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authorCatalin Marinas <catalin.marinas@arm.com>2013-03-21 16:28:47 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2013-03-21 17:39:31 +0000
commit62479586532715b6da4777374a6f53b32453385e (patch)
tree232004eb56bf36b966ea11ec8295a1b2893ac9e9 /arch/arm64
parentarm64: klib: Optimised string functions (diff)
downloadlinux-dev-62479586532715b6da4777374a6f53b32453385e.tar.xz
linux-dev-62479586532715b6da4777374a6f53b32453385e.zip
arm64: klib: Optimised atomic bitops
This patch implements the AArch64-specific atomic bitops functions using exclusive memory accesses to avoid locking. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/include/asm/bitops.h18
-rw-r--r--arch/arm64/kernel/arm64ksyms.c13
-rw-r--r--arch/arm64/lib/bitops.S70
-rw-r--r--arch/arm64/lib/bitops.c25
4 files changed, 94 insertions, 32 deletions
diff --git a/arch/arm64/include/asm/bitops.h b/arch/arm64/include/asm/bitops.h
index 5e693073b030..aa5b59d6ba43 100644
--- a/arch/arm64/include/asm/bitops.h
+++ b/arch/arm64/include/asm/bitops.h
@@ -32,6 +32,16 @@
#error only <linux/bitops.h> can be included directly
#endif
+/*
+ * Little endian assembly atomic bitops.
+ */
+extern void set_bit(int nr, volatile unsigned long *p);
+extern void clear_bit(int nr, volatile unsigned long *p);
+extern void change_bit(int nr, volatile unsigned long *p);
+extern int test_and_set_bit(int nr, volatile unsigned long *p);
+extern int test_and_clear_bit(int nr, volatile unsigned long *p);
+extern int test_and_change_bit(int nr, volatile unsigned long *p);
+
#include <asm-generic/bitops/builtin-__ffs.h>
#include <asm-generic/bitops/builtin-ffs.h>
#include <asm-generic/bitops/builtin-__fls.h>
@@ -45,9 +55,13 @@
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/lock.h>
-#include <asm-generic/bitops/atomic.h>
#include <asm-generic/bitops/non-atomic.h>
#include <asm-generic/bitops/le.h>
-#include <asm-generic/bitops/ext2-atomic.h>
+
+/*
+ * Ext2 is defined to use little-endian byte ordering.
+ */
+#define ext2_set_bit_atomic(lock, nr, p) test_and_set_bit_le(nr, p)
+#define ext2_clear_bit_atomic(lock, nr, p) test_and_clear_bit_le(nr, p)
#endif /* __ASM_BITOPS_H */
diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index a5d0d4643109..7df1aad29b67 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -39,11 +39,6 @@ EXPORT_SYMBOL(__copy_from_user);
EXPORT_SYMBOL(__copy_to_user);
EXPORT_SYMBOL(__clear_user);
- /* bitops */
-#ifdef CONFIG_SMP
-EXPORT_SYMBOL(__atomic_hash);
-#endif
-
/* physical memory */
EXPORT_SYMBOL(memstart_addr);
@@ -54,3 +49,11 @@ EXPORT_SYMBOL(memset);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memchr);
+
+ /* atomic bitops */
+EXPORT_SYMBOL(set_bit);
+EXPORT_SYMBOL(test_and_set_bit);
+EXPORT_SYMBOL(clear_bit);
+EXPORT_SYMBOL(test_and_clear_bit);
+EXPORT_SYMBOL(change_bit);
+EXPORT_SYMBOL(test_and_change_bit);
diff --git a/arch/arm64/lib/bitops.S b/arch/arm64/lib/bitops.S
new file mode 100644
index 000000000000..fd1e801b53e7
--- /dev/null
+++ b/arch/arm64/lib/bitops.S
@@ -0,0 +1,70 @@
+/*
+ * Based on arch/arm/lib/bitops.h
+ *
+ * Copyright (C) 2013 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/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * x0: bits 5:0 bit offset
+ * bits 63:6 word offset
+ * x1: address
+ */
+ .macro bitop, name, instr
+ENTRY( \name )
+ and x3, x0, #63 // Get bit offset
+ eor x0, x0, x3 // Clear low bits
+ mov x2, #1
+ add x1, x1, x0, lsr #3 // Get word offset
+ lsl x3, x2, x3 // Create mask
+1: ldxr x2, [x1]
+ \instr x2, x2, x3
+ stxr w0, x2, [x1]
+ cbnz w0, 1b
+ ret
+ENDPROC(\name )
+ .endm
+
+ .macro testop, name, instr
+ENTRY( \name )
+ and x3, x0, #63 // Get bit offset
+ eor x0, x0, x3 // Clear low bits
+ mov x2, #1
+ add x1, x1, x0, lsr #3 // Get word offset
+ lsl x4, x2, x3 // Create mask
+ smp_dmb ish
+1: ldxr x2, [x1]
+ lsr x0, x2, x3 // Save old value of bit
+ \instr x2, x2, x4 // toggle bit
+ stxr w2, x2, [x1]
+ cbnz w2, 1b
+ smp_dmb ish
+ and x0, x0, #1
+3: ret
+ENDPROC(\name )
+ .endm
+
+/*
+ * Atomic bit operations.
+ */
+ bitop change_bit, eor
+ bitop clear_bit, bic
+ bitop set_bit, orr
+
+ testop test_and_change_bit, eor
+ testop test_and_clear_bit, bic
+ testop test_and_set_bit, orr
diff --git a/arch/arm64/lib/bitops.c b/arch/arm64/lib/bitops.c
deleted file mode 100644
index aa4965e60acc..000000000000
--- a/arch/arm64/lib/bitops.c
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2012 ARM Limited
- *
- * 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/>.
- */
-
-#include <linux/kernel.h>
-#include <linux/spinlock.h>
-#include <linux/atomic.h>
-
-#ifdef CONFIG_SMP
-arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = {
- [0 ... (ATOMIC_HASH_SIZE-1)] = __ARCH_SPIN_LOCK_UNLOCKED
-};
-#endif