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Diffstat (limited to 'arch/s390/kernel/jump_label.c')
-rw-r--r--arch/s390/kernel/jump_label.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c
new file mode 100644
index 000000000..a90299600
--- /dev/null
+++ b/arch/s390/kernel/jump_label.c
@@ -0,0 +1,109 @@
+/*
+ * 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 <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 0,0 */
+ insn->opcode = 0xc004;
+ insn->offset = 0;
+}
+
+static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
+{
+ /* brcl 15,offset */
+ insn->opcode = 0xc0f4;
+ insn->offset = (entry->target - entry->code) >> 1;
+}
+
+static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
+ struct insn *new)
+{
+ unsigned char *ipc = (unsigned char *)entry->code;
+ unsigned char *ipe = (unsigned char *)expected;
+ unsigned char *ipn = (unsigned char *)new;
+
+ pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
+ pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n",
+ ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]);
+ pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n",
+ ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]);
+ pr_emerg("New: %02x %02x %02x %02x %02x %02x\n",
+ ipn[0], ipn[1], ipn[2], ipn[3], ipn[4], ipn[5]);
+ panic("Corrupted kernel text");
+}
+
+static struct insn orignop = {
+ .opcode = 0xc004,
+ .offset = JUMP_LABEL_NOP_OFFSET >> 1,
+};
+
+static void __jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type,
+ int init)
+{
+ struct insn old, new;
+
+ if (type == JUMP_LABEL_ENABLE) {
+ 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 (init) {
+ if (memcmp((void *)entry->code, &orignop, sizeof(orignop)))
+ jump_label_bug(entry, &orignop, &new);
+ } else {
+ if (memcmp((void *)entry->code, &old, sizeof(old)))
+ jump_label_bug(entry, &old, &new);
+ }
+ s390_kernel_write((void *)entry->code, &new, sizeof(new));
+}
+
+static int __sm_arch_jump_label_transform(void *data)
+{
+ struct insn_args *args = data;
+
+ __jump_label_transform(args->entry, args->type, 0);
+ return 0;
+}
+
+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);
+}
+
+void arch_jump_label_transform_static(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ __jump_label_transform(entry, type, 1);
+}
+
+#endif