From af74262337faa65d5ac2944553437d3f5fb29123 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Mon, 9 Dec 2019 10:33:30 -0500 Subject: [PATCH 1/3] module: Remove accidental change of module_enable_x() When pulling in Divya Indi's patch, I made a minor fix to remove unneeded braces. I commited my fix up via "git commit -a --amend". Unfortunately, I didn't realize I had some changes I was testing in the module code, and those changes were applied to Divya's patch as well. This reverts the accidental updates to the module code. Cc: Jessica Yu Cc: Divya Indi Reported-by: Peter Zijlstra Fixes: e585e6469d6f ("tracing: Verify if trace array exists before destroying it.") Signed-off-by: Steven Rostedt (VMware) --- kernel/module.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) 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; From a61f810567be0ef101d8bbb65b89ffeac7d62103 Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Sat, 7 Dec 2019 11:44:09 +0800 Subject: [PATCH 2/3] tracing: remove set but not used variable 'buffer' kernel/trace/trace_events_inject.c: In function trace_inject_entry: kernel/trace/trace_events_inject.c:20:22: warning: variable buffer set but not used [-Wunused-but-set-variable] It is never used, so remove it. Link: http://lkml.kernel.org/r/20191207034409.25668-1-yuehaibing@huawei.com Reported-by: Hulk Robot Acked-by: Cong Wang Signed-off-by: YueHaibing Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_inject.c | 2 -- 1 file changed, 2 deletions(-) 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); From ff205766dbbee024a4a716638868d98ffb17748a Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Sun, 8 Dec 2019 16:01:12 -0800 Subject: [PATCH 3/3] ftrace: Fix function_graph tracer interaction with BPF trampoline Depending on type of BPF programs served by BPF trampoline it can call original function. In such case the trampoline will skip one stack frame while returning. That will confuse function_graph tracer and will cause crashes with bad RIP. Teach graph tracer to skip functions that have BPF trampoline attached. Signed-off-by: Alexei Starovoitov Signed-off-by: Steven Rostedt (VMware) --- arch/x86/kernel/ftrace.c | 14 -------------- include/linux/ftrace.h | 5 +++++ kernel/trace/fgraph.c | 9 +++++++++ kernel/trace/ftrace.c | 19 +++++++------------ 4 files changed, 21 insertions(+), 26 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(¤t->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/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; }