From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
iommu@lists.linux-foundation.org,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH] iommu/io-pgtable: Move some initialization data to .init.rodata
Date: Mon, 9 Sep 2019 22:19:19 +0200 [thread overview]
Message-ID: <20190909201919.5841-1-christophe.jaillet@wanadoo.fr> (raw)
The memory used by '__init' functions can be freed once the initialization
phase has been performed.
Mark some 'static const' array defined and used within some '__init'
functions as '__initconst', so that the corresponding data can also be
discarded.
Without '__initconst', the data are put in the .rodata section.
With the qualifier, they are put in the .init.rodata section.
With gcc 8.3.0, the following changes have been measured:
Without '__initconst':
section size
.rodata 00000720
.init.rodata 00000018
With '__initconst':
section size
.rodata 00000660
.init.rodata 00000058
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Adding __initconst "within" a function is not in line with kernel/include/init.h
which states that:
* Don't forget to initialize data not at file scope, i.e. within a function,
* as gcc otherwise puts the data into the bss section and not into the init
* section.
However, having the array within the function or out-side the function
seems to have no impact in the generated code and in the section used.
According to my test, both put the data in .init.rodata.
Maybe the comment is outdated or related to some older vesion of gcc.
---
drivers/iommu/io-pgtable-arm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 161a7d56264d..24076f0560c6 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -1109,7 +1109,7 @@ static void __init arm_lpae_dump_ops(struct io_pgtable_ops *ops)
static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
{
- static const enum io_pgtable_fmt fmts[] = {
+ static const enum io_pgtable_fmt fmts[] __initconst = {
ARM_64_LPAE_S1,
ARM_64_LPAE_S2,
};
@@ -1208,13 +1208,13 @@ static int __init arm_lpae_run_tests(struct io_pgtable_cfg *cfg)
static int __init arm_lpae_do_selftests(void)
{
- static const unsigned long pgsize[] = {
+ static const unsigned long pgsize[] __initconst = {
SZ_4K | SZ_2M | SZ_1G,
SZ_16K | SZ_32M,
SZ_64K | SZ_512M,
};
- static const unsigned int ias[] = {
+ static const unsigned int ias[] __initconst = {
32, 36, 40, 42, 44, 48,
};
--
2.20.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
reply other threads:[~2019-09-09 20:19 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20190909201919.5841-1-christophe.jaillet@wanadoo.fr \
--to=christophe.jaillet@wanadoo.fr \
--cc=iommu@lists.linux-foundation.org \
--cc=joro@8bytes.org \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robin.murphy@arm.com \
--cc=will@kernel.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).