[PATCH] jump label: Add MIPS support.

David Daney
2010-09-28T18:10:41Z

When in Rome...

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>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
---
arch/mips/Kconfig | 1 +
arch/mips/include/asm/jump_label.h | 48 ++++++++++++++++++++++++++++
arch/mips/kernel/Makefile | 3 +-
arch/mips/kernel/jump_label.c | 60 ++++++++++++++++++++++++++++++++++++
arch/mips/kernel/module.c | 5 +++
5 files changed, 116 insertions(+), 1 deletions(-)
create mode 100644 arch/mips/include/asm/jump_label.h
create mode 100644 arch/mips/kernel/jump_label.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3ad59dd..6b3bdb5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -13,6 +13,7 @@ config MIPS
select HAVE_KPROBES
select HAVE_KRETPROBES
select RTC_LIB if !MACH_LOONGSON
+ select HAVE_ARCH_JUMP_LABEL

mainmenu "Linux/MIPS Kernel Configuration"

diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
new file mode 100644
index 0000000..7622ccf
--- /dev/null
+++ b/arch/mips/include/asm/jump_label.h
@@ -0,0 +1,48 @@
+/*
+ * 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.
+ */
+#ifndef _ASM_MIPS_JUMP_LABEL_H
+#define _ASM_MIPS_JUMP_LABEL_H
+
+#include <linux/types.h>
+
+#ifdef __KERNEL__
+
+#define JUMP_LABEL_NOP_SIZE 4
+
+#ifdef CONFIG_64BIT
+#define WORD_INSN ".dword"
+#else
+#define WORD_INSN ".word"
+#endif
+
+#define JUMP_LABEL(key, label) \
+ do { \
+ asm goto("1:\tnop\n\t" \
+ "nop\n\t" \
+ ".pushsection __jump_table, \"a\"\n\t" \
+ WORD_INSN " 1b, %l[" #label "], %0\n\t" \
+ ".popsection\n\t" \
+ : : "i" (key) : : label); \
+ } while (0)
+
+
+#endif /* __KERNEL__ */
+
+#ifdef CONFIG_64BIT
+typedef u64 jump_label_t;
+#else
+typedef u32 jump_label_t;
+#endif
+
+struct jump_entry {
+ jump_label_t code;
+ jump_label_t target;
+ jump_label_t key;
+};
+
+#endif /* _ASM_MIPS_JUMP_LABEL_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 06f8482..db4feb9 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -6,7 +6,8 @@ extra-y := head.o init_task.o vmlinux.lds

obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \
ptrace.o reset.o setup.o signal.o syscall.o \
- time.o topology.o traps.o unaligned.o watch.o vdso.o
+ time.o topology.o traps.o unaligned.o watch.o vdso.o \
+ jump_label.o

ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_ftrace.o = -pg
diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c
new file mode 100644
index 0000000..3c145a8
--- /dev/null
+++ b/arch/mips/kernel/jump_label.c
@@ -0,0 +1,60 @@
+/*
+ * 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>
+
+#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();
+}
+
+void arch_jump_label_text_poke_early(jump_label_t addr)
+{
+ union mips_instruction *insn_p =
+ (union mips_instruction *)(unsigned long)addr;
+
+ insn_p->word = 0; /* nop */
+ flush_icache_range((unsigned long)insn_p,
+ (unsigned long)insn_p + sizeof(*insn_p));
+}
diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index 6f51dda..bb9cde4 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -30,6 +30,8 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
+#include <linux/jump_label.h>
+
#include <asm/pgtable.h> /* MODULE_START */

struct mips_hi16 {
@@ -390,6 +392,9 @@ int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *s;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

+ /* Make jump label nops. */
+ jump_label_apply_nops(me);
+
INIT_LIST_HEAD(&me->arch.dbe_list);
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
--
1.7.2.2