x86/jump_label: Switch to jump_entry accessors

In preparation of switching x86 to use place-relative references for
the code, target and key members of struct jump_entry, replace direct
references to the struct members with invocations of the new accessors.
This will allow us to make the switch by modifying the accessors only.

This incorporates a cleanup of __jump_label_transform() proposed by
Peter.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-6-ard.biesheuvel@linaro.org

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index eeea935e9bb53ff9f6cfb0b75778e71c4889af84..aac0c1f7e3545c50b5229eb7652b68442ed82995 100644 (file)
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -42,55 +42,40 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
                                         void *(*poker)(void *, const void *, size_t),
                                         int init)
 {
-       union jump_code_union code;
+       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;
+       int line;
+
+       jmp.jump = 0xe9;
+       jmp.offset = jump_entry_target(entry) -
+                    (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 
        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__);
+                       expect = default_nop; line = __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__);
+                       expect = ideal_nop; line = __LINE__;
                }
 
-               code.jump = 0xe9;
-               code.offset = entry->target -
-                               (entry->code + JUMP_LABEL_NOP_SIZE);
+               code = &jmp.code;
        } 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__);
+                       expect = default_nop; line = __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__);
+                       expect = &jmp.code; line = __LINE__;
                }
-               memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
+
+               code = ideal_nop;
        }
 
+       if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
+               bug_at((void *)jump_entry_code(entry), line);
+
        /*
         * Make text_poke_bp() a default fallback poker.
         *
@@ -99,11 +84,14 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
         * always nop being the 'currently valid' instruction
         *
         */
-       if (poker)
-               (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
-       else
-               text_poke_bp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE,
-                            (void *)entry->code + JUMP_LABEL_NOP_SIZE);
+       if (poker) {
+               (*poker)((void *)jump_entry_code(entry), code,
+                        JUMP_LABEL_NOP_SIZE);
+               return;
+       }
+
+       text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,
+                    (void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 }
 
 void arch_jump_label_transform(struct jump_entry *entry,