• Song Liu's avatar
    module: replace module_layout with module_memory · ac3b4328
    Song Liu authored
    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_TEXT,
            MOD_DATA,
            MOD_RODATA,
            MOD_RO_AFTER_INIT,
            MOD_INIT_TEXT,
            MOD_INIT_DATA,
            MOD_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: default avatarSong 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>
    Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
    Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
    Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
    ac3b4328
strict_rwx.c 2.05 KB