro.org \
--cc=arnd@arndb.de \
--cc=geert@linux-m68k.org \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=jeyu@kernel.org \
--cc=joel@joelfernandes.org \
--cc=kernel-team@android.com \
--cc=kstewart@linuxfoundation.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-m68k@lists.linux-m68k.org \
--cc=linux-modules@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=lucas.de.marchi@gmail.com \
--cc=maco@android.com \
--cc=maco@google.com \
--cc=michal.lkml@markovi.net \
--cc=mingo@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=nico@fluxnic.net \
--cc=oneukum@suse.com \
--cc=pombredanne@nexb.com \
--cc=sam@ravnborg.org \
--cc=sboyd@codeaurora.org \
--cc=sspatil@google.com \
--cc=stern@rowland.harvard.edu \
--cc=tglx@linutronix.de \
--cc=usb-storage@lists.one-eyed-alien.net \
--cc=x86@kernel.org \
--cc=yamada.masahiro@socionext.com \
/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).