From: Guenter Roeck <linux@roeck-us.net>
To: Song Liu <song@kernel.org>
Cc: linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, Luis Chamberlain <mcgrof@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3] module: replace module_layout with module_memory
Date: Fri, 27 Jan 2023 12:40:11 -0800 [thread overview]
Message-ID: <20230127204011.GA45594@roeck-us.net> (raw)
In-Reply-To: <20230126233606.1317794-1-song@kernel.org>
On Thu, Jan 26, 2023 at 03:36:06PM -0800, Song Liu wrote:
> module_layout manages different types of memory (text, data, rodata, etc.)
> in one allocation, which is problematic for some reasons:
>
> 1. It is hard to enable CONFIG_STRICT_MODULE_RWX.
> 2. It is hard to use huge pages in modules (and not break strict rwx).
> 3. Many archs uses module_layout for arch-specific data, but it is not
> obvious how these data are used (are they RO, RX, or RW?)
>
> Improve the scenario by replacing 2 (or 3) module_layout per module with
> up to 7 module_memory per module:
>
> MOD_MEM_TYPE_TEXT,
> MOD_MEM_TYPE_DATA,
> MOD_MEM_TYPE_RODATA,
> MOD_MEM_TYPE_RO_AFTER_INIT,
> MOD_MEM_TYPE_INIT_TEXT,
> MOD_MEM_TYPE_INIT_DATA,
> MOD_MEM_TYPE_INIT_RODATA,
>
> and allocating them separately. This adds slightly more entries to
> mod_tree (from up to 3 entries per module, to up to 7 entries per
> module). However, this at most adds a small constant overhead to
> __module_address(), which is expected to be fast.
>
> Various archs use module_layout for different data. These data are put
> into different module_memory based on their location in module_layout.
> IOW, data that used to go with text is allocated with MOD_MEM_TYPE_TEXT;
> data that used to go with data is allocated with MOD_MEM_TYPE_DATA, etc.
>
> module_memory simplifies quite some of the module code. For example,
> ARCH_WANTS_MODULES_DATA_IN_VMALLOC is a lot cleaner, as it just uses a
> different allocator for the data. kernel/module/strict_rwx.c is also
> much cleaner with module_memory.
>
> Signed-off-by: Song Liu <song@kernel.org>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Guenter Roeck <linux@roeck-us.net>
>
> ---
Build reference: v6.2-rc5-52-gc96fb00
Compiler version: powerpc64-linux-gcc (GCC) 11.3.0
Assembler version: GNU assembler (GNU Binutils) 2.39
Building powerpc:defconfig ... passed
Building powerpc:allmodconfig ... passed
Building powerpc:ppc32_allmodconfig ... failed
--------------
Error log:
kernel/module/main.c: In function 'show_coresize':
kernel/module/main.c:938:22: error: unused variable 'size' [-Werror=unused-variable]
938 | unsigned int size = 0;
That is the only failure reported by my test system.
Guenter
next prev parent reply other threads:[~2023-01-27 20:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-26 23:36 [PATCH v3] module: replace module_layout with module_memory Song Liu
2023-01-26 23:58 ` Luis Chamberlain
2023-01-27 20:40 ` Guenter Roeck [this message]
2023-01-27 21:31 ` Song Liu
2023-01-29 2:30 ` Luis Chamberlain
2023-01-29 15:35 ` Guenter Roeck
2023-01-30 0:18 ` Luis Chamberlain
2023-01-28 7:43 ` Christophe Leroy
2023-01-29 6:04 ` Song Liu
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