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Diffstat (limited to 'arch/arc/include/asm/futex.h')
-rw-r--r--arch/arc/include/asm/futex.h152
1 files changed, 85 insertions, 67 deletions
diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
index 4dc64ddebece..607d1c16d4dd 100644
--- a/arch/arc/include/asm/futex.h
+++ b/arch/arc/include/asm/futex.h
@@ -1,10 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
- * 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.
- *
* Vineetg: August 2010: From Android kernel work
*/
@@ -16,18 +13,22 @@
#include <linux/uaccess.h>
#include <asm/errno.h>
+#ifdef CONFIG_ARC_HAS_LLSC
+
#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
\
+ smp_mb(); \
__asm__ __volatile__( \
- "1: ld %1, [%2] \n" \
+ "1: llock %1, [%2] \n" \
insn "\n" \
- "2: st %0, [%2] \n" \
+ "2: scond %0, [%2] \n" \
+ " bnz 1b \n" \
" mov %0, 0 \n" \
"3: \n" \
" .section .fixup,\"ax\" \n" \
" .align 4 \n" \
"4: mov %0, %4 \n" \
- " b 3b \n" \
+ " j 3b \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" .align 4 \n" \
@@ -37,29 +38,56 @@
\
: "=&r" (ret), "=&r" (oldval) \
: "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
- : "cc", "memory")
+ : "cc", "memory"); \
+ smp_mb() \
+
+#else /* !CONFIG_ARC_HAS_LLSC */
-static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
+ \
+ smp_mb(); \
+ __asm__ __volatile__( \
+ "1: ld %1, [%2] \n" \
+ insn "\n" \
+ "2: st %0, [%2] \n" \
+ " mov %0, 0 \n" \
+ "3: \n" \
+ " .section .fixup,\"ax\" \n" \
+ " .align 4 \n" \
+ "4: mov %0, %4 \n" \
+ " j 3b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " .align 4 \n" \
+ " .word 1b, 4b \n" \
+ " .word 2b, 4b \n" \
+ " .previous \n" \
+ \
+ : "=&r" (ret), "=&r" (oldval) \
+ : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
+ : "cc", "memory"); \
+ smp_mb() \
+
+#endif
+
+static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+ 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(int)))
+ if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
- pagefault_disable(); /* implies preempt_disable() */
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_disable(); /* to guarantee atomic r-m-w of futex op */
+#endif
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
+ /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
__futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
@@ -75,77 +103,67 @@ static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
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;
- }
- }
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_enable();
+#endif
+
+ if (!ret)
+ *oval = oldval;
+
return ret;
}
-/* Compare-xchg with preemption disabled.
- * Notes:
- * -Best-Effort: Exchg happens only if compare succeeds.
- * If compare fails, returns; leaving retry/looping to upper layers
- * -successful cmp-xchg: return orig value in @addr (same as cmp val)
- * -Compare fails: return orig value in @addr
- * -user access r/w fails: return -EFAULT
+/*
+ * cmpxchg of futex (pagefaults disabled by caller)
+ * Return 0 for success, -EFAULT otherwise
*/
static inline int
-futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
- u32 newval)
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
+ u32 newval)
{
- u32 val;
+ int ret = 0;
+ u32 existval;
- if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
- pagefault_disable(); /* implies preempt_disable() */
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_disable(); /* to guarantee atomic r-m-w of futex op */
+#endif
+ smp_mb();
- /* TBD : can use llock/scond */
__asm__ __volatile__(
- "1: ld %0, [%3] \n"
- " brne %0, %1, 3f \n"
- "2: st %2, [%3] \n"
+#ifdef CONFIG_ARC_HAS_LLSC
+ "1: llock %1, [%4] \n"
+ " brne %1, %2, 3f \n"
+ "2: scond %3, [%4] \n"
+ " bnz 1b \n"
+#else
+ "1: ld %1, [%4] \n"
+ " brne %1, %2, 3f \n"
+ "2: st %3, [%4] \n"
+#endif
"3: \n"
" .section .fixup,\"ax\" \n"
- "4: mov %0, %4 \n"
- " b 3b \n"
+ "4: mov %0, %5 \n"
+ " j 3b \n"
" .previous \n"
" .section __ex_table,\"a\" \n"
" .align 4 \n"
" .word 1b, 4b \n"
" .word 2b, 4b \n"
" .previous\n"
- : "=&r"(val)
- : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
+ : "+&r"(ret), "=&r"(existval)
+ : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
: "cc", "memory");
- pagefault_enable(); /* subsumes preempt_enable() */
+ smp_mb();
- *uval = val;
- return val;
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_enable();
+#endif
+ *uval = existval;
+ return ret;
}
#endif
generated by cgit (git 2.34.1) at 2025-12-25 06:59:09 +0000