From 10fad5e46f6c7bdfb01b1a012380a38e3c6ab346 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 10 Mar 2010 18:57:54 +0900 Subject: [PATCH] percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo Acked-by: Peter Zijlstra Cc: Rusty Russell Cc: Ingo Molnar --- include/linux/module.h | 1 + include/linux/percpu.h | 7 +++++++ kernel/lockdep.c | 21 +++++---------------- kernel/module.c | 38 ++++++++++++++++++++++++++++++++++++++ mm/percpu.c | 26 ++++++++++++++++++++++++++ 5 files changed, 77 insertions(+), 16 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 87d247a..f0e2659 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -395,6 +395,7 @@ static inline int module_is_live(struct module *mod) struct module *__module_text_address(unsigned long addr); struct module *__module_address(unsigned long addr); bool is_module_address(unsigned long addr); +bool is_module_percpu_address(unsigned long addr); bool is_module_text_address(unsigned long addr); static inline int within_module_core(unsigned long addr, struct module *mod) diff --git a/include/linux/percpu.h b/include/linux/percpu.h index a93e5bf..11d5f83 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -137,6 +137,7 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size, extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align); extern void __percpu *__alloc_percpu(size_t size, size_t align); extern void free_percpu(void __percpu *__pdata); +extern bool is_kernel_percpu_address(unsigned long addr); extern phys_addr_t per_cpu_ptr_to_phys(void *addr); #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA @@ -163,6 +164,12 @@ static inline void free_percpu(void __percpu *p) kfree(p); } +/* can't distinguish from other static vars, always false */ +static inline bool is_kernel_percpu_address(unsigned long addr) +{ + return false; +} + static inline phys_addr_t per_cpu_ptr_to_phys(void *addr) { return __pa(addr); diff --git a/kernel/lockdep.c b/kernel/lockdep.c index c927a549..9bbb9c8 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -582,9 +582,6 @@ static int static_obj(void *obj) unsigned long start = (unsigned long) &_stext, end = (unsigned long) &_end, addr = (unsigned long) obj; -#ifdef CONFIG_SMP - int i; -#endif /* * static variable? @@ -595,24 +592,16 @@ static int static_obj(void *obj) if (arch_is_kernel_data(addr)) return 1; -#ifdef CONFIG_SMP /* - * percpu var? + * in-kernel percpu var? */ - for_each_possible_cpu(i) { - start = (unsigned long) &__per_cpu_start + per_cpu_offset(i); - end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM - + per_cpu_offset(i); - - if ((addr >= start) && (addr < end)) - return 1; - } -#endif + if (is_kernel_percpu_address(addr)) + return 1; /* - * module var? + * module static or percpu var? */ - return is_module_address(addr); + return is_module_address(addr) || is_module_percpu_address(addr); } /* diff --git a/kernel/module.c b/kernel/module.c index e7a6e53..9f8d23d 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -415,6 +415,40 @@ static void percpu_modcopy(struct module *mod, memcpy(per_cpu_ptr(mod->percpu, cpu), from, size); } +/** + * is_module_percpu_address - test whether address is from module static percpu + * @addr: address to test + * + * Test whether @addr belongs to module static percpu area. + * + * RETURNS: + * %true if @addr is from module static percpu area + */ +bool is_module_percpu_address(unsigned long addr) +{ + struct module *mod; + unsigned int cpu; + + preempt_disable(); + + list_for_each_entry_rcu(mod, &modules, list) { + if (!mod->percpu_size) + continue; + for_each_possible_cpu(cpu) { + void *start = per_cpu_ptr(mod->percpu, cpu); + + if ((void *)addr >= start && + (void *)addr < start + mod->percpu_size) { + preempt_enable(); + return true; + } + } + } + + preempt_enable(); + return false; +} + #else /* ... !CONFIG_SMP */ static inline void __percpu *mod_percpu(struct module *mod) @@ -441,6 +475,10 @@ static inline void percpu_modcopy(struct module *mod, /* pcpusec should be 0, and size of that section should be 0. */ BUG_ON(size != 0); } +bool is_module_percpu_address(unsigned long addr) +{ + return false; +} #endif /* CONFIG_SMP */ diff --git a/mm/percpu.c b/mm/percpu.c index 768419d..6e09741 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1304,6 +1304,32 @@ void free_percpu(void __percpu *ptr) EXPORT_SYMBOL_GPL(free_percpu); /** + * is_kernel_percpu_address - test whether address is from static percpu area + * @addr: address to test + * + * Test whether @addr belongs to in-kernel static percpu area. Module + * static percpu areas are not considered. For those, use + * is_module_percpu_address(). + * + * RETURNS: + * %true if @addr is from in-kernel static percpu area, %false otherwise. + */ +bool is_kernel_percpu_address(unsigned long addr) +{ + const size_t static_size = __per_cpu_end - __per_cpu_start; + void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr); + unsigned int cpu; + + for_each_possible_cpu(cpu) { + void *start = per_cpu_ptr(base, cpu); + + if ((void *)addr >= start && (void *)addr < start + static_size) + return true; + } + return false; +} + +/** * per_cpu_ptr_to_phys - convert translated percpu address to physical address * @addr: the address to be converted to physical address * -- 1.8.2.3