Commit 4a6c91fb authored Mar 07, 2019 by Peter Zijlstra Committed by Ingo Molnar Apr 03, 2019

x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP



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>

parent d08965a2

kernel/trace/trace_branch.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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);

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