Commit 6c9692e2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Rusty Russell

module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING

Andrew worried about the overhead on small systems; only use the fancy
code when either perf or tracing is enabled.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Requested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 93c2e105
......@@ -282,7 +282,7 @@ struct module {
*
* Cacheline align here, such that:
* module_init, module_core, init_size, core_size,
* init_text_size, core_text_size and ltn_core.node[0]
* init_text_size, core_text_size and mtn_core::{mod,node[0]}
* are on the same cacheline.
*/
void *module_init ____cacheline_aligned;
......@@ -296,6 +296,7 @@ struct module {
/* The size of the executable code in each section. */
unsigned int init_text_size, core_text_size;
#ifdef CONFIG_MODULES_TREE_LOOKUP
/*
* We want mtn_core::{mod,node[0]} to be in the same cacheline as the
* above entries such that a regular lookup will only touch one
......@@ -303,6 +304,7 @@ struct module {
*/
struct mod_tree_node mtn_core;
struct mod_tree_node mtn_init;
#endif
/* Size of RO sections of the module (text+rodata) */
unsigned int init_ro_size, core_ro_size;
......
......@@ -1989,6 +1989,10 @@ endchoice
endif # MODULES
config MODULES_TREE_LOOKUP
def_bool y
depends on PERF_EVENTS || TRACING
config INIT_ALL_POSSIBLE
bool
help
......
......@@ -102,6 +102,8 @@ DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);
#ifdef CONFIG_MODULES_TREE_LOOKUP
/*
* Use a latched RB-tree for __module_address(); this allows us to use
* RCU-sched lookups of the address from any context.
......@@ -112,6 +114,10 @@ static LIST_HEAD(modules);
*
* Because init ranges are short lived we mark them unlikely and have placed
* them outside the critical cacheline in struct module.
*
* This is conditional on PERF_EVENTS || TRACING because those can really hit
* __module_address() hard by doing a lot of stack unwinding; potentially from
* NMI context.
*/
static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
......@@ -192,7 +198,7 @@ static void mod_tree_remove(struct module *mod)
mod_tree_remove_init(mod);
}
static struct module *mod_tree_find(unsigned long addr)
static struct module *mod_find(unsigned long addr)
{
struct latch_tree_node *ltn;
......@@ -203,6 +209,26 @@ static struct module *mod_tree_find(unsigned long addr)
return container_of(ltn, struct mod_tree_node, node)->mod;
}
#else /* MODULES_TREE_LOOKUP */
static void mod_tree_insert(struct module *mod) { }
static void mod_tree_remove_init(struct module *mod) { }
static void mod_tree_remove(struct module *mod) { }
static struct module *mod_find(unsigned long addr)
{
struct module *mod;
list_for_each_entry_rcu(mod, &modules, list) {
if (within_module(addr, mod))
return mod;
}
return NULL;
}
#endif /* MODULES_TREE_LOOKUP */
#ifdef CONFIG_KGDB_KDB
struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
#endif /* CONFIG_KGDB_KDB */
......@@ -3966,7 +3992,7 @@ struct module *__module_address(unsigned long addr)
module_assert_mutex_or_preempt();
mod = mod_tree_find(addr);
mod = mod_find(addr);
if (mod) {
BUG_ON(!within_module(addr, mod));
if (mod->state == MODULE_STATE_UNFORMED)
......
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