lwn.git/kernel/module.c, branch v4.5.7

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

2016-02-19T00:34:15+00:00

Pull livepatching fixes from Jiri Kosina: - regression (from 4.4) fix for ordering issue, introduced by an earlier ftrace change, that broke live patching of modules. The fix replaces the ftrace module notifier by direct call in order to make the ordering guaranteed and well-defined. The patch, from Jessica Yu, has been acked both by Steven and Rusty - error message fix from Miroslav Benes * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching: ftrace/module: remove ftrace module notifier livepatch: change the error message in asm/livepatch.h header files

ftrace/module: remove ftrace module notifier

2016-02-17T21:14:06+00:00

Remove the ftrace module notifier in favor of directly calling ftrace_module_enable() and ftrace_release_mod() in the module loader. Hard-coding the function calls directly in the module loader removes dependence on the module notifier call chain and provides better visibility and control over what gets called when, which is important to kernel utilities such as livepatch. This fixes a notifier ordering issue in which the ftrace module notifier (and hence ftrace_module_enable()) for coming modules was being called after klp_module_notify(), which caused livepatch modules to initialize incorrectly. This patch removes dependence on the module notifier call chain in favor of hard coding the corresponding function calls in the module loader. This ensures that ftrace and livepatch code get called in the correct order on patch module load and unload. Fixes: 5156dca34a3e ("ftrace: Fix the race between ftrace and insmod") Signed-off-by: Jessica Yu Reviewed-by: Steven Rostedt Reviewed-by: Petr Mladek Acked-by: Rusty Russell Reviewed-by: Josh Poimboeuf Reviewed-by: Miroslav Benes Signed-off-by: Jiri Kosina

modules: fix longstanding /proc/kallsyms vs module insertion race.

2016-02-03T06:28:15+00:00

For CONFIG_KALLSYMS, we keep two symbol tables and two string tables. There's one full copy, marked SHF_ALLOC and laid out at the end of the module's init section. There's also a cut-down version that only contains core symbols and strings, and lives in the module's core section. After module init (and before we free the module memory), we switch the mod->symtab, mod->num_symtab and mod->strtab to point to the core versions. We do this under the module_mutex. However, kallsyms doesn't take the module_mutex: it uses preempt_disable() and rcu tricks to walk through the modules, because it's used in the oops path. It's also used in /proc/kallsyms. There's nothing atomic about the change of these variables, so we can get the old (larger!) num_symtab and the new symtab pointer; in fact this is what I saw when trying to reproduce. By grouping these variables together, we can use a carefully-dereferenced pointer to ensure we always get one or the other (the free of the module init section is already done in an RCU callback, so that's safe). We allocate the init one at the end of the module init section, and keep the core one inside the struct module itself (it could also have been allocated at the end of the module core, but that's probably overkill). Reported-by: Weilong Chen Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111541 Cc: stable@kernel.org Signed-off-by: Rusty Russell

module: wrapper for symbol name.

2016-02-03T06:28:14+00:00

This trivial wrapper adds clarity and makes the following patch smaller. Cc: stable@kernel.org Signed-off-by: Rusty Russell

modules: fix modparam async_probe request

2016-02-03T06:28:14+00:00

Commit f2411da746985 ("driver-core: add driver module asynchronous probe support") added async probe support, in two forms: * in-kernel driver specification annotation * generic async_probe module parameter (modprobe foo async_probe) To support the generic kernel parameter parse_args() was extended via commit ecc8617053e0 ("module: add extra argument for parse_params() callback") however commit failed to f2411da746985 failed to add the required argument. This causes a crash then whenever async_probe generic module parameter is used. This was overlooked when the form in which in-kernel async probe support was reworked a bit... Fix this as originally intended. Cc: Hannes Reinecke Cc: Dmitry Torokhov Cc: stable@vger.kernel.org (4.2+) Signed-off-by: Luis R. Rodriguez Signed-off-by: Rusty Russell [minimized]

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

2016-01-15T00:38:02+00:00

Pull livepatching updates from Jiri Kosina: - RO/NX attribute fixes for patch module relocations from Josh Poimboeuf. As part of this effort, module.c has been cleaned up as well and livepatching is piggy-backing on this cleanup. Rusty is OK with this whole lot going through livepatching tree. - symbol disambiguation support from Chris J Arges. That series is also Reviewed-by: Miroslav Benes but this came in only after I've alredy pushed out. Didn't want to rebase because of that, hence I am mentioning it here. - symbol lookup fix from Miroslav Benes * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching: livepatch: Cleanup module page permission changes module: keep percpu symbols in module's symtab module: clean up RO/NX handling. module: use a structure to encapsulate layout. gcov: use within_module() helper. module: Use the same logic for setting and unsetting RO/NX livepatch: function,sympos scheme in livepatch sysfs directory livepatch: add sympos as disambiguator field to klp_reloc livepatch: add old_sympos as disambiguator field to klp_func

ftrace/module: Call clean up function when module init fails early

2016-01-07T17:17:39+00:00

If the module init code fails after calling ftrace_module_init() and before calling do_init_module(), we can suffer from a memory leak. This is because ftrace_module_init() allocates pages to store the locations that ftrace hooks are placed in the module text. If do_init_module() fails, it still calls the MODULE_GOING notifiers which will tell ftrace to do a clean up of the pages it allocated for the module. But if load_module() fails before then, the pages allocated by ftrace_module_init() will never be freed. Call ftrace_release_mod() on the module if load_module() fails before getting to do_init_module(). Link: http://lkml.kernel.org/r/567CEA31.1070507@intel.com Reported-by: "Qiu, PeiyangX" Fixes: a949ae560a511 "ftrace/module: Hardcode ftrace_module_init() call into load_module()" Cc: stable@vger.kernel.org # v2.6.38+ Acked-by: Rusty Russell Signed-off-by: Steven Rostedt

module: keep percpu symbols in module's symtab

2015-12-04T21:46:26+00:00

Currently, percpu symbols from .data..percpu ELF section of a module are not copied over and stored in final symtab array of struct module. Consequently such symbol cannot be returned via kallsyms API (for example kallsyms_lookup_name). This can be especially confusing when the percpu symbol is exported. Only its __ksymtab et al. are present in its symtab. The culprit is in layout_and_allocate() function where SHF_ALLOC flag is dropped for .data..percpu section. There is in fact no need to copy the section to final struct module, because kernel module loader allocates extra percpu section by itself. Unfortunately only symbols from SHF_ALLOC sections are copied due to a check in is_core_symbol(). The patch changes is_core_symbol() function to copy over also percpu symbols (their st_shndx points to .data..percpu ELF section). We do it only if CONFIG_KALLSYMS_ALL is set to be consistent with the rest of the function (ELF section is SHF_ALLOC but !SHF_EXECINSTR). Finally elf_type() returns type 'a' for a percpu symbol because its address is absolute. Signed-off-by: Miroslav Benes Signed-off-by: Rusty Russell Signed-off-by: Jiri Kosina

module: clean up RO/NX handling.

2015-12-04T21:46:26+00:00

Modules have three sections: text, rodata and writable data. The code handled the case where these overlapped, however they never can: debug_align() ensures they are always page-aligned. This is why we got away with manually traversing the pages in set_all_modules_text_rw() without rounding. We create three helper functions: frob_text(), frob_rodata() and frob_writable_data(). We then call these explicitly at every point, so it's clear what we're doing. We also expose module_enable_ro() and module_disable_ro() for livepatch to use. Reviewed-by: Josh Poimboeuf Signed-off-by: Rusty Russell Signed-off-by: Jiri Kosina

module: use a structure to encapsulate layout.

2015-12-04T21:46:25+00:00

Makes it easier to handle init vs core cleanly, though the change is fairly invasive across random architectures. It simplifies the rbtree code immediately, however, while keeping the core data together in the same cachline (now iff the rbtree code is enabled). Acked-by: Peter Zijlstra Reviewed-by: Josh Poimboeuf Signed-off-by: Rusty Russell Signed-off-by: Jiri Kosina