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@xxxxxxxxxx> > Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Guenter Roeck <linux@xxxxxxxxxxxx> > > --- 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
