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Subject[RFC PATCH 3/6] x86/jump_label: Move checking code away from __jump_label_transform()
Date
This patch creates two new functions, __jump_label_enabling_check()
and __jump_label_disabling_check(), to make the respective check before
updating a jump_entry.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Zhou Chengming <zhouchengming1@huawei.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Scott Wood <swood@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
---
arch/x86/kernel/jump_label.c | 88 ++++++++++++++++++++++--------------
1 file changed, 53 insertions(+), 35 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index eeea935e9bb5..a11d836d9aaa 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -37,57 +37,75 @@ static void bug_at(unsigned char *ip, int line)
BUG();
}

+static inline void __jump_label_enabling_check(struct jump_entry *entry,
+ enum jump_label_type type,
+ int init)
+{
+ const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
+ const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
+
+ if (init) {
+ /*
+ * Jump label is enabled for the first time.
+ * So we expect a default_nop...
+ */
+ if (unlikely(memcmp((void *)entry->code, default_nop, 5)
+ != 0))
+ bug_at((void *)entry->code, __LINE__);
+ } else {
+ /*
+ * ...otherwise expect an ideal_nop. Otherwise
+ * something went horribly wrong.
+ */
+ if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)
+ != 0))
+ bug_at((void *)entry->code, __LINE__);
+ }
+}
+
+static inline void __jump_label_disabling_check(struct jump_entry *entry,
+ enum jump_label_type type,
+ int init)
+{
+ union jump_code_union code;
+ const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
+
+ /*
+ * We are disabling this jump label. If it is not what
+ * we think it is, then something must have gone wrong.
+ * If this is the first initialization call, then we
+ * are converting the default nop to the ideal nop.
+ */
+ if (init) {
+ if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))
+ bug_at((void *)entry->code, __LINE__);
+ } else {
+ code.jump = 0xe9;
+ code.offset = entry->target -
+ (entry->code + JUMP_LABEL_NOP_SIZE);
+ if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))
+ bug_at((void *)entry->code, __LINE__);
+ }
+}
+
static void __ref __jump_label_transform(struct jump_entry *entry,
enum jump_label_type type,
void *(*poker)(void *, const void *, size_t),
int init)
{
union jump_code_union code;
- const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
- const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];

if (early_boot_irqs_disabled)
poker = text_poke_early;

if (type == JUMP_LABEL_JMP) {
- if (init) {
- /*
- * Jump label is enabled for the first time.
- * So we expect a default_nop...
- */
- if (unlikely(memcmp((void *)entry->code, default_nop, 5)
- != 0))
- bug_at((void *)entry->code, __LINE__);
- } else {
- /*
- * ...otherwise expect an ideal_nop. Otherwise
- * something went horribly wrong.
- */
- if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)
- != 0))
- bug_at((void *)entry->code, __LINE__);
- }
+ __jump_label_enabling_check(entry, type, init);

code.jump = 0xe9;
code.offset = entry->target -
(entry->code + JUMP_LABEL_NOP_SIZE);
} else {
- /*
- * We are disabling this jump label. If it is not what
- * we think it is, then something must have gone wrong.
- * If this is the first initialization call, then we
- * are converting the default nop to the ideal nop.
- */
- if (init) {
- if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))
- bug_at((void *)entry->code, __LINE__);
- } else {
- code.jump = 0xe9;
- code.offset = entry->target -
- (entry->code + JUMP_LABEL_NOP_SIZE);
- if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))
- bug_at((void *)entry->code, __LINE__);
- }
+ __jump_label_disabling_check(entry, type, init);
memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
}

--
2.17.1
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