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SubjectRe: [PATCH] tracing/profile: Fix profile_disable vs module_unload
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On Wed, 2009-08-26 at 08:46 +0200, Peter Zijlstra wrote:

> Aahh, I see the bug, its only ftrace that knows about the module, not
> tracepoints themselves, _that_ needs fixing.

These are the bits I hacked up until I figured out the above bug.

---
include/linux/ftrace_event.h | 2 +-
include/linux/module.h | 18 ++++++++++++++----
kernel/module.c | 9 +--------
3 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index df5b085..d86d60c 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -122,7 +122,7 @@ struct ftrace_event_call {
struct list_head fields;
int filter_active;
struct event_filter *filter;
- void *mod;
+ struct module *mod;
void *data;

atomic_t profile_count;
diff --git a/include/linux/module.h b/include/linux/module.h
index 86863cd..09e2b88 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -409,16 +409,26 @@ struct module *__module_address(unsigned long addr);
bool is_module_address(unsigned long addr);
bool is_module_text_address(unsigned long addr);

+static inline
+int __within_module(unsigned long addr, void *start, unsigned long size)
+{
+ return ((void *)addr >= start && (void *)addr < start + size);
+}
+
static inline int within_module_core(unsigned long addr, struct module *mod)
{
- return (unsigned long)mod->module_core <= addr &&
- addr < (unsigned long)mod->module_core + mod->core_size;
+ return __within_module(addr, mod->module_core, mod->core_size);
}

static inline int within_module_init(unsigned long addr, struct module *mod)
{
- return (unsigned long)mod->module_init <= addr &&
- addr < (unsigned long)mod->module_init + mod->init_size;
+ return __within_module(addr, mod->module_init, mod->init_size);
+}
+
+static inline int within_module_text(unsigned long addr, struct module *mod)
+{
+ return __within_module(addr, mod->module_init, mod->init_text_size) ||
+ __within_module(addr, mod->core_init, mod->core_text_size);
}

/* Search for module by name: must hold module_mutex. */
diff --git a/kernel/module.c b/kernel/module.c
index b182143..822adb6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2493,11 +2493,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
return 0;
}

-static inline int within(unsigned long addr, void *start, unsigned long size)
-{
- return ((void *)addr >= start && (void *)addr < start + size);
-}
-
#ifdef CONFIG_KALLSYMS
/*
* This ignores the intensely annoying "mapping symbols" found
@@ -2912,9 +2907,7 @@ struct module *__module_text_address(unsigned long addr)
{
struct module *mod = __module_address(addr);
if (mod) {
- /* Make sure it's within the text section. */
- if (!within(addr, mod->module_init, mod->init_text_size)
- && !within(addr, mod->module_core, mod->core_text_size))
+ if (!within_module_text(addr, mod))
mod = NULL;
}
return mod;


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