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Message-ID: <CAPhsuW4nPo_OFwspn18N-pKpPjc6vOYBJp8hE7O5mYEweKUySg@mail.gmail.com> Date: Fri, 27 Jan 2023 13:31:51 -0800 From: Song Liu <song@...nel.org> To: Guenter Roeck <linux@...ck-us.net> Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, kernel-team@...a.com, Luis Chamberlain <mcgrof@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org> Subject: Re: [PATCH v3] module: replace module_layout with module_memory Hi Guenter, Thanks for running the test! On Fri, Jan 27, 2023 at 12:40 PM Guenter Roeck <linux@...ck-us.net> wrote: > > 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@...nel.org> > > Cc: Luis Chamberlain <mcgrof@...nel.org> > > Cc: Thomas Gleixner <tglx@...utronix.de> > > Cc: Peter Zijlstra <peterz@...radead.org> > > Cc: Guenter Roeck <linux@...ck-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; Fixed this in my local branch: diff --git c/kernel/module/main.c w/kernel/module/main.c index 32f63c6eaa61..da2bca75e4a8 100644 --- c/kernel/module/main.c +++ w/kernel/module/main.c @@ -935,8 +935,6 @@ struct module_attribute module_uevent = static ssize_t show_coresize(struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { - unsigned int size = 0; - return sprintf(buffer, "%u\n", mk->mod->mod_mem[MOD_MEM_TYPE_TEXT].size); } Song
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