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authorCatalin Marinas <catalin.marinas@arm.com>2012-03-05 11:49:29 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2012-09-17 13:42:02 +0100
commit6170a97460dbda12686bef0dec65ce2d59867f9e (patch)
tree8e4fde78c58d30e2fc3af4be6b0fff0371c5f79f /arch/arm64/include/asm/futex.h
parentarm64: IRQ handling (diff)
downloadlinux-dev-6170a97460dbda12686bef0dec65ce2d59867f9e.tar.xz
linux-dev-6170a97460dbda12686bef0dec65ce2d59867f9e.zip
arm64: Atomic operations
This patch introduces the atomic, mutex and futex operations. Many atomic operations use the load-acquire and store-release operations which imply barriers, avoiding the need for explicit DMB. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to '')
-rw-r--r--arch/arm64/include/asm/futex.h136
1 files changed, 136 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
new file mode 100644
index 000000000000..3468ae8439fa
--- /dev/null
+++ b/arch/arm64/include/asm/futex.h
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_FUTEX_H
+#define __ASM_FUTEX_H
+
+#ifdef __KERNEL__
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
+ asm volatile( \
+"1: ldaxr %w1, %2\n" \
+ insn "\n" \
+"2: stlxr %w3, %w0, %2\n" \
+" cbnz %w3, 1b\n" \
+"3:\n" \
+" .pushsection .fixup,\"ax\"\n" \
+"4: mov %w0, %w5\n" \
+" b 3b\n" \
+" .popsection\n" \
+" .pushsection __ex_table,\"a\"\n" \
+" .align 3\n" \
+" .quad 1b, 4b, 2b, 4b\n" \
+" .popsection\n" \
+ : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \
+ : "r" (oparg), "Ir" (-EFAULT) \
+ : "cc")
+
+static inline int
+futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
+{
+ int op = (encoded_op >> 28) & 7;
+ int cmp = (encoded_op >> 24) & 15;
+ int oparg = (encoded_op << 8) >> 20;
+ int cmparg = (encoded_op << 20) >> 20;
+ int oldval = 0, ret, tmp;
+
+ if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+ oparg = 1 << oparg;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ pagefault_disable(); /* implies preempt_disable() */
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("mov %w0, %w4",
+ ret, oldval, uaddr, tmp, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("add %w0, %w1, %w4",
+ ret, oldval, uaddr, tmp, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("orr %w0, %w1, %w4",
+ ret, oldval, uaddr, tmp, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("and %w0, %w1, %w4",
+ ret, oldval, uaddr, tmp, ~oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("eor %w0, %w1, %w4",
+ ret, oldval, uaddr, tmp, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_enable(); /* subsumes preempt_enable() */
+
+ if (!ret) {
+ switch (cmp) {
+ case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
+ case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
+ case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
+ case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
+ case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
+ case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
+ default: ret = -ENOSYS;
+ }
+ }
+ return ret;
+}
+
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
+ u32 oldval, u32 newval)
+{
+ int ret = 0;
+ u32 val, tmp;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ asm volatile("// futex_atomic_cmpxchg_inatomic\n"
+"1: ldaxr %w1, %2\n"
+" sub %w3, %w1, %w4\n"
+" cbnz %w3, 3f\n"
+"2: stlxr %w3, %w5, %2\n"
+" cbnz %w3, 1b\n"
+"3:\n"
+" .pushsection .fixup,\"ax\"\n"
+"4: mov %w0, %w6\n"
+" b 3b\n"
+" .popsection\n"
+" .pushsection __ex_table,\"a\"\n"
+" .align 3\n"
+" .quad 1b, 4b, 2b, 4b\n"
+" .popsection\n"
+ : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
+ : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
+ : "cc", "memory");
+
+ *uval = val;
+ return ret;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_FUTEX_H */