1 files changed, 49 insertions, 37 deletions

diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c
index b987ab2c1541..e808bb8bc0da 100644
--- a/arch/s390/kernel/jump_label.c
+++ b/arch/s390/kernel/jump_label.c
@@ -1,70 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Jump label s390 support
  *
  * Copyright IBM Corp. 2011
  * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
  */
-#include <linux/module.h>
 #include <linux/uaccess.h>
-#include <linux/stop_machine.h>
 #include <linux/jump_label.h>
+#include <linux/module.h>
+#include <asm/text-patching.h>
 #include <asm/ipl.h>
 
-#ifdef HAVE_JUMP_LABEL
-
 struct insn {
 	u16 opcode;
 	s32 offset;
 } __packed;
 
-struct insn_args {
-	struct jump_entry *entry;
-	enum jump_label_type type;
-};
+static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
+{
+	/* brcl 0,offset */
+	insn->opcode = 0xc004;
+	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
+}
 
-static void __jump_label_transform(struct jump_entry *entry,
-				   enum jump_label_type type)
+static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
 {
-	struct insn insn;
-	int rc;
+	/* brcl 15,offset */
+	insn->opcode = 0xc0f4;
+	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
+}
 
-	if (type == JUMP_LABEL_ENABLE) {
-		/* brcl 15,offset */
-		insn.opcode = 0xc0f4;
-		insn.offset = (entry->target - entry->code) >> 1;
-	} else {
-		/* brcl 0,0 */
-		insn.opcode = 0xc004;
-		insn.offset = 0;
-	}
+static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
+			   struct insn *new)
+{
+	unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
+	unsigned char *ipe = (unsigned char *)expected;
+	unsigned char *ipn = (unsigned char *)new;
 
-	rc = probe_kernel_write((void *)entry->code, &insn, JUMP_LABEL_NOP_SIZE);
-	WARN_ON_ONCE(rc < 0);
+	pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
+	pr_emerg("Found:    %6ph\n", ipc);
+	pr_emerg("Expected: %6ph\n", ipe);
+	pr_emerg("New:      %6ph\n", ipn);
+	panic("Corrupted kernel text");
 }
 
-static int __sm_arch_jump_label_transform(void *data)
+static void jump_label_transform(struct jump_entry *entry,
+				 enum jump_label_type type)
 {
-	struct insn_args *args = data;
+	void *code = (void *)jump_entry_code(entry);
+	struct insn old, new;
 
-	__jump_label_transform(args->entry, args->type);
-	return 0;
+	if (type == JUMP_LABEL_JMP) {
+		jump_label_make_nop(entry, &old);
+		jump_label_make_branch(entry, &new);
+	} else {
+		jump_label_make_branch(entry, &old);
+		jump_label_make_nop(entry, &new);
+	}
+	if (memcmp(code, &old, sizeof(old)))
+		jump_label_bug(entry, &old, &new);
+	s390_kernel_write(code, &new, sizeof(new));
 }
 
 void arch_jump_label_transform(struct jump_entry *entry,
 			       enum jump_label_type type)
 {
-	struct insn_args args;
-
-	args.entry = entry;
-	args.type = type;
-
-	stop_machine(__sm_arch_jump_label_transform, &args, NULL);
+	jump_label_transform(entry, type);
+	text_poke_sync();
 }
 
-void arch_jump_label_transform_static(struct jump_entry *entry,
-				      enum jump_label_type type)
+bool arch_jump_label_transform_queue(struct jump_entry *entry,
+				     enum jump_label_type type)
 {
-	__jump_label_transform(entry, type);
+	jump_label_transform(entry, type);
+	return true;
 }
 
-#endif
+void arch_jump_label_transform_apply(void)
+{
+	text_poke_sync();
+}