diff options
Diffstat (limited to 'kernel/livepatch')
| -rw-r--r-- | kernel/livepatch/Kconfig | 12 | ||||
| -rw-r--r-- | kernel/livepatch/core.c | 53 | ||||
| -rw-r--r-- | kernel/livepatch/transition.c | 49 |
3 files changed, 68 insertions, 46 deletions
diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig index 53d51ed619a3..4c0a9c18d0b2 100644 --- a/kernel/livepatch/Kconfig +++ b/kernel/livepatch/Kconfig @@ -18,3 +18,15 @@ config LIVEPATCH module uses the interface provided by this option to register a patch, causing calls to patched functions to be redirected to new function code contained in the patch module. + +config HAVE_KLP_BUILD + bool + help + Arch supports klp-build + +config KLP_BUILD + def_bool y + depends on LIVEPATCH && HAVE_KLP_BUILD + select OBJTOOL + help + Enable klp-build support diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 3c21c31796db..9917756dae46 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -59,7 +59,7 @@ static void klp_find_object_module(struct klp_object *obj) if (!klp_is_module(obj)) return; - rcu_read_lock_sched(); + guard(rcu)(); /* * We do not want to block removal of patched modules and therefore * we do not take a reference here. The patches are removed by @@ -75,8 +75,6 @@ static void klp_find_object_module(struct klp_object *obj) */ if (mod && mod->klp_alive) obj->mod = mod; - - rcu_read_unlock_sched(); } static bool klp_initialized(void) @@ -90,8 +88,14 @@ static struct klp_func *klp_find_func(struct klp_object *obj, struct klp_func *func; klp_for_each_func(obj, func) { + /* + * Besides identical old_sympos, also consider old_sympos + * of 0 and 1 are identical. + */ if ((strcmp(old_func->old_name, func->old_name) == 0) && - (old_func->old_sympos == func->old_sympos)) { + ((old_func->old_sympos == func->old_sympos) || + (old_func->old_sympos == 0 && func->old_sympos == 1) || + (old_func->old_sympos == 1 && func->old_sympos == 0))) { return func; } } @@ -219,14 +223,14 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); if (sym->st_shndx != SHN_LIVEPATCH) { - pr_err("symbol %s is not marked as a livepatch symbol\n", - strtab + sym->st_name); + pr_err("symbol %s at rela sec %u idx %d is not marked as a livepatch symbol\n", + strtab + sym->st_name, symndx, i); return -EINVAL; } /* Format: .klp.sym.sym_objname.sym_name,sympos */ cnt = sscanf(strtab + sym->st_name, - ".klp.sym.%55[^.].%511[^,],%lu", + KLP_SYM_PREFIX "%55[^.].%511[^,],%lu", sym_objname, sym_name, &sympos); if (cnt != 3) { pr_err("symbol %s has an incorrectly formatted name\n", @@ -305,7 +309,7 @@ static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, * See comment in klp_resolve_symbols() for an explanation * of the selected field width value. */ - cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", + cnt = sscanf(shstrtab + sec->sh_name, KLP_RELOC_SEC_PREFIX "%55[^.]", sec_objname); if (cnt != 1) { pr_err("section %s has an incorrectly formatted name\n", @@ -347,6 +351,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, * /sys/kernel/livepatch/<patch>/transition * /sys/kernel/livepatch/<patch>/force * /sys/kernel/livepatch/<patch>/replace + * /sys/kernel/livepatch/<patch>/stack_order * /sys/kernel/livepatch/<patch>/<object> * /sys/kernel/livepatch/<patch>/<object>/patched * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> @@ -452,15 +457,38 @@ static ssize_t replace_show(struct kobject *kobj, return sysfs_emit(buf, "%d\n", patch->replace); } +static ssize_t stack_order_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct klp_patch *patch, *this_patch; + int stack_order = 0; + + this_patch = container_of(kobj, struct klp_patch, kobj); + + mutex_lock(&klp_mutex); + + klp_for_each_patch(patch) { + stack_order++; + if (patch == this_patch) + break; + } + + mutex_unlock(&klp_mutex); + + return sysfs_emit(buf, "%d\n", stack_order); +} + static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); static struct kobj_attribute replace_kobj_attr = __ATTR_RO(replace); +static struct kobj_attribute stack_order_kobj_attr = __ATTR_RO(stack_order); static struct attribute *klp_patch_attrs[] = { &enabled_kobj_attr.attr, &transition_kobj_attr.attr, &force_kobj_attr.attr, &replace_kobj_attr.attr, + &stack_order_kobj_attr.attr, NULL }; ATTRIBUTE_GROUPS(klp_patch); @@ -577,9 +605,12 @@ static int klp_add_object_nops(struct klp_patch *patch, } /* - * Add 'nop' functions which simply return to the caller to run - * the original function. The 'nop' functions are added to a - * patch to facilitate a 'replace' mode. + * Add 'nop' functions which simply return to the caller to run the + * original function. + * + * They are added only when the atomic replace mode is used and only for + * functions which are currently livepatched but are no longer included + * in the new livepatch. */ static int klp_add_nops(struct klp_patch *patch) { diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index ba069459c101..2351a19ac2a9 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -29,22 +29,13 @@ static unsigned int klp_signals_cnt; /* * When a livepatch is in progress, enable klp stack checking in - * cond_resched(). This helps CPU-bound kthreads get patched. + * schedule(). This helps CPU-bound kthreads get patched. */ -#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) - -#define klp_cond_resched_enable() sched_dynamic_klp_enable() -#define klp_cond_resched_disable() sched_dynamic_klp_disable() - -#else /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */ DEFINE_STATIC_KEY_FALSE(klp_sched_try_switch_key); -EXPORT_SYMBOL(klp_sched_try_switch_key); -#define klp_cond_resched_enable() static_branch_enable(&klp_sched_try_switch_key) -#define klp_cond_resched_disable() static_branch_disable(&klp_sched_try_switch_key) - -#endif /* CONFIG_PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */ +#define klp_resched_enable() static_branch_enable(&klp_sched_try_switch_key) +#define klp_resched_disable() static_branch_disable(&klp_sched_try_switch_key) /* * This work can be performed periodically to finish patching or unpatching any @@ -365,26 +356,18 @@ static bool klp_try_switch_task(struct task_struct *task) void __klp_sched_try_switch(void) { - if (likely(!klp_patch_pending(current))) - return; - /* - * This function is called from cond_resched() which is called in many - * places throughout the kernel. Using the klp_mutex here might - * deadlock. - * - * Instead, disable preemption to prevent racing with other callers of - * klp_try_switch_task(). Thanks to task_call_func() they won't be - * able to switch this task while it's running. + * This function is called from __schedule() while a context switch is + * about to happen. Preemption is already disabled and klp_mutex + * can't be acquired. + * Disabled preemption is used to prevent racing with other callers of + * klp_try_switch_task(). Thanks to task_call_func() they won't be + * able to switch to this task while it's running. */ - preempt_disable(); + lockdep_assert_preemption_disabled(); - /* - * Make sure current didn't get patched between the above check and - * preempt_disable(). - */ - if (unlikely(!klp_patch_pending(current))) - goto out; + if (likely(!klp_patch_pending(current))) + return; /* * Enforce the order of the TIF_PATCH_PENDING read above and the @@ -395,11 +378,7 @@ void __klp_sched_try_switch(void) smp_rmb(); klp_try_switch_task(current); - -out: - preempt_enable(); } -EXPORT_SYMBOL(__klp_sched_try_switch); /* * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set. @@ -508,7 +487,7 @@ void klp_try_complete_transition(void) } /* Done! Now cleanup the data structures. */ - klp_cond_resched_disable(); + klp_resched_disable(); patch = klp_transition_patch; klp_complete_transition(); @@ -560,7 +539,7 @@ void klp_start_transition(void) set_tsk_thread_flag(task, TIF_PATCH_PENDING); } - klp_cond_resched_enable(); + klp_resched_enable(); klp_signals_cnt = 0; } |