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authorIngo Molnar <mingo@kernel.org>2012-04-14 13:18:27 +0200
committerIngo Molnar <mingo@kernel.org>2012-04-14 13:19:04 +0200
commit6ac1ef482d7ae0c690f1640bf6eb818ff9a2d91e (patch)
tree021cc9f6b477146fcebe6f3be4752abfa2ba18a9 /arch/hexagon/include/asm/cmpxchg.h
parent682968e0c425c60f0dde37977e5beb2b12ddc4cc (diff)
parenta385ec4f11bdcf81af094c03e2444ee9b7fad2e5 (diff)
Merge branch 'perf/core' into perf/uprobes
Merge in latest upstream (and the latest perf development tree), to prepare for tooling changes, and also to pick up v3.4 MM changes that the uprobes code needs to take care of. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/hexagon/include/asm/cmpxchg.h')
-rw-r--r--arch/hexagon/include/asm/cmpxchg.h90
1 files changed, 90 insertions, 0 deletions
diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
new file mode 100644
index 000000000000..c5f9527e1df6
--- /dev/null
+++ b/arch/hexagon/include/asm/cmpxchg.h
@@ -0,0 +1,90 @@
+/*
+ * xchg/cmpxchg operations for the Hexagon architecture
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef _ASM_CMPXCHG_H
+#define _ASM_CMPXCHG_H
+
+/*
+ * __xchg - atomically exchange a register and a memory location
+ * @x: value to swap
+ * @ptr: pointer to memory
+ * @size: size of the value
+ *
+ * Only 4 bytes supported currently.
+ *
+ * Note: there was an errata for V2 about .new's and memw_locked.
+ *
+ */
+static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
+ int size)
+{
+ unsigned long retval;
+
+ /* Can't seem to use printk or panic here, so just stop */
+ if (size != 4) do { asm volatile("brkpt;\n"); } while (1);
+
+ __asm__ __volatile__ (
+ "1: %0 = memw_locked(%1);\n" /* load into retval */
+ " memw_locked(%1,P0) = %2;\n" /* store into memory */
+ " if !P0 jump 1b;\n"
+ : "=&r" (retval)
+ : "r" (ptr), "r" (x)
+ : "memory", "p0"
+ );
+ return retval;
+}
+
+/*
+ * Atomically swap the contents of a register with memory. Should be atomic
+ * between multiple CPU's and within interrupts on the same CPU.
+ */
+#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), \
+ sizeof(*(ptr))))
+
+/*
+ * see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps.
+ * looks just like atomic_cmpxchg on our arch currently with a bunch of
+ * variable casting.
+ */
+#define __HAVE_ARCH_CMPXCHG 1
+
+#define cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(ptr) __ptr = (ptr); \
+ __typeof__(*(ptr)) __old = (old); \
+ __typeof__(*(ptr)) __new = (new); \
+ __typeof__(*(ptr)) __oldval = 0; \
+ \
+ asm volatile( \
+ "1: %0 = memw_locked(%1);\n" \
+ " { P0 = cmp.eq(%0,%2);\n" \
+ " if (!P0.new) jump:nt 2f; }\n" \
+ " memw_locked(%1,p0) = %3;\n" \
+ " if (!P0) jump 1b;\n" \
+ "2:\n" \
+ : "=&r" (__oldval) \
+ : "r" (__ptr), "r" (__old), "r" (__new) \
+ : "memory", "p0" \
+ ); \
+ __oldval; \
+})
+
+#endif /* _ASM_CMPXCHG_H */