On Mon, Jan 9, 2023 at 10:03 AM Christophe Leroy <christophe.leroy@xxxxxxxxxx> wrote: > > > > Le 06/01/2023 à 23:09, Song Liu a écrit : > > 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. > > > > 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. > > I dislike how it looks with enums, things like > mod->mod_mem[MOD_MEM_TYPE_INIT_TEXT] are odd and don't read nicely. > Could we have something nicer like mod->mod_mem_init_text ? > I know it will complicate your for_each_mod_mem_type() but it would look > nicer. Hmm.. I am not sure whether we want 7 module_memory here. But if we agree that it looks better like that, I am ok with it. > > Also, can you explain how you switch from two trees to only one ? > As far as I remember, the same question arised when I implemented > CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC, and the conclusion was that > we had to keep two independant trees, so I'm a bit puzzled that you have > now merged everything into a single tree. AFAICT, we only need __module_address() to work? So one tree is enough. Did I miss something? Thanks, Song
