[GIT PULL] tracing: More fixes for 5.5

From: Steven Rostedt
Date: Wed Dec 11 2019 - 09:42:55 EST


Linus,

This contains 3 changes:

- Removal of code I accidentally applied when doing a minor fix up
to a patch, and then using "git commit -a --amend", which pulled
in some other changes I was playing with.

- Remove an used variable in trace_events_inject code

- Fix to function graph tracer when it traces a ftrace direct function.
It will now ignore tracing a function that has a ftrace direct
tramploine attached. This is needed for eBPF to use the ftrace direct
code.

Please pull the latest trace-v5.5-3 tree, which can be found at:


git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.5-3

Tag SHA1: 2f96b90660986979a6bbca1e8738b9aeb5e7eeff
Head SHA1: ff205766dbbee024a4a716638868d98ffb17748a


Alexei Starovoitov (1):
ftrace: Fix function_graph tracer interaction with BPF trampoline

Steven Rostedt (VMware) (1):
module: Remove accidental change of module_enable_x()

YueHaibing (1):
tracing: remove set but not used variable 'buffer'

----
arch/x86/kernel/ftrace.c | 14 --------------
include/linux/ftrace.h | 5 +++++
kernel/module.c | 6 +-----
kernel/trace/fgraph.c | 9 +++++++++
kernel/trace/ftrace.c | 19 +++++++------------
kernel/trace/trace_events_inject.c | 2 --
6 files changed, 22 insertions(+), 33 deletions(-)
---------------------------
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 060a361d9d11..024c3053dbba 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -1042,20 +1042,6 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
if (unlikely(atomic_read(&current->tracing_graph_pause)))
return;

- /*
- * If the return location is actually pointing directly to
- * the start of a direct trampoline (if we trace the trampoline
- * it will still be offset by MCOUNT_INSN_SIZE), then the
- * return address is actually off by one word, and we
- * need to adjust for that.
- */
- if (ftrace_direct_func_count) {
- if (ftrace_find_direct_func(self_addr + MCOUNT_INSN_SIZE)) {
- self_addr = *parent;
- parent++;
- }
- }
-
/*
* Protect against fault, even if it shouldn't
* happen. This tool is too much intrusive to
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 232806d5689d..987c2dc55bde 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -264,6 +264,7 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
struct dyn_ftrace *rec,
unsigned long old_addr,
unsigned long new_addr);
+unsigned long ftrace_find_rec_direct(unsigned long ip);
#else
# define ftrace_direct_func_count 0
static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
@@ -290,6 +291,10 @@ static inline int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
{
return -ENODEV;
}
+static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
+{
+ return 0;
+}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
diff --git a/kernel/module.c b/kernel/module.c
index 6e2fd40a6ed9..ff2d7359a418 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3728,6 +3728,7 @@ static int complete_formation(struct module *mod, struct load_info *info)

module_enable_ro(mod, false);
module_enable_nx(mod);
+ module_enable_x(mod);

/* Mark state as coming so strong_try_module_get() ignores us,
* but kallsyms etc. can see us. */
@@ -3750,11 +3751,6 @@ static int prepare_coming_module(struct module *mod)
if (err)
return err;

- /* Make module executable after ftrace is enabled */
- mutex_lock(&module_mutex);
- module_enable_x(mod);
- mutex_unlock(&module_mutex);
-
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
return 0;
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 67e0c462b059..a2659735db73 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -101,6 +101,15 @@ int function_graph_enter(unsigned long ret, unsigned long func,
{
struct ftrace_graph_ent trace;

+ /*
+ * Skip graph tracing if the return location is served by direct trampoline,
+ * since call sequence and return addresses is unpredicatable anymore.
+ * Ex: BPF trampoline may call original function and may skip frame
+ * depending on type of BPF programs attached.
+ */
+ if (ftrace_direct_func_count &&
+ ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE))
+ return -EBUSY;
trace.func = func;
trace.depth = ++current->curr_ret_depth;

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index caae523f4ef3..57477dc683db 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2364,7 +2364,7 @@ int ftrace_direct_func_count;
* Search the direct_functions hash to see if the given instruction pointer
* has a direct caller attached to it.
*/
-static unsigned long find_rec_direct(unsigned long ip)
+unsigned long ftrace_find_rec_direct(unsigned long ip)
{
struct ftrace_func_entry *entry;

@@ -2380,7 +2380,7 @@ static void call_direct_funcs(unsigned long ip, unsigned long pip,
{
unsigned long addr;

- addr = find_rec_direct(ip);
+ addr = ftrace_find_rec_direct(ip);
if (!addr)
return;

@@ -2393,11 +2393,6 @@ struct ftrace_ops direct_ops = {
| FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS
| FTRACE_OPS_FL_PERMANENT,
};
-#else
-static inline unsigned long find_rec_direct(unsigned long ip)
-{
- return 0;
-}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

/**
@@ -2417,7 +2412,7 @@ unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)

if ((rec->flags & FTRACE_FL_DIRECT) &&
(ftrace_rec_count(rec) == 1)) {
- addr = find_rec_direct(rec->ip);
+ addr = ftrace_find_rec_direct(rec->ip);
if (addr)
return addr;
WARN_ON_ONCE(1);
@@ -2458,7 +2453,7 @@ unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec)

/* Direct calls take precedence over trampolines */
if (rec->flags & FTRACE_FL_DIRECT_EN) {
- addr = find_rec_direct(rec->ip);
+ addr = ftrace_find_rec_direct(rec->ip);
if (addr)
return addr;
WARN_ON_ONCE(1);
@@ -3604,7 +3599,7 @@ static int t_show(struct seq_file *m, void *v)
if (rec->flags & FTRACE_FL_DIRECT) {
unsigned long direct;

- direct = find_rec_direct(rec->ip);
+ direct = ftrace_find_rec_direct(rec->ip);
if (direct)
seq_printf(m, "\n\tdirect-->%pS", (void *)direct);
}
@@ -5008,7 +5003,7 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
mutex_lock(&direct_mutex);

/* See if there's a direct function at @ip already */
- if (find_rec_direct(ip))
+ if (ftrace_find_rec_direct(ip))
goto out_unlock;

ret = -ENODEV;
@@ -5027,7 +5022,7 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
if (ip != rec->ip) {
ip = rec->ip;
/* Need to check this ip for a direct. */
- if (find_rec_direct(ip))
+ if (ftrace_find_rec_direct(ip))
goto out_unlock;
}

diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c
index d43710718ee5..d45079ee62f8 100644
--- a/kernel/trace/trace_events_inject.c
+++ b/kernel/trace/trace_events_inject.c
@@ -17,12 +17,10 @@ static int
trace_inject_entry(struct trace_event_file *file, void *rec, int len)
{
struct trace_event_buffer fbuffer;
- struct ring_buffer *buffer;
int written = 0;
void *entry;

rcu_read_lock_sched();
- buffer = file->tr->trace_buffer.buffer;
entry = trace_event_buffer_reserve(&fbuffer, file, len);
if (entry) {
memcpy(entry, rec, len);