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authorMichael Ellerman <michael@ellerman.id.au>2011-06-29 19:16:59 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-07-01 13:48:55 +1000
commitac5f89c7d87f6f2fb7073723fc943488d9c3479d (patch)
treef7373ad0d4af2c937a420f3909284814d4487535
parent87fa35dd881fd61a2a8166892366f2c22c34a1fa (diff)
downloadlinux-ac5f89c7d87f6f2fb7073723fc943488d9c3479d.tar.gz
powerpc: Add jump label support
This patch adds support for the new "jump label" feature. Unlike x86 and sparc we just merrily patch the code with no locks etc, as far as I know this is safe, but I'm not really sure what the x86/sparc code is protecting against so maybe it's not. I also don't see any reason for us to implement the poke_early() routine, even though sparc does. [BenH: Updated the patch to upstream generic changes] Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/Kconfig1
-rw-r--r--arch/powerpc/include/asm/jump_label.h47
-rw-r--r--arch/powerpc/kernel/Makefile1
-rw-r--r--arch/powerpc/kernel/jump_label.c23
4 files changed, 72 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2729c6663d8a..c15f2e61e4fd 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -134,6 +134,7 @@ config PPC
select GENERIC_IRQ_SHOW_LEVEL
select HAVE_RCU_TABLE_FREE if SMP
select HAVE_SYSCALL_TRACEPOINTS
+ select HAVE_ARCH_JUMP_LABEL
config EARLY_PRINTK
bool
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
new file mode 100644
index 000000000000..1f780b95c0f0
--- /dev/null
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -0,0 +1,47 @@
+#ifndef _ASM_POWERPC_JUMP_LABEL_H
+#define _ASM_POWERPC_JUMP_LABEL_H
+
+/*
+ * Copyright 2010 Michael Ellerman, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/types.h>
+
+#include <asm/feature-fixups.h>
+
+#define JUMP_ENTRY_TYPE stringify_in_c(FTR_ENTRY_LONG)
+#define JUMP_LABEL_NOP_SIZE 4
+
+static __always_inline bool arch_static_branch(struct jump_label_key *key)
+{
+ asm goto("1:\n\t"
+ "nop\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".align 4\n\t"
+ JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
+ ".popsection \n\t"
+ : : "i" (key) : : l_yes);
+ return false;
+l_yes:
+ return true;
+}
+
+#ifdef CONFIG_PPC64
+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;
+ jump_label_t pad;
+};
+
+#endif /* _ASM_POWERPC_JUMP_LABEL_H */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e8b981897d44..ce4f7f179117 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_MODULES) += module.o module_$(CONFIG_WORD_SIZE).o
obj-$(CONFIG_44x) += cpu_setup_44x.o
obj-$(CONFIG_PPC_FSL_BOOK3E) += cpu_setup_fsl_booke.o dbell.o
obj-$(CONFIG_PPC_BOOK3E_64) += dbell.o
+obj-$(CONFIG_JUMP_LABEL) += jump_label.o
extra-y := head_$(CONFIG_WORD_SIZE).o
extra-$(CONFIG_40x) := head_40x.o
diff --git a/arch/powerpc/kernel/jump_label.c b/arch/powerpc/kernel/jump_label.c
new file mode 100644
index 000000000000..368d158d665d
--- /dev/null
+++ b/arch/powerpc/kernel/jump_label.c
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010 Michael Ellerman, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/jump_label.h>
+#include <asm/code-patching.h>
+
+void arch_jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ u32 *addr = (u32 *)(unsigned long)entry->code;
+
+ if (type == JUMP_LABEL_ENABLE)
+ patch_branch(addr, entry->target, 0);
+ else
+ patch_instruction(addr, PPC_INST_NOP);
+}