From: Xi Ruoyao <xry111@xry111.site>
To: Lulu Cheng <chenglulu@loongson.cn>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: Jinyang He <hejinyang@loongson.cn>,
Chenghua Xu <xuchenghua@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
Youling Tang <tangyouling@loongson.cn>,
Wang Xuerui <i@xen0n.name>
Subject: Re: 回复:[PATCH v5] LoongArch: add movable attribute
Date: Fri, 05 Aug 2022 11:34:38 +0800 [thread overview]
Message-ID: <3aebe438b53e84eab24824f6cc79ae655cfb0f72.camel@xry111.site> (raw)
In-Reply-To: <ea83959f38c732c4ab95c6df5df018a3834244ad.camel@xry111.site>
On Fri, 2022-08-05 at 10:51 +0800, Xi Ruoyao via Gcc-patches wrote:
> > If it is accessed through the GOT table, dynamic relocation is required when the module is loaded.
>
> Dynamic relocation is required when the module is loaded anyway. The
> .ko modules are actually relocatable ELF objects (produced by ld -r) and
> the module loader has to perform some work of a normal linker.
>
> > And accessing the got table may have a cache miss.
>
> /* snip */
>
> > So my idea is "model(normal)","model (large)" etc.
>
> Then should we have an option to disable GOT globally? Maybe for kernel
> we'll just "-mno-got -mcmodel=large" (or "extreme"? The kernel image is
> loaded at 0x9000000000000000 and the modules are above
> 0xffff000000000000 so we need to handle 64-bit offset).
Or maybe we should just use a PC-relative addressing with 4 instructions
instead of GOT for -fno-PIC? Both way consumes 16 bytes (4 instructions
for PC-relative, 2 instructions and a 64-bit GOT entry for GOT) and PC-
relative may be more cache friendly. But such a major change cannot be
backported for 12.2 IMO.
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2022-08-05 3:34 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-29 14:22 [PATCH] LoongArch: add addr_global attribute Xi Ruoyao
2022-07-29 15:31 ` [PATCH v2] " Xi Ruoyao
2022-07-29 17:17 ` [PATCH v3] " Xi Ruoyao
2022-07-30 3:13 ` Lulu Cheng
2022-07-30 6:03 ` Huacai Chen
2022-07-31 9:05 ` Chenghua Xu
2022-08-01 10:04 ` [PATCH v4] LoongArch: add movable attribute Xi Ruoyao
2022-08-01 10:07 ` [PATCH v5] " Xi Ruoyao
2022-08-03 1:36 ` Xi Ruoyao
2022-08-03 2:59 ` WANG Xuerui
2022-08-03 3:15 ` Xi Ruoyao
[not found] ` <-2muj1c-68saz6jhkcyw3jo1xp-1mgcvnkbqi2wjp6tue-qsso54-emxgu3-k85590-kpgox7-w67u6h3cai1l-5bi887dsgzsu-g4d7i7-wl316qxrucx4kv4on7-mnna36-iremg8-nwc5ot-9041t2-hu8nsl.1659495047941@email.android.com>
2022-08-03 3:10 ` 回复:[PATCH " Xi Ruoyao
2022-08-04 7:47 ` Xi Ruoyao
2022-08-05 1:05 ` Lulu Cheng
2022-08-05 1:28 ` Xi Ruoyao
2022-08-05 2:38 ` Lulu Cheng
2022-08-05 2:51 ` Xi Ruoyao
2022-08-05 3:34 ` Xi Ruoyao [this message]
2022-08-05 3:45 ` Xi Ruoyao
2022-08-05 4:01 ` Lulu Cheng
2022-08-05 6:03 ` Xi Ruoyao
2022-08-05 7:19 ` Lulu Cheng
2022-08-05 7:41 ` WANG Xuerui
2022-08-05 7:58 ` Lulu Cheng
2022-08-05 9:53 ` Xi Ruoyao
2022-08-08 4:53 ` Lulu Cheng
2022-08-09 11:30 ` Xi Ruoyao
2022-08-09 13:03 ` Lulu Cheng
2022-08-09 14:04 ` Xi Ruoyao
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