arm64: klib: Optimised atomic bitops

[~andy/linux] / arch / arm64 / lib / bitops.S

diff --git a/arch/arm64/lib/bitops.S b/arch/arm64/lib/bitops.S
new file mode 100644 (file)
index 0000000..fd1e801
--- /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