Fix the absence of warning message and kernel tainting when initializing drivers from the `drivers/staging` subtree from initcalls (when configured as built-in). When such a driver is built as module and the module is loaded, the `load_module()` function taints the kernel to signal code of unknown quality is loaded, and produces a warning like this: [ 8.076352] rts5208: module is from the staging directory, the quality is unknown, you have been warned. The same behaviour is absent, however, when a staging driver is compiled as built-in on the kernel image, since loading it happens through initcalls and not through load_module(). This might prevent relevant information of being available on a bug report (i.e. on a panic log) among other possible problems. NOTES: - The patch is written in such a way that all non-staging drivers are kept the way they were, except for staging drivers built with `-DSTAGING_CODE`. - Since it changes some macros related to clang LTO as well, I tested it and it works properly in kernels compiled with both clang and gcc. - Some `checkpatch.pl` errors, warnings and checks (with `--strict`) are present. Some were already there, some I introduced but I think they're unavoidable. Some IMHO don´t make sense at all, I think they would apply for most regular macros but initcall macros are just way different. Signed-off-by: Ágatha Isabelle Chris Moreira Guedes <code@xxxxxxxxxx> --- CHANGELOG v2: - Changed the way we hook into the initcalls as suggested by Uwe, and moved the logic from `include/linux/module.h` to `include/linux/init.h`. - Adjusted accordingly to work with both GCC and clang with `CONFIG_LTO_CLANG=y`, since some init scripts required that. - Fixed the missing space pointed out by Dan & other minor string details. - Changed the subject, since it became somewhat more of an init thing than a staging thing. drivers/staging/Makefile | 2 ++ include/linux/init.h | 76 ++++++++++++++++++++++++++++++++++------ init/main.c | 20 +++++++++++ kernel/module/main.c | 4 +-- 4 files changed, 88 insertions(+), 14 deletions(-) diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile index 5390879b5d1b..7cea13436426 100644 --- a/drivers/staging/Makefile +++ b/drivers/staging/Makefile @@ -1,6 +1,8 @@ # SPDX-License-Identifier: GPL-2.0 # Makefile for staging directory +subdir-ccflags-y += -DSTAGING_CODE + obj-y += media/ obj-$(CONFIG_FB_OLPC_DCON) += olpc_dcon/ obj-$(CONFIG_RTL8192E) += rtl8192e/ diff --git a/include/linux/init.h b/include/linux/init.h index 58cef4c2e59a..c7afee978b42 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -188,6 +188,8 @@ extern struct module __this_module; #ifndef __ASSEMBLY__ +extern void staging_taint(const char *code_id, bool module); + /* * initcalls are now grouped by functionality into separate * subsections. Ordering inside the subsections is determined @@ -220,6 +222,14 @@ extern struct module __this_module; __PASTE(__, \ __PASTE(__iid, id)))) +#define __define_stub_fn(___stub, fn, __taintcall) \ + int __init ___stub(void); \ + int __init ___stub(void) \ + { \ + __taintcall(); \ + return fn(); \ + } \ + #ifdef CONFIG_LTO_CLANG /* * With LTO, the compiler doesn't necessarily obey link order for @@ -230,31 +240,75 @@ extern struct module __this_module; #define __initcall_section(__sec, __iid) \ #__sec ".init.." #__iid +#define ___define_initcall_stub(__stub, fn, __taintcall) \ + __define_stub_fn(__stub, fn, __taintcall) \ + __ADDRESSABLE(__stub) +#else +#define __initcall_section(__sec, __iid) \ + #__sec ".init" + +#define ___define_initcall_stub(__stub, fn, __taintcall) \ + __ADDRESSABLE(fn) +#endif /* CONFIG_LTO_CLANG */ + +#ifdef STAGING_CODE + /* * With LTO, the compiler can rename static functions to avoid * global naming collisions. We use a global stub function for * initcalls to create a stable symbol name whose address can be * taken in inline assembly when PREL32 relocations are used. + * + * Moreover, when there's staging code, regardless of LTO, we + * need to wrap the function inside a new one to taint the + * kernel and warn about it in the log. So we need this special + * symbol name for the wrapper regardless of that. */ #define __initcall_stub(fn, __iid, id) \ __initcall_name(initstub, __iid, id) +#define __staging_taint_fn() \ + staging_taint(KBUILD_MODNAME, false) + +#ifdef CONFIG_LTO_CLANG + #define __define_initcall_stub(__stub, fn) \ - int __init __stub(void); \ - int __init __stub(void) \ - { \ - return fn(); \ - } \ - __ADDRESSABLE(__stub) -#else -#define __initcall_section(__sec, __iid) \ - #__sec ".init" + ___define_initcall_stub(__stub, fn, __staging_taint_fn) + +#else /* no CONFIG_LTO_CLANG */ + +#define __define_initcall_stub(_stub, fn) \ + __define_stub_fn(_stub, fn, __staging_taint_fn) \ + __ADDRESSABLE(_stub) + +#endif /* CONFIG_LTO_CLANG */ + +#else /* no STAGING_CODE */ + +#ifdef CONFIG_LTO_CLANG + +/* + * Same case as before, it's not staging code but there's LTO + */ +#define __initcall_stub(fn, __iid, id) \ + __initcall_name(initstub, __iid, id) +#else /* no CONFIG_LTO_CLANG*/ + +/* For no LTO outside staging code, the vast majority of drivers + * can just be built with their regular symbol names as they + * just have been built all the time + */ #define __initcall_stub(fn, __iid, id) fn +#endif /* CONFIG_LTO_CLANG */ + +#define __staging_taint_fn() + #define __define_initcall_stub(__stub, fn) \ - __ADDRESSABLE(fn) -#endif + ___define_initcall_stub(__stub, fn, __staging_taint_fn) + +#endif /* STAGING_CODE */ #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS #define ____define_initcall(fn, __stub, __name, __sec) \ diff --git a/init/main.c b/init/main.c index 206acdde51f5..a297675dd397 100644 --- a/init/main.c +++ b/init/main.c @@ -1602,3 +1602,23 @@ static noinline void __init kernel_init_freeable(void) integrity_load_keys(); } + +#ifdef CONFIG_STAGING +/** + * staging_init_taint() - We need to taint the kernel whenever staging code + * is initialized (from built-in drivers) or loaded (as modules) and issue + * a warning the first time it happens. + */ +void staging_taint(const char *code_id, bool module) +{ + char *code_type = module ? "module" : "builtin driver"; + + pr_warn("%s %s: The kernel contains code from staging directory" + ", the quality is unknown, you have been warned.\n", + code_type, code_id); + + add_taint(TAINT_CRAP, LOCKDEP_STILL_OK); +} +EXPORT_SYMBOL(staging_taint); + +#endif /* CONFIG_STAGING */ diff --git a/kernel/module/main.c b/kernel/module/main.c index d18a94b973e1..d7d33336ab43 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2039,9 +2039,7 @@ static void module_augment_kernel_taints(struct module *mod, struct load_info *i check_modinfo_retpoline(mod, info); if (get_modinfo(info, "staging")) { - add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK); - pr_warn("%s: module is from the staging directory, the quality " - "is unknown, you have been warned.\n", mod->name); + staging_taint(mod->name, true); } if (is_livepatch_module(mod)) { -- 2.45.2
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