[PATCH 05/13] kallsyms: refactor {,module_}kallsyms_on_each_symbol

Christoph Hellwig
2021-01-21T20:10:18Z

Require an explicit cll to module_kallsyms_on_each_symbol to look
for symbols in modules instead of the call from kallsyms_on_each_symbol,
and acquire module_mutex inside of module_kallsyms_on_each_symbol instead
of leaving that up to the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
kernel/kallsyms.c | 6 +++++-
kernel/livepatch/core.c | 6 +-----
kernel/module.c | 8 ++++----
3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index fe9de067771c34..a0d3f0865916f9 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -177,6 +177,10 @@ unsigned long kallsyms_lookup_name(const char *name)
return module_kallsyms_lookup_name(name);
}

+/*
+ * Iterate over all symbols in vmlinux. For symbols from modules use
+ * module_kallsyms_on_each_symbol instead.
+ */
int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
unsigned long),
void *data)
@@ -192,7 +196,7 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
if (ret != 0)
return ret;
}
- return module_kallsyms_on_each_symbol(fn, data);
+ return 0;
}

static unsigned long get_symbol_pos(unsigned long addr,
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 878759baadd81c..8063b9089bd2f8 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -135,12 +135,8 @@ static int klp_find_object_symbol(const char *objname, const char *name,
.pos = sympos,
};

- mutex_lock(&module_mutex);
- if (objname)
+ if (objname || !kallsyms_on_each_symbol(klp_find_callback, &args))
module_kallsyms_on_each_symbol(klp_find_callback, &args);
- else
- kallsyms_on_each_symbol(klp_find_callback, &args);
- mutex_unlock(&module_mutex);

/*
* Ensure an address was found. If sympos is 0, ensure symbol is unique;
diff --git a/kernel/module.c b/kernel/module.c
index 299cbac0775cf2..885feec64c1b6f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4407,8 +4407,7 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
unsigned int i;
int ret;

- module_assert_mutex();
-
+ mutex_lock(&module_mutex);
list_for_each_entry(mod, &modules, list) {
/* We hold module_mutex: no need for rcu_dereference_sched */
struct mod_kallsyms *kallsyms = mod->kallsyms;
@@ -4424,10 +4423,11 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
ret = fn(data, kallsyms_symbol_name(kallsyms, i),
mod, kallsyms_symbol_value(sym));
if (ret != 0)
- return ret;
+ break;
}
}
- return 0;
+ mutex_unlock(&module_mutex);
+ return ret;
}
#endif /* CONFIG_KALLSYMS */

--
2.29.2