Messages in this thread Patch in this message | | | Date | Wed, 10 Mar 2010 18:57:54 +0900 | From | Tejun Heo <> | Subject | [PATCH 2/2] percpu,module: implement and use is_kernel/module_percpu_address() |
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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 <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> --- I went for is_kernel/module_percpu_address() so that the tests are orthogonal. Tested on SMP and UP. If no one objects, I'll put this into percpu#for-linus for a while and push it to Linus.
Thanks.
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(-)
Index: work/include/linux/module.h =================================================================== --- work.orig/include/linux/module.h +++ work/include/linux/module.h @@ -394,6 +394,7 @@ static inline int module_is_live(struct 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) Index: work/include/linux/percpu.h =================================================================== --- work.orig/include/linux/percpu.h +++ work/include/linux/percpu.h @@ -137,6 +137,7 @@ extern int __init pcpu_page_first_chunk( 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 __pe 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); Index: work/kernel/lockdep.c =================================================================== --- work.orig/kernel/lockdep.c +++ work/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); } /* Index: work/kernel/module.c =================================================================== --- work.orig/kernel/module.c +++ work/kernel/module.c @@ -415,6 +415,40 @@ static void percpu_modcopy(struct module 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 /* 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 */ Index: work/mm/percpu.c =================================================================== --- work.orig/mm/percpu.c +++ work/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 *
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