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authorSteven Rostedt <rostedt@goodmis.org>2008-08-14 22:47:19 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-14 10:35:12 +0200
commitfed1939c64d2288938fdc1c367d49082da65e195 (patch)
treea4592352d28efcfe82379c71d061b9127e49a115
parent28614889bcb2558a47d02d52394b7fd9795a9547 (diff)
downloadop-kernel-dev-fed1939c64d2288938fdc1c367d49082da65e195.zip
op-kernel-dev-fed1939c64d2288938fdc1c367d49082da65e195.tar.gz
ftrace: remove old pointers to mcount
When a mcount pointer is recorded into a table, it is used to add or remove calls to mcount (replacing them with nops). If the code is removed via removing a module, the pointers still exist. At modifying the code a check is always made to make sure the code being replaced is the code expected. In-other-words, the code being replaced is compared to what it is expected to be before being replaced. There is a very small chance that the code being replaced just happens to look like code that calls mcount (very small since the call to mcount is relative). To remove this chance, this patch adds ftrace_release to allow module unloading to remove the pointers to mcount within the module. Another change for init calls is made to not trace calls marked with __init. The tracing can not be started until after init is done anyway. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/ftrace.h2
-rw-r--r--include/linux/init.h2
-rw-r--r--kernel/module.c12
-rw-r--r--kernel/trace/ftrace.c32
4 files changed, 41 insertions, 7 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 4936489..6b232a2 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -165,10 +165,12 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
extern void ftrace_init_module(unsigned long *start, unsigned long *end);
+extern void ftrace_release(void *start, unsigned long size);
#else
static inline void ftrace_init(void) { }
static inline void
ftrace_init_module(unsigned long *start, unsigned long *end) { }
+static inline void ftrace_release(void *start, unsigned long size) { }
#endif
#endif /* _LINUX_FTRACE_H */
diff --git a/include/linux/init.h b/include/linux/init.h
index 93538b6..27f61f6 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -40,7 +40,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
-#define __init __section(.init.text) __cold
+#define __init __section(.init.text) __cold notrace
#define __initdata __section(.init.data)
#define __initconst __section(.init.rodata)
#define __exitdata __section(.exit.data)
diff --git a/kernel/module.c b/kernel/module.c
index d753fd9..7576c2d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1431,6 +1431,9 @@ static void free_module(struct module *mod)
/* Module unload stuff */
module_unload_free(mod);
+ /* release any pointers to mcount in this module */
+ ftrace_release(mod->module_core, mod->core_size);
+
/* This may be NULL, but that's OK */
module_free(mod, mod->module_init);
kfree(mod->args);
@@ -1839,6 +1842,7 @@ static noinline struct module *load_module(void __user *umod,
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
+ void *mseg;
struct exception_table_entry *extable;
mm_segment_t old_fs;
@@ -2190,10 +2194,9 @@ static noinline struct module *load_module(void __user *umod,
#endif
}
- if (mcountindex) {
- void *mseg = (void *)sechdrs[mcountindex].sh_addr;
- ftrace_init_module(mseg, mseg + sechdrs[mcountindex].sh_size);
- }
+ /* sechdrs[0].sh_size is always zero */
+ mseg = (void *)sechdrs[mcountindex].sh_addr;
+ ftrace_init_module(mseg, mseg + sechdrs[mcountindex].sh_size);
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
@@ -2264,6 +2267,7 @@ static noinline struct module *load_module(void __user *umod,
cleanup:
kobject_del(&mod->mkobj.kobj);
kobject_put(&mod->mkobj.kobj);
+ ftrace_release(mod->module_core, mod->core_size);
free_unload:
module_unload_free(mod);
module_free(mod, mod->module_init);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8affb6d..eadd0ea 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -294,13 +294,37 @@ static inline void ftrace_del_hash(struct dyn_ftrace *node)
static void ftrace_free_rec(struct dyn_ftrace *rec)
{
- /* no locking, only called from kstop_machine */
-
rec->ip = (unsigned long)ftrace_free_records;
ftrace_free_records = rec;
rec->flags |= FTRACE_FL_FREE;
}
+void ftrace_release(void *start, unsigned long size)
+{
+ struct dyn_ftrace *rec;
+ struct ftrace_page *pg;
+ unsigned long s = (unsigned long)start;
+ unsigned long e = s + size;
+ int i;
+
+ if (!start)
+ return;
+
+ /* No interrupt should call this */
+ spin_lock(&ftrace_lock);
+
+ for (pg = ftrace_pages_start; pg; pg = pg->next) {
+ for (i = 0; i < pg->index; i++) {
+ rec = &pg->records[i];
+
+ if ((rec->ip >= s) && (rec->ip < e))
+ ftrace_free_rec(rec);
+ }
+ }
+ spin_unlock(&ftrace_lock);
+
+}
+
static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
{
struct dyn_ftrace *rec;
@@ -1527,7 +1551,9 @@ static int ftrace_convert_nops(unsigned long *start,
p = start;
while (p < end) {
addr = ftrace_call_adjust(*p++);
+ spin_lock(&ftrace_lock);
ftrace_record_ip(addr);
+ spin_unlock(&ftrace_lock);
ftrace_shutdown_replenish();
}
@@ -1541,6 +1567,8 @@ static int ftrace_convert_nops(unsigned long *start,
void ftrace_init_module(unsigned long *start, unsigned long *end)
{
+ if (start == end)
+ return;
ftrace_convert_nops(start, end);
}
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