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author | Rusty Russell <rusty@rustcorp.com.au> | 2008-07-22 19:24:28 -0500 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-07-22 19:24:28 +1000 |
commit | 3a642e99babe0617febb6f402e1e063479f489db (patch) | |
tree | 09f7d6c7b0a4e3869d11c739113e5dd5a8ff5a2c | |
parent | 2f0f2a334bc38b61a9afca951185cd3844ee709d (diff) | |
download | linux-3a642e99babe0617febb6f402e1e063479f489db.tar.gz linux-3a642e99babe0617febb6f402e1e063479f489db.tar.bz2 linux-3a642e99babe0617febb6f402e1e063479f489db.zip |
modules: Take a shortcut for checking if an address is in a module
This patch keeps track of the boundaries of module allocation, in
order to speed up module_text_address().
Inspired by Arjan's version, which required arch-specific defines:
Various pieces of the kernel (lockdep, latencytop, etc) tend
to store backtraces, sometimes at a relatively high
frequency. In itself this isn't a big performance deal (after
all you're using diagnostics features), but there have been
some complaints from people who have over 100 modules loaded
that this is a tad too slow.
This is due to the new backtracer code which looks at every
slot on the stack to see if it's a kernel/module text address,
so that's 1024 slots. 1024 times 100 modules... that's a lot
of list walking.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r-- | kernel/module.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/kernel/module.c b/kernel/module.c index 5c7eb0695b3c..d8b5605132a0 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -70,6 +70,9 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq); static BLOCKING_NOTIFIER_HEAD(module_notify_list); +/* Bounds of module allocation, for speeding __module_text_address */ +static unsigned long module_addr_min = -1UL, module_addr_max = 0; + int register_module_notifier(struct notifier_block * nb) { return blocking_notifier_chain_register(&module_notify_list, nb); @@ -1779,6 +1782,20 @@ static inline void add_kallsyms(struct module *mod, } #endif /* CONFIG_KALLSYMS */ +static void *module_alloc_update_bounds(unsigned long size) +{ + void *ret = module_alloc(size); + + if (ret) { + /* Update module bounds. */ + if ((unsigned long)ret < module_addr_min) + module_addr_min = (unsigned long)ret; + if ((unsigned long)ret + size > module_addr_max) + module_addr_max = (unsigned long)ret + size; + } + return ret; +} + /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ static struct module *load_module(void __user *umod, @@ -1980,7 +1997,7 @@ static struct module *load_module(void __user *umod, layout_sections(mod, hdr, sechdrs, secstrings); /* Do the allocs. */ - ptr = module_alloc(mod->core_size); + ptr = module_alloc_update_bounds(mod->core_size); if (!ptr) { err = -ENOMEM; goto free_percpu; @@ -1988,7 +2005,7 @@ static struct module *load_module(void __user *umod, memset(ptr, 0, mod->core_size); mod->module_core = ptr; - ptr = module_alloc(mod->init_size); + ptr = module_alloc_update_bounds(mod->init_size); if (!ptr && mod->init_size) { err = -ENOMEM; goto free_core; @@ -2645,6 +2662,9 @@ struct module *__module_text_address(unsigned long addr) { struct module *mod; + if (addr < module_addr_min || addr > module_addr_max) + return NULL; + list_for_each_entry(mod, &modules, list) if (within(addr, mod->module_init, mod->init_text_size) || within(addr, mod->module_core, mod->core_text_size)) |