On Sun, Nov 08, 2015 at 10:24:49PM +0000, Julia Lawall wrote: > On Mon, 9 Nov 2015, Dan Carpenter wrote: > > > Cool. So, in grsec they use a GCC plugin to make these const > > automatically since they only contain function pointers. There about > > 100 struct types marked as __no_const. Kees would like to adopt the > > grsec pluggin approach I expect. Do you have an idea how many structs > > only contain function pointers or how many consts we would have to add > > to get the same effect without the plugin? > > My list has 373 type names. In the list there are counts for good > (already const) and bad (not const). The sum of the bad values is 2467. > The list is below. > > julia Fantastic! Thanks. We could autogenerate the list of type names and make checkpatch.pl complain if we declared those types as non const. I ran this command to find which functions grsec marks as __no_const. egrep '(^ struct |^@@|__no_const;)' grsecurity-3.1-4.2.5-201511021814.patch | grep __no_const -B1 | grep -v __no_const | grep -v '^--' | cut -d @ -f 5- | cut -b 9- | cut -d ' ' -f 1 There are 60 structs declared as __no_const. For some structs they declare a no_const version and use it as needed. Like this: typedef struct net_device_ops __no_const net_device_ops_no_const; grep __no_const grsecurity-3.1-4.2.5-201511021814.patch | grep typedef | cut -d ' ' -f 3 There are 32 of those. Then I compared to see if their structs were on your list. For some reason there quite a few one their list which are not on yours. Out of the first 10 about half weren't on your list. cpu_cache_fns, outer_cache_fns, psci_operations, smp_operations, omap_hwmod_soc_ops, smp_ops_t. These are mostly different arches? Also bit_table has in int has well as a function pointers but it is on their list. I'm not sure why. Maybe they are marking structs const that I don't know about. The other trick that they do is they define structs as __do_const if they want them to be const by default, which is pretty neat. This feels like it should be a standard GCC feature. In the meantime we could mark things as __do_const and print a sparse warning if it was declared as not const. I have attached the list of __no_const structs. regards, dan carpenter
cpu_cache_fns cpuidle_ops outer_cache_fns cpu_user_fns psci_operations smp_operations cpu_pm_ops omap_hwmod_soc_ops smp_ops_t machine_ops smp_ops x86_init_ops x86_cpuinit_ops x86_platform_ops x86_msi_ops x86_io_apic_ops cryptd_blkcipher_request_ctx cryptd_aead_request_ctx od_ops amd_decoder_ops kernel_queue_ops bit_table af9033_ops dib_fe_xfer_ops dib7000p_ops dib8000_ops xpc_interface l2t_skb_cb ath10k_htc_ops ath10k_htc_ep_ops ath_hw_private_ops ath_hw_ops bfa_itn_s bfa_ioc_cbfn_s bfa_ioc_hwif_s fbtft_ops ldlm_callback_suite md_ops hal_ops _io_ops visorchipset_busdev_notifiers visorchipset_busdev_responders via_clock drm_encoder_helper_funcs ttm_mem_shrink cleancache_ops cipher_tfm compress_tfm softirq_action gpd_dev_ops rchan_callbacks rio_ops renesas_usbhs_driver_callback cfctrl_rsp iw_cm_verbs snd_compr_ops lane2_ops rtnl_link tipc_nl_compat_cmd_dump tipc_nl_compat_cmd_doit Sometimes not const: fw_card_driver dm_space_map v4l2_ioctl_info xpc_arch_operations drm_info_list clk_ops global_attr cpuidle_state device_attribute efivar_operations fb_ops file_operations sensor_device_attribute sensor_device_attribute_2 i2c_algorithm irq_chip irq_chip kobj_attribute vm_operations_struct module_attribute net_device_ops notifier_block hotplug_slot_ops dev_pm_domain user_regset seq_operations ctl_table attribute attribute_group bin_attribute libfc_function_template fc_function_template
