| From a79b5cdfc5a94b238deb2d1041b85da23fe0e4a6 Mon Sep 17 00:00:00 2001 |
| From: Peter Zijlstra <peterz@infradead.org> |
| Date: Thu, 7 Mar 2019 11:09:13 +0100 |
| Subject: x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP |
| |
| [ Upstream commit 4a6c91fbdef846ec7250b82f2eeeb87ac5f18cf9 ] |
| |
| For CONFIG_TRACE_BRANCH_PROFILING=y the likely/unlikely things get |
| overloaded and generate callouts to this code, and thus also when |
| AC=1. |
| |
| Make it safe. |
| |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: Josh Poimboeuf <jpoimboe@redhat.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Steven Rostedt <rostedt@goodmis.org> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| kernel/trace/trace_branch.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c |
| index 4ad967453b6fb..3ea65cdff30d5 100644 |
| --- a/kernel/trace/trace_branch.c |
| +++ b/kernel/trace/trace_branch.c |
| @@ -205,6 +205,8 @@ void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) |
| void ftrace_likely_update(struct ftrace_likely_data *f, int val, |
| int expect, int is_constant) |
| { |
| + unsigned long flags = user_access_save(); |
| + |
| /* A constant is always correct */ |
| if (is_constant) { |
| f->constant++; |
| @@ -223,6 +225,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, |
| f->data.correct++; |
| else |
| f->data.incorrect++; |
| + |
| + user_access_restore(flags); |
| } |
| EXPORT_SYMBOL(ftrace_likely_update); |
| |
| -- |
| 2.20.1 |
| |