Re: alpha: half done futex implementation

[Matt Turner <mattst88@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 521 bytes --]

Hi,

Attached is a patch to (almost) add native futex support to Alpha.

It doesn't compile...

  CC      kernel/futex.o
kernel/futex.c: In function 'do_futex':
/usr/src/linux-radeon/glisse-drm/arch/alpha/include/asm/futex.h:47:
error: invalid 'asm': operand number out of range
{standard input}: Assembler messages:
{standard input}:3722: Error: bad expression
{standard input}:3722: Error: syntax error

I can't make much sense out of that.

I changed the %4's to %3 as we don't have a %4.

Please review.

Matt Turner

[-- Attachment #2: add-native-futex-support-on-alpha.patch --]
[-- Type: application/octet-stream, Size: 3141 bytes --]

diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h
index 6a332a9..45b54fa 100644
--- a/arch/alpha/include/asm/futex.h
+++ b/arch/alpha/include/asm/futex.h
@@ -1,6 +1,115 @@
-#ifndef _ASM_FUTEX_H
-#define _ASM_FUTEX_H
+#ifndef _ASM_ALPHA_FUTEX_H
+#define _ASM_ALPHA_FUTEX_H
 
-#include <asm-generic/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:	ldl_l	%0,0(%3)\n"			\
+	insn							\
+	"2:	stl_c	%1,0(%3)\n"			\
+	"	beq		%1,4f\n"			\
+	"	mov		$31,%1\n"			\
+	"3:	.subsection 2\n"			\
+	"4:	br		1b\n"				\
+	"	.previous\n"				\
+	"	.section __ex_table,\"a\"\n"\
+	"	.long	1b-.\n"				\
+	"	lda		%0,3b-1b(%2)\n"		\
+		".long	2b-.\n"				\
+	"	lda		%0,3b-2b(%2)\n"		\
+	"	.previous\n"				\
+	:	"=&r" (oldval), "=&r"(ret)	\
+	:	"r" (uaddr), "r"(oparg)		\
+	:	"memory")
+
+static inline int futex_atomic_op_inuser (int encoded_op, int __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(int)))
+		return -EFAULT;
+
+	pagefault_disable();
+
+	switch (op) {
+	case FUTEX_OP_SET:
+		__futex_atomic_op("mov %3,%1", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ADD:
+		__futex_atomic_op("addl %0,%3,%1\n", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_OR:
+		__futex_atomic_op("or %0,%3,%1\n", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ANDN:
+		__futex_atomic_op("andnot %0,%3,%1\n", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_XOR:
+		__futex_atomic_op("xor %0,%3,%1\n", 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(int __user *uaddr, int oldval, int newval)
+{
+	int prev;
+
+	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+		return -EFAULT;
+
+	__asm__ __volatile__ (
+#ifdef CONFIG_SMP
+	"	mb\n"
 #endif
+	"1:	ldl_l	%0,0(%3)        # futex_atomic_cmpxchg_inatomic\n"
+	"	cmpeq	%0,%3,%0\n"
+	"	beq		%0,3f\n"
+	"2:	stl_c	%4,0(%2)\n"
+	"	beq		%4,1b\n"
+	"3:	.subsection 2\n"
+	"4:	br		1b\n"
+	"	.previous\n"
+	"	.section __ex_table,\"a\"\n"
+	"	.long	1b-.\n"
+	"	lda		%0,3b-1b(%2)\n"
+		".long	2b-.\n"
+	"	lda		%0,3b-2b(%2)\n"
+	"	.previous\n"
+	: "=&r" (prev), "+m" (*uaddr)
+	: "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)
+	: "memory");
+
+	return prev;
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_ALPHA_FUTEX_H */