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Subject[tip:locking/core] jump_label: Add a jump_label_can_update() helper
Commit-ID:  e1aacb3f4adc1bcd4273a1d538a2dc3e50f1cbb5
Gitweb: https://git.kernel.org/tip/e1aacb3f4adc1bcd4273a1d538a2dc3e50f1cbb5
Author: Daniel Bristot de Oliveira <bristot@redhat.com>
AuthorDate: Wed, 12 Jun 2019 11:57:26 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 17 Jun 2019 12:09:19 +0200

jump_label: Add a jump_label_can_update() helper

Move the check if a jump_entry is valid to a function. No functional
change.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/56b69bd3f8e644ed64f2dbde7c088030b8cbe76b.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/jump_label.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0bfa10f4410c..24f0d3b1526b 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -384,23 +384,30 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry)
return enabled ^ branch;
}

+static bool jump_label_can_update(struct jump_entry *entry, bool init)
+{
+ /*
+ * Cannot update code that was in an init text area.
+ */
+ if (!init && jump_entry_is_init(entry))
+ return false;
+
+ if (!kernel_text_address(jump_entry_code(entry))) {
+ WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry));
+ return false;
+ }
+
+ return true;
+}
+
static void __jump_label_update(struct static_key *key,
struct jump_entry *entry,
struct jump_entry *stop,
bool init)
{
for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
- /*
- * An entry->code of 0 indicates an entry which has been
- * disabled because it was in an init text area.
- */
- if (init || !jump_entry_is_init(entry)) {
- if (kernel_text_address(jump_entry_code(entry)))
- arch_jump_label_transform(entry, jump_label_type(entry));
- else
- WARN_ONCE(1, "can't patch jump_label at %pS",
- (void *)jump_entry_code(entry));
- }
+ if (jump_label_can_update(entry, init))
+ arch_jump_label_transform(entry, jump_label_type(entry));
}
}

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