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Date: Wed, 16 Mar 2011 15:58:30 -0400
From: Jason Baron <jbaron@...hat.com>
To: rostedt@...dmis.org
Cc: peterz@...radead.org, hpa@...or.com, mathieu.desnoyers@...ymtl.ca,
mingo@...e.hu, tglx@...utronix.de, andi@...stfloor.org,
roland@...hat.com, rth@...hat.com, masami.hiramatsu.pt@...achi.com,
fweisbec@...il.com, avi@...hat.com, davem@...emloft.net,
sam@...nborg.org, ddaney@...iumnetworks.com,
michael@...erman.id.au, ralf@...ux-mips.org,
jang@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] jump label: add s390 support
From: Jan Glauber <jang@...ux.vnet.ibm.com>
Implement the architecture backend for jump label support on s390.
For a shared kernel booted from a NSS silently disable jump labels
because the NSS is read-only. Therefore jump labels will be disabled
in a shared kernel and can't be activated.
Signed-off-by: Jan Glauber <jang@...ux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
arch/s390/Kconfig | 1 +
arch/s390/include/asm/jump_label.h | 37 ++++++++++++++++++++++
arch/s390/kernel/Makefile | 2 +-
arch/s390/kernel/jump_label.c | 59 ++++++++++++++++++++++++++++++++++++
4 files changed, 98 insertions(+), 1 deletions(-)
create mode 100644 arch/s390/include/asm/jump_label.h
create mode 100644 arch/s390/kernel/jump_label.c
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 636bcb8..0739c8b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -87,6 +87,7 @@ config S390
select HAVE_KERNEL_LZO
select HAVE_GET_USER_PAGES_FAST
select HAVE_ARCH_MUTEX_CPU_RELAX
+ select HAVE_ARCH_JUMP_LABEL if !MARCH_G5
select ARCH_INLINE_SPIN_TRYLOCK
select ARCH_INLINE_SPIN_TRYLOCK_BH
select ARCH_INLINE_SPIN_LOCK
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
new file mode 100644
index 0000000..95a6cf2
--- /dev/null
+++ b/arch/s390/include/asm/jump_label.h
@@ -0,0 +1,37 @@
+#ifndef _ASM_S390_JUMP_LABEL_H
+#define _ASM_S390_JUMP_LABEL_H
+
+#include <linux/types.h>
+
+#define JUMP_LABEL_NOP_SIZE 6
+
+#ifdef CONFIG_64BIT
+#define ASM_PTR ".quad"
+#define ASM_ALIGN ".balign 8"
+#else
+#define ASM_PTR ".long"
+#define ASM_ALIGN ".balign 4"
+#endif
+
+static __always_inline bool arch_static_branch(struct jump_label_key *key)
+{
+ asm goto("0: brcl 0,0\n"
+ ".pushsection __jump_table, \"aw\"\n"
+ ASM_ALIGN "\n"
+ ASM_PTR " 0b, %l[label], %0\n"
+ ".popsection\n"
+ : : "X" (key) : : label);
+ return false;
+label:
+ return true;
+}
+
+typedef unsigned long jump_label_t;
+
+struct jump_entry {
+ jump_label_t code;
+ jump_label_t target;
+ jump_label_t key;
+};
+
+#endif
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 64230bc..5ff15da 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -23,7 +23,7 @@ CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
obj-y := bitmap.o traps.o time.o process.o base.o early.o setup.o \
processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
s390_ext.o debug.o irq.o ipl.o dis.o diag.o mem_detect.o \
- vdso.o vtime.o sysinfo.o nmi.o sclp.o
+ vdso.o vtime.o sysinfo.o nmi.o sclp.o jump_label.o
obj-y += $(if $(CONFIG_64BIT),entry64.o,entry.o)
obj-y += $(if $(CONFIG_64BIT),reipl64.o,reipl.o)
diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c
new file mode 100644
index 0000000..44cc06b
--- /dev/null
+++ b/arch/s390/kernel/jump_label.c
@@ -0,0 +1,59 @@
+/*
+ * Jump label s390 support
+ *
+ * Copyright IBM Corp. 2011
+ * Author(s): Jan Glauber <jang@...ux.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 {
+ unsigned long *target;
+ struct insn *insn;
+ ssize_t size;
+};
+
+static int __arch_jump_label_transform(void *data)
+{
+ struct insn_args *args = data;
+ int rc;
+
+ rc = probe_kernel_write(args->target, args->insn, args->size);
+ WARN_ON_ONCE(rc < 0);
+ return 0;
+}
+
+void arch_jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ struct insn_args args;
+ struct insn insn;
+
+ 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;
+ }
+
+ args.target = (void *) entry->code;
+ args.insn = &insn;
+ args.size = JUMP_LABEL_NOP_SIZE;
+
+ stop_machine(__arch_jump_label_transform, &args, NULL);
+}
+
+#endif
--
1.7.1
--
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