MIPS: jump label: Add MIPS support.

In order not to be left behind, we add jump label support for MIPS.

Tested on 64-bit big endian (Octeon), and 32-bit little endian
(malta/qemu).

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
Patchwork: https://patchwork.linux-mips.org/patch/1923/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c
new file mode 100644
index 000000000000..6001610cfe55
--- /dev/null
+++ b/arch/mips/kernel/jump_label.c
@@ -0,0 +1,54 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2010 Cavium Networks, Inc.
+ */
+
+#include <linux/jump_label.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/cpu.h>
+
+#include <asm/cacheflush.h>
+#include <asm/inst.h>
+
+#ifdef HAVE_JUMP_LABEL
+
+#define J_RANGE_MASK ((1ul << 28) - 1)
+
+void arch_jump_label_transform(struct jump_entry *e,
+                               enum jump_label_type type)
+{
+        union mips_instruction insn;
+        union mips_instruction *insn_p =
+                (union mips_instruction *)(unsigned long)e->code;
+
+        /* Jump only works within a 256MB aligned region. */
+        BUG_ON((e->target & ~J_RANGE_MASK) != (e->code & ~J_RANGE_MASK));
+
+        /* Target must have 4 byte alignment. */
+        BUG_ON((e->target & 3) != 0);
+
+        if (type == JUMP_LABEL_ENABLE) {
+                insn.j_format.opcode = j_op;
+                insn.j_format.target = (e->target & J_RANGE_MASK) >> 2;
+        } else {
+                insn.word = 0; /* nop */
+        }
+
+        get_online_cpus();
+        mutex_lock(&text_mutex);
+        *insn_p = insn;
+
+        flush_icache_range((unsigned long)insn_p,
+                           (unsigned long)insn_p + sizeof(*insn_p));
+
+        mutex_unlock(&text_mutex);
+        put_online_cpus();
+}
+
+#endif /* HAVE_JUMP_LABEL */