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[RFC][PATCH 0/5] tracing: Allow module init functions to be traced

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  [RFC][PATCH 0/5] tracing: Allow module init functions to be traced Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200
    [RFC][PATCH 1/5] ftrace: Add a ftrace_free_mem() function for modules to use Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200
    [RFC][PATCH 4/5] ftrace: Add freeing algorithm to free ftrace_mod_maps Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200
    [RFC][PATCH 2/5] ftrace: Allow module init functions to be traced Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200
    [RFC][PATCH 3/5] ftrace: Save module init functions kallsyms symbols for tracing Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200
    [RFC][PATCH 5/5] ftrace/kallsyms: Have /proc/kallsyms show saved mod init functions Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 16:40 +0200

#1734955 — [RFC][PATCH 0/5] tracing: Allow module init functions to be traced

Last release, module functions can be enabled before they are loaded
by echoing in ":mod:module-name" into set_ftrace_filter before the
module is loaded. When the module is loaded, its functions will be
enabled for tracing. Now it makes sense to enable module init functions
as well (kernel init functions can already be traced).

The first patch adds a function ftrace_free_mem() to let module code
tell ftrace to free the init functions from its tables so that new
enabling or disabling of function tracing does not try to modify
text that no longer exists in memory.

The second patch enables tracing of init functions from within modules.

The third patch adds kallsyms of those init functions so they look
like funtion names and not function pointers within the trace.

The fourth patch frees the saved kallsym name maps of the function
names to the module init addresses.

The last patch has kallsyms display the module init functions.


Steven Rostedt (VMware) (5):
      ftrace: Add a ftrace_free_mem() function for modules to use
      ftrace: Allow module init functions to be traced
      ftrace: Save module init functions kallsyms symbols for tracing
      ftrace: Add freeing algorithm to free ftrace_mod_maps
      ftrace/kallsyms: Have /proc/kallsyms show saved mod init functions

----
 include/linux/ftrace.h |  26 ++++++
 include/linux/init.h   |   4 +-
 kernel/kallsyms.c      |  38 +++++++--
 kernel/module.c        |   2 +
 kernel/trace/ftrace.c  | 226 ++++++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 284 insertions(+), 12 deletions(-)

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#1734959 — [RFC][PATCH 1/5] ftrace: Add a ftrace_free_mem() function for modules to use

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

In order to be able to trace module init functions, the module code needs to
tell ftrace what is being freed when the init sections are freed. Use the
code that the main init calls to tell ftrace to free the main init sections.
This requires passing in a start and end address to free.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/ftrace.h |  2 ++
 kernel/trace/ftrace.c  | 14 +++++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 2e028854bac7..47fc404ad233 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -151,8 +151,10 @@ struct ftrace_ops_hash {
 };
 
 void ftrace_free_init_mem(void);
+void ftrace_free_mem(void *start, void *end);
 #else
 static inline void ftrace_free_init_mem(void) { }
+static inline void ftrace_free_mem(void *start, void *end) { }
 #endif
 
 /*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6abfafd7f173..84cb5928665a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5868,10 +5868,10 @@ void ftrace_module_init(struct module *mod)
 }
 #endif /* CONFIG_MODULES */
 
-void __init ftrace_free_init_mem(void)
+void ftrace_free_mem(void *start_ptr, void *end_ptr)
 {
-	unsigned long start = (unsigned long)(&__init_begin);
-	unsigned long end = (unsigned long)(&__init_end);
+	unsigned long start = (unsigned long)(start_ptr);
+	unsigned long end = (unsigned long)(end_ptr);
 	struct ftrace_page **last_pg = &ftrace_pages_start;
 	struct ftrace_page *pg;
 	struct dyn_ftrace *rec;
@@ -5913,6 +5913,14 @@ void __init ftrace_free_init_mem(void)
 	mutex_unlock(&ftrace_lock);
 }
 
+void __init ftrace_free_init_mem(void)
+{
+	void *start = (void *)(&__init_begin);
+	void *end = (void *)(&__init_end);
+
+	ftrace_free_mem(start, end);
+}
+
 void __init ftrace_init(void)
 {
 	extern unsigned long __start_mcount_loc[];
-- 
2.13.2

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#1734962 — [RFC][PATCH 4/5] ftrace: Add freeing algorithm to free ftrace_mod_maps

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

The ftrace_mod_map is a descriptor to save module init function names in
case they were traced, and the trace output needs to reference the function
name from the function address. But after the function is unloaded, it
the maps should be freed, as the rest of the function names are as well.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2aad52802d70..f0af3573b808 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5683,6 +5683,7 @@ struct ftrace_mod_func {
 };
 
 struct ftrace_mod_map {
+	struct rcu_head		rcu;
 	struct list_head	list;
 	struct module		*mod;
 	unsigned long		start_addr;
@@ -5694,6 +5695,8 @@ struct ftrace_mod_map {
 
 #define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next)
 
+static LIST_HEAD(ftrace_mod_maps);
+
 static int referenced_filters(struct dyn_ftrace *rec)
 {
 	struct ftrace_ops *ops;
@@ -5747,8 +5750,26 @@ static void clear_mod_from_hashes(struct ftrace_page *pg)
 	mutex_unlock(&trace_types_lock);
 }
 
+static void ftrace_free_mod_map(struct rcu_head *rcu)
+{
+	struct ftrace_mod_map *mod_map = container_of(rcu, struct ftrace_mod_map, rcu);
+	struct ftrace_mod_func *mod_func;
+	struct ftrace_mod_func *n;
+
+	/* All the contents of mod_map are now not visible to readers */
+	list_for_each_entry_safe(mod_func, n, &mod_map->funcs, list) {
+		kfree(mod_func->name);
+		list_del(&mod_func->list);
+		kfree(mod_func);
+	}
+
+	kfree(mod_map);
+}
+
 void ftrace_release_mod(struct module *mod)
 {
+	struct ftrace_mod_map *mod_map;
+	struct ftrace_mod_map *n;
 	struct dyn_ftrace *rec;
 	struct ftrace_page **last_pg;
 	struct ftrace_page *tmp_page = NULL;
@@ -5760,6 +5781,14 @@ void ftrace_release_mod(struct module *mod)
 	if (ftrace_disabled)
 		goto out_unlock;
 
+	list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
+		if (mod_map->mod == mod) {
+			list_del_rcu(&mod_map->list);
+			call_rcu_sched(&mod_map->rcu, ftrace_free_mod_map);
+			break;
+		}
+	}
+
 	/*
 	 * Each module has its own ftrace_pages, remove
 	 * them from the list.
@@ -5913,8 +5942,6 @@ static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
 	list_add_rcu(&mod_func->list, &mod_map->funcs);
 }
 
-static LIST_HEAD(ftrace_mod_maps);
-
 static struct ftrace_mod_map *
 allocate_ftrace_mod_map(struct module *mod,
 			unsigned long start, unsigned long end)
@@ -5973,6 +6000,7 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
 	struct ftrace_mod_map *mod_map;
 	const char *ret = NULL;
 
+	/* mod_map is freed via call_rcu_sched() */
 	preempt_disable();
 	list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
 		ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
-- 
2.13.2

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#1734964 — [RFC][PATCH 2/5] ftrace: Allow module init functions to be traced

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Allow for module init sections to be traced as well as core kernel init
sections. Now that filtering modules functions can be stored, for when they
are loaded, it makes sense to be able to trace them.

Cc: Jessica Yu <jeyu@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/init.h  | 4 +---
 kernel/module.c       | 2 ++
 kernel/trace/ftrace.c | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 94769d687cf0..a779c1816437 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -39,7 +39,7 @@
 
 /* These are for everybody (although not all archs will actually
    discard it in modules) */
-#define __init		__section(.init.text) __cold __inittrace __latent_entropy
+#define __init		__section(.init.text) __cold  __latent_entropy
 #define __initdata	__section(.init.data)
 #define __initconst	__section(.init.rodata)
 #define __exitdata	__section(.exit.data)
@@ -68,10 +68,8 @@
 
 #ifdef MODULE
 #define __exitused
-#define __inittrace notrace
 #else
 #define __exitused  __used
-#define __inittrace
 #endif
 
 #define __exit          __section(.exit.text) __exitused __cold notrace
diff --git a/kernel/module.c b/kernel/module.c
index 40f983cbea81..c1267ae10239 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3473,6 +3473,8 @@ static noinline int do_init_module(struct module *mod)
 	if (!mod->async_probe_requested && (current->flags & PF_USED_ASYNC))
 		async_synchronize_full();
 
+	ftrace_free_mem(mod->init_layout.base, mod->init_layout.base +
+			mod->init_layout.size);
 	mutex_lock(&module_mutex);
 	/* Drop initial reference. */
 	module_put(mod);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 84cb5928665a..7f7c56d532fd 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5821,7 +5821,8 @@ void ftrace_module_enable(struct module *mod)
 		 * not part of this module, then skip this pg,
 		 * which the "break" will do.
 		 */
-		if (!within_module_core(rec->ip, mod))
+		if (!within_module_core(rec->ip, mod) &&
+		    !within_module_init(rec->ip, mod))
 			break;
 
 		cnt = 0;
-- 
2.13.2

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#1734965 — [RFC][PATCH 3/5] ftrace: Save module init functions kallsyms symbols for tracing

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If function tracing is active when the module init functions are freed, then
store them to be referenced by kallsyms. As module init functions can now be
traced on module load, they were useless:

 ># echo ':mod:snd_seq' > set_ftrace_filter
 ># echo function > current_tracer
 ># modprobe snd_seq
 ># cat trace
 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
         modprobe-2786  [000] ....  3189.037874: 0xffffffffa0860000 <-do_one_initcall
         modprobe-2786  [000] ....  3189.037876: 0xffffffffa086004d <-0xffffffffa086000f
         modprobe-2786  [000] ....  3189.037876: 0xffffffffa086010d <-0xffffffffa0860018
         modprobe-2786  [000] ....  3189.037877: 0xffffffffa086011a <-0xffffffffa0860021
         modprobe-2786  [000] ....  3189.037877: 0xffffffffa0860080 <-0xffffffffa086002a
         modprobe-2786  [000] ....  3189.039523: 0xffffffffa0860400 <-0xffffffffa0860033
         modprobe-2786  [000] ....  3189.039523: 0xffffffffa086038a <-0xffffffffa086041c
         modprobe-2786  [000] ....  3189.039591: 0xffffffffa086038a <-0xffffffffa0860436
         modprobe-2786  [000] ....  3189.039657: 0xffffffffa086038a <-0xffffffffa0860450
         modprobe-2786  [000] ....  3189.039719: 0xffffffffa0860127 <-0xffffffffa086003c
         modprobe-2786  [000] ....  3189.039742: snd_seq_create_kernel_client <-0xffffffffa08601f6

When the output is shown, the kallsyms for the module init functions have
already been freed, and the output of the trace can not convert them to
their function names.

Now this looks like this:

 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
         modprobe-2463  [002] ....   174.243237: alsa_seq_init <-do_one_initcall
         modprobe-2463  [002] ....   174.243239: client_init_data <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_sequencer_memory_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_seq_queues_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_sequencer_device_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.244860: snd_seq_info_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.244861: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.244936: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.245003: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.245072: snd_seq_system_client_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.245094: snd_seq_create_kernel_client <-snd_seq_system_client_init

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/ftrace.h |  19 ++++++-
 kernel/kallsyms.c      |   5 ++
 kernel/module.c        |   2 +-
 kernel/trace/ftrace.c  | 145 ++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 166 insertions(+), 5 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 47fc404ad233..99b770228739 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -51,6 +51,21 @@ static inline void early_trace_init(void) { }
 struct module;
 struct ftrace_hash;
 
+#if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_MODULES) && \
+	defined(CONFIG_DYNAMIC_FTRACE)
+const char *
+ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
+		   unsigned long *off, char **modname, char *sym);
+#else
+static inline const char *
+ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
+		   unsigned long *off, char **modname, char *sym)
+{
+	return NULL;
+}
+#endif
+
+
 #ifdef CONFIG_FUNCTION_TRACER
 
 extern int ftrace_enabled;
@@ -151,10 +166,10 @@ struct ftrace_ops_hash {
 };
 
 void ftrace_free_init_mem(void);
-void ftrace_free_mem(void *start, void *end);
+void ftrace_free_mem(struct module *mod, void *start, void *end);
 #else
 static inline void ftrace_free_init_mem(void) { }
-static inline void ftrace_free_mem(void *start, void *end) { }
+static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { }
 #endif
 
 /*
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 127e7cfafa55..976ecb9275d9 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -24,6 +24,7 @@
 #include <linux/ctype.h>
 #include <linux/slab.h>
 #include <linux/filter.h>
+#include <linux/ftrace.h>
 #include <linux/compiler.h>
 
 #include <asm/sections.h>
@@ -337,6 +338,10 @@ const char *kallsyms_lookup(unsigned long addr,
 	if (!ret)
 		ret = bpf_address_lookup(addr, symbolsize,
 					 offset, modname, namebuf);
+
+	if (!ret)
+		ret = ftrace_mod_address_lookup(addr, symbolsize,
+						offset, modname, namebuf);
 	return ret;
 }
 
diff --git a/kernel/module.c b/kernel/module.c
index c1267ae10239..d0f48e402572 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3473,7 +3473,7 @@ static noinline int do_init_module(struct module *mod)
 	if (!mod->async_probe_requested && (current->flags & PF_USED_ASYNC))
 		async_synchronize_full();
 
-	ftrace_free_mem(mod->init_layout.base, mod->init_layout.base +
+	ftrace_free_mem(mod, mod->init_layout.base, mod->init_layout.base +
 			mod->init_layout.size);
 	mutex_lock(&module_mutex);
 	/* Drop initial reference. */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7f7c56d532fd..2aad52802d70 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5675,6 +5675,21 @@ static int ftrace_process_locs(struct module *mod,
 	return ret;
 }
 
+struct ftrace_mod_func {
+	struct list_head	list;
+	char			*name;
+	unsigned long		ip;
+	unsigned int		size;
+};
+
+struct ftrace_mod_map {
+	struct list_head	list;
+	struct module		*mod;
+	unsigned long		start_addr;
+	unsigned long		end_addr;
+	struct list_head	funcs;
+};
+
 #ifdef CONFIG_MODULES
 
 #define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next)
@@ -5867,9 +5882,122 @@ void ftrace_module_init(struct module *mod)
 	ftrace_process_locs(mod, mod->ftrace_callsites,
 			    mod->ftrace_callsites + mod->num_ftrace_callsites);
 }
+
+static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
+				struct dyn_ftrace *rec)
+{
+	struct ftrace_mod_func *mod_func;
+	unsigned long symsize;
+	unsigned long offset;
+	char str[KSYM_SYMBOL_LEN];
+	char *modname;
+	const char *ret;
+
+	ret = kallsyms_lookup(rec->ip, &symsize, &offset, &modname, str);
+	if (!ret)
+		return;
+
+	mod_func = kmalloc(sizeof(*mod_func), GFP_KERNEL);
+	if (!mod_func)
+		return;
+
+	mod_func->name = kstrdup(str, GFP_KERNEL);
+	if (!mod_func->name) {
+		kfree(mod_func);
+		return;
+	}
+
+	mod_func->ip = rec->ip - offset;
+	mod_func->size = symsize;
+
+	list_add_rcu(&mod_func->list, &mod_map->funcs);
+}
+
+static LIST_HEAD(ftrace_mod_maps);
+
+static struct ftrace_mod_map *
+allocate_ftrace_mod_map(struct module *mod,
+			unsigned long start, unsigned long end)
+{
+	struct ftrace_mod_map *mod_map;
+
+	mod_map = kmalloc(sizeof(*mod_map), GFP_KERNEL);
+	if (!mod_map)
+		return NULL;
+
+	mod_map->mod = mod;
+	mod_map->start_addr = start;
+	mod_map->end_addr = end;
+
+	INIT_LIST_HEAD_RCU(&mod_map->funcs);
+
+	list_add_rcu(&mod_map->list, &ftrace_mod_maps);
+
+	return mod_map;
+}
+
+static const char *
+ftrace_func_address_lookup(struct ftrace_mod_map *mod_map,
+			   unsigned long addr, unsigned long *size,
+			   unsigned long *off, char *sym)
+{
+	struct ftrace_mod_func *found_func =  NULL;
+	struct ftrace_mod_func *mod_func;
+
+	list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
+		if (addr >= mod_func->ip &&
+		    addr < mod_func->ip + mod_func->size) {
+			found_func = mod_func;
+			break;
+		}
+	}
+
+	if (found_func) {
+		if (size)
+			*size = found_func->size;
+		if (off)
+			*off = addr - found_func->ip;
+		if (sym)
+			strlcpy(sym, found_func->name, KSYM_NAME_LEN);
+
+		return found_func->name;
+	}
+
+	return NULL;
+}
+
+const char *
+ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
+		   unsigned long *off, char **modname, char *sym)
+{
+	struct ftrace_mod_map *mod_map;
+	const char *ret = NULL;
+
+	preempt_disable();
+	list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
+		ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
+		if (ret) {
+			if (modname)
+				*modname = mod_map->mod->name;
+			break;
+		}
+	}
+	preempt_enable();
+
+	return ret;
+}
+
+#else
+static inline void save_ftrace_mod_rec(struct dyn_ftrace *rec) { }
+static inline struct ftrace_mod_map *
+allocate_ftrace_mod_map(struct module *mod,
+			unsigned long start, unsigned long end)
+{
+	return NULL;
+}
 #endif /* CONFIG_MODULES */
 
-void ftrace_free_mem(void *start_ptr, void *end_ptr)
+void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr)
 {
 	unsigned long start = (unsigned long)(start_ptr);
 	unsigned long end = (unsigned long)(end_ptr);
@@ -5877,6 +6005,7 @@ void ftrace_free_mem(void *start_ptr, void *end_ptr)
 	struct ftrace_page *pg;
 	struct dyn_ftrace *rec;
 	struct dyn_ftrace key;
+	struct ftrace_mod_map *mod_map = NULL;
 	int order;
 
 	key.ip = start;
@@ -5884,6 +6013,14 @@ void ftrace_free_mem(void *start_ptr, void *end_ptr)
 
 	mutex_lock(&ftrace_lock);
 
+	/*
+	 * If we are freeing module init memory, then check if
+	 * any tracer is active. If so, we need to save a mapping of
+	 * the module functions being freed with the address.
+	 */
+	if (mod && ftrace_ops_list != &ftrace_list_end)
+		mod_map = allocate_ftrace_mod_map(mod, start, end);
+
 	for (pg = ftrace_pages_start; pg; last_pg = &pg->next, pg = *last_pg) {
 		if (end < pg->records[0].ip ||
 		    start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
@@ -5894,6 +6031,10 @@ void ftrace_free_mem(void *start_ptr, void *end_ptr)
 			      ftrace_cmp_recs);
 		if (!rec)
 			continue;
+
+		if (mod_map)
+			save_ftrace_mod_rec(mod_map, rec);
+
 		pg->index--;
 		ftrace_update_tot_cnt--;
 		if (!pg->index) {
@@ -5919,7 +6060,7 @@ void __init ftrace_free_init_mem(void)
 	void *start = (void *)(&__init_begin);
 	void *end = (void *)(&__init_end);
 
-	ftrace_free_mem(start, end);
+	ftrace_free_mem(NULL, start, end);
 }
 
 void __init ftrace_init(void)
-- 
2.13.2

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#1734966 — [RFC][PATCH 5/5] ftrace/kallsyms: Have /proc/kallsyms show saved mod init functions

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If a module is loaded while tracing is enabled, then there's a possibility
that the module init functions were traced. These functions have their name
and address stored by ftrace such that it can translate the function address
that is written into the buffer into a human readable function name.

As userspace tools may be doing the same, they need a way to map function
names to their address as well. This is done through reading /proc/kallsyms.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/ftrace.h |  9 +++++++++
 kernel/kallsyms.c      | 33 ++++++++++++++++++++++++++++-----
 kernel/trace/ftrace.c  | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+), 5 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 99b770228739..3bfafeff26cc 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -56,6 +56,9 @@ struct ftrace_hash;
 const char *
 ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
 		   unsigned long *off, char **modname, char *sym);
+int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
+			   char *type, char *name,
+			   char *module_name, int *exported);
 #else
 static inline const char *
 ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
@@ -63,6 +66,12 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
 {
 	return NULL;
 }
+static inline int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
+					 char *type, char *name,
+					 char *module_name, int *exported)
+{
+	return 0;
+}
 #endif
 
 
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 976ecb9275d9..97983dc1555c 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -479,6 +479,7 @@ EXPORT_SYMBOL(__print_symbol);
 struct kallsym_iter {
 	loff_t pos;
 	loff_t pos_mod_end;
+	loff_t pos_ftrace_mod_end;
 	unsigned long value;
 	unsigned int nameoff; /* If iterating in core kernel symbols. */
 	char type;
@@ -501,11 +502,25 @@ static int get_ksymbol_mod(struct kallsym_iter *iter)
 	return 1;
 }
 
+static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
+{
+	int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
+					 &iter->value, &iter->type,
+					 iter->name, iter->module_name,
+					 &iter->exported);
+	if (ret < 0) {
+		iter->pos_ftrace_mod_end = iter->pos;
+		return 0;
+	}
+
+	return 1;
+}
+
 static int get_ksymbol_bpf(struct kallsym_iter *iter)
 {
 	iter->module_name[0] = '\0';
 	iter->exported = 0;
-	return bpf_get_kallsym(iter->pos - iter->pos_mod_end,
+	return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
 			       &iter->value, &iter->type,
 			       iter->name) < 0 ? 0 : 1;
 }
@@ -530,20 +545,28 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
 	iter->name[0] = '\0';
 	iter->nameoff = get_symbol_offset(new_pos);
 	iter->pos = new_pos;
-	if (new_pos == 0)
+	if (new_pos == 0) {
 		iter->pos_mod_end = 0;
+		iter->pos_ftrace_mod_end = 0;
+	}
 }
 
 static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
 {
 	iter->pos = pos;
 
+	if (iter->pos_ftrace_mod_end > 0 &&
+	    iter->pos_ftrace_mod_end < iter->pos)
+		return get_ksymbol_bpf(iter);
+
 	if (iter->pos_mod_end > 0 &&
 	    iter->pos_mod_end < iter->pos)
-		return get_ksymbol_bpf(iter);
+		return get_ksymbol_ftrace_mod(iter);
 
-	if (!get_ksymbol_mod(iter))
-		return get_ksymbol_bpf(iter);
+	if (!get_ksymbol_mod(iter)) {
+		if (!get_ksymbol_ftrace_mod(iter))
+			return get_ksymbol_bpf(iter);
+	}
 
 	return 1;
 }
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f0af3573b808..fabf315b9cb1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5689,6 +5689,7 @@ struct ftrace_mod_map {
 	unsigned long		start_addr;
 	unsigned long		end_addr;
 	struct list_head	funcs;
+	unsigned int		num_funcs;
 };
 
 #ifdef CONFIG_MODULES
@@ -5939,6 +5940,8 @@ static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
 	mod_func->ip = rec->ip - offset;
 	mod_func->size = symsize;
 
+	mod_map->num_funcs++;
+
 	list_add_rcu(&mod_func->list, &mod_map->funcs);
 }
 
@@ -5955,6 +5958,7 @@ allocate_ftrace_mod_map(struct module *mod,
 	mod_map->mod = mod;
 	mod_map->start_addr = start;
 	mod_map->end_addr = end;
+	mod_map->num_funcs = 0;
 
 	INIT_LIST_HEAD_RCU(&mod_map->funcs);
 
@@ -6015,6 +6019,42 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
 	return ret;
 }
 
+int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
+			   char *type, char *name,
+			   char *module_name, int *exported)
+{
+	struct ftrace_mod_map *mod_map;
+	struct ftrace_mod_func *mod_func;
+
+	preempt_disable();
+	list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
+
+		if (symnum >= mod_map->num_funcs) {
+			symnum -= mod_map->num_funcs;
+			continue;
+		}
+
+		list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
+			if (symnum > 1) {
+				symnum--;
+				continue;
+			}
+
+			*value = mod_func->ip;
+			*type = 'T';
+			strlcpy(name, mod_func->name, KSYM_NAME_LEN);
+			strlcpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
+			*exported = 1;
+			preempt_enable();
+			return 0;
+		}
+		WARN_ON(1);
+		break;
+	}
+	preempt_enable();
+	return -ERANGE;
+}
+
 #else
 static inline void save_ftrace_mod_rec(struct dyn_ftrace *rec) { }
 static inline struct ftrace_mod_map *
-- 
2.13.2

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