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Date: Wed, 22 Feb 2017 04:11:40 +0900
From: Stafford Horne <shorne@...il.com>
To: Jonas Bonn <jonas@...thpole.se>,
Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Cc: linux@...ck-us.net, openrisc@...ts.librecores.org,
linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Stafford Horne <shorne@...il.com>
Subject: [PATCH v3 11/25] openrisc: add futex_atomic_* implementations
From: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Support for the futex_atomic_* operations by using the
load-link/store-conditional l.lwa/l.swa instructions.
Most openrisc cores provide these instructions now if not available,
emulation is provided.
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
[shorne@...il.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by
Alan Cox https://lkml.org/lkml/2014/7/23/666]
Signed-off-by: Stafford Horne <shorne@...il.com>
---
arch/openrisc/include/asm/Kbuild | 1 -
arch/openrisc/include/asm/futex.h | 135 ++++++++++++++++++++++++++++++++++++++
2 files changed, 135 insertions(+), 1 deletion(-)
create mode 100644 arch/openrisc/include/asm/futex.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index 1cedd63..a669c14 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -20,7 +20,6 @@ generic-y += exec.h
generic-y += fb.h
generic-y += fcntl.h
generic-y += ftrace.h
-generic-y += futex.h
generic-y += hardirq.h
generic-y += hw_irq.h
generic-y += ioctl.h
diff --git a/arch/openrisc/include/asm/futex.h b/arch/openrisc/include/asm/futex.h
new file mode 100644
index 0000000..7780873
--- /dev/null
+++ b/arch/openrisc/include/asm/futex.h
@@ -0,0 +1,135 @@
+#ifndef __ASM_OPENRISC_FUTEX_H
+#define __ASM_OPENRISC_FUTEX_H
+
+#ifdef __KERNEL__
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+({ \
+ __asm__ __volatile__ ( \
+ "1: l.lwa %0, %2 \n" \
+ insn "\n" \
+ "2: l.swa %2, %1 \n" \
+ " l.bnf 1b \n" \
+ " l.ori %1, r0, 0 \n" \
+ "3: \n" \
+ ".section .fixup,\"ax\" \n" \
+ "4: l.j 3b \n" \
+ " l.addi %1, r0, %3 \n" \
+ ".previous \n" \
+ ".section __ex_table,\"a\" \n" \
+ ".word 1b,4b,2b,4b \n" \
+ ".previous \n" \
+ : "=&r" (oldval), "=&r" (ret), "+m" (*uaddr) \
+ : "i" (-EFAULT), "r" (oparg) \
+ : "cc", "memory" \
+ ); \
+})
+
+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;
+
+ if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+ oparg = 1 << oparg;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ pagefault_disable();
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("l.or %1,%4,%4", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("l.add %1,%0,%4", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("l.or %1,%0,%4", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("l.and %1,%0,%4", ret, oldval, uaddr, ~oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("l.xor %1,%0,%4", ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_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 prev;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ __asm__ __volatile__ ( \
+ "1: l.lwa %1, %2 \n" \
+ " l.sfeq %1, %3 \n" \
+ " l.bnf 3f \n" \
+ " l.nop \n" \
+ "2: l.swa %2, %4 \n" \
+ " l.bnf 1b \n" \
+ " l.nop \n" \
+ "3: \n" \
+ ".section .fixup,\"ax\" \n" \
+ "4: l.j 3b \n" \
+ " l.addi %0, r0, %5 \n" \
+ ".previous \n" \
+ ".section __ex_table,\"a\" \n" \
+ ".word 1b,4b,2b,4b \n" \
+ ".previous \n" \
+ : "+r" (ret), "=&r" (prev), "+m" (*uaddr) \
+ : "r" (oldval), "r" (newval), "i" (-EFAULT) \
+ : "cc", "memory" \
+ );
+
+ *uval = prev;
+ return ret;
+}
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASM_OPENRISC_FUTEX_H */
--
2.9.3
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