x86/jump_label: Add a __jump_label_set_jump_code() helper

Move the definition of the code to be written from
__jump_label_transform() to a specialized 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/d2f52a0010ecd399cf9b02a65bcf5836571b9e52.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index e631c358f7f4a69c58df1aa83663ee9e5b9569ac..f33408f1c3f6f6281390c6e0a34d458730baaac2 100644 (file)
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -35,41 +35,43 @@ static void bug_at(unsigned char *ip, int line)
        BUG();
 }
 
-static void __ref __jump_label_transform(struct jump_entry *entry,
-                                        enum jump_label_type type,
-                                        int init)
+static void __jump_label_set_jump_code(struct jump_entry *entry,
+                                      enum jump_label_type type,
+                                      union jump_code_union *code,
+                                      int init)
 {
-       union jump_code_union jmp;
        const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
        const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
-       const void *expect, *code;
+       const void *expect;
        int line;
 
-       jmp.jump = 0xe9;
-       jmp.offset = jump_entry_target(entry) -
-                    (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
-
-       if (type == JUMP_LABEL_JMP) {
-               if (init) {
-                       expect = default_nop; line = __LINE__;
-               } else {
-                       expect = ideal_nop; line = __LINE__;
-               }
+       code->jump = 0xe9;
+       code->offset = jump_entry_target(entry) -
+                      (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 
-               code = &jmp.code;
+       if (init) {
+               expect = default_nop; line = __LINE__;
+       } else if (type == JUMP_LABEL_JMP) {
+               expect = ideal_nop; line = __LINE__;
        } else {
-               if (init) {
-                       expect = default_nop; line = __LINE__;
-               } else {
-                       expect = &jmp.code; line = __LINE__;
-               }
-
-               code = ideal_nop;
+               expect = code->code; line = __LINE__;
        }
 
        if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
                bug_at((void *)jump_entry_code(entry), line);
 
+       if (type == JUMP_LABEL_NOP)
+               memcpy(code, ideal_nop, JUMP_LABEL_NOP_SIZE);
+}
+
+static void __ref __jump_label_transform(struct jump_entry *entry,
+                                        enum jump_label_type type,
+                                        int init)
+{
+       union jump_code_union code;
+
+       __jump_label_set_jump_code(entry, type, &code, init);
+
        /*
         * As long as only a single processor is running and the code is still
         * not marked as RO, text_poke_early() can be used; Checking that
@@ -82,12 +84,12 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
         * always nop being the 'currently valid' instruction
         */
        if (init || system_state == SYSTEM_BOOTING) {
-               text_poke_early((void *)jump_entry_code(entry), code,
+               text_poke_early((void *)jump_entry_code(entry), &code,
                                JUMP_LABEL_NOP_SIZE);
                return;
        }
 
-       text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,
+       text_poke_bp((void *)jump_entry_code(entry), &code, JUMP_LABEL_NOP_SIZE,
                     (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 }