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authorAl Viro <viro@zeniv.linux.org.uk>2012-11-16 22:28:43 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2012-11-16 22:28:43 -0500
commit2bf81c8af92dd53890557c5d87875842d573a3e9 (patch)
tree83e7e3539599b091ac69557658c06c0a39cfa60e /arch/sparc/include
parent9526d9bc23f362035cfabf044aa90f4ed1787955 (diff)
parent5f6c4ab6ee781c9aace7c8548ad9bd87f5678df7 (diff)
downloadblackbird-op-linux-2bf81c8af92dd53890557c5d87875842d573a3e9.tar.gz
blackbird-op-linux-2bf81c8af92dd53890557c5d87875842d573a3e9.zip
Merge branch 'arch-microblaze' into no-rebases
Diffstat (limited to 'arch/sparc/include')
-rw-r--r--arch/sparc/include/asm/atomic_64.h4
-rw-r--r--arch/sparc/include/asm/backoff.h69
-rw-r--r--arch/sparc/include/asm/processor_64.h17
-rw-r--r--arch/sparc/include/asm/prom.h5
-rw-r--r--arch/sparc/include/uapi/asm/unistd.h3
5 files changed, 85 insertions, 13 deletions
diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h
index ce35a1cf1a20..be56a244c9cf 100644
--- a/arch/sparc/include/asm/atomic_64.h
+++ b/arch/sparc/include/asm/atomic_64.h
@@ -1,7 +1,7 @@
/* atomic.h: Thankfully the V9 is at least reasonable for this
* stuff.
*
- * Copyright (C) 1996, 1997, 2000 David S. Miller (davem@redhat.com)
+ * Copyright (C) 1996, 1997, 2000, 2012 David S. Miller (davem@redhat.com)
*/
#ifndef __ARCH_SPARC64_ATOMIC__
@@ -106,6 +106,8 @@ static inline long atomic64_add_unless(atomic64_t *v, long a, long u)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+extern long atomic64_dec_if_positive(atomic64_t *v);
+
/* Atomic operations are already serializing */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()
diff --git a/arch/sparc/include/asm/backoff.h b/arch/sparc/include/asm/backoff.h
index db3af0d30fb1..4e02086b839c 100644
--- a/arch/sparc/include/asm/backoff.h
+++ b/arch/sparc/include/asm/backoff.h
@@ -1,6 +1,46 @@
#ifndef _SPARC64_BACKOFF_H
#define _SPARC64_BACKOFF_H
+/* The macros in this file implement an exponential backoff facility
+ * for atomic operations.
+ *
+ * When multiple threads compete on an atomic operation, it is
+ * possible for one thread to be continually denied a successful
+ * completion of the compare-and-swap instruction. Heavily
+ * threaded cpu implementations like Niagara can compound this
+ * problem even further.
+ *
+ * When an atomic operation fails and needs to be retried, we spin a
+ * certain number of times. At each subsequent failure of the same
+ * operation we double the spin count, realizing an exponential
+ * backoff.
+ *
+ * When we spin, we try to use an operation that will cause the
+ * current cpu strand to block, and therefore make the core fully
+ * available to any other other runnable strands. There are two
+ * options, based upon cpu capabilities.
+ *
+ * On all cpus prior to SPARC-T4 we do three dummy reads of the
+ * condition code register. Each read blocks the strand for something
+ * between 40 and 50 cpu cycles.
+ *
+ * For SPARC-T4 and later we have a special "pause" instruction
+ * available. This is implemented using writes to register %asr27.
+ * The cpu will block the number of cycles written into the register,
+ * unless a disrupting trap happens first. SPARC-T4 specifically
+ * implements pause with a granularity of 8 cycles. Each strand has
+ * an internal pause counter which decrements every 8 cycles. So the
+ * chip shifts the %asr27 value down by 3 bits, and writes the result
+ * into the pause counter. If a value smaller than 8 is written, the
+ * chip blocks for 1 cycle.
+ *
+ * To achieve the same amount of backoff as the three %ccr reads give
+ * on earlier chips, we shift the backoff value up by 7 bits. (Three
+ * %ccr reads block for about 128 cycles, 1 << 7 == 128) We write the
+ * whole amount we want to block into the pause register, rather than
+ * loop writing 128 each time.
+ */
+
#define BACKOFF_LIMIT (4 * 1024)
#ifdef CONFIG_SMP
@@ -11,16 +51,25 @@
#define BACKOFF_LABEL(spin_label, continue_label) \
spin_label
-#define BACKOFF_SPIN(reg, tmp, label) \
- mov reg, tmp; \
-88: brnz,pt tmp, 88b; \
- sub tmp, 1, tmp; \
- set BACKOFF_LIMIT, tmp; \
- cmp reg, tmp; \
- bg,pn %xcc, label; \
- nop; \
- ba,pt %xcc, label; \
- sllx reg, 1, reg;
+#define BACKOFF_SPIN(reg, tmp, label) \
+ mov reg, tmp; \
+88: rd %ccr, %g0; \
+ rd %ccr, %g0; \
+ rd %ccr, %g0; \
+ .section .pause_3insn_patch,"ax";\
+ .word 88b; \
+ sllx tmp, 7, tmp; \
+ wr tmp, 0, %asr27; \
+ clr tmp; \
+ .previous; \
+ brnz,pt tmp, 88b; \
+ sub tmp, 1, tmp; \
+ set BACKOFF_LIMIT, tmp; \
+ cmp reg, tmp; \
+ bg,pn %xcc, label; \
+ nop; \
+ ba,pt %xcc, label; \
+ sllx reg, 1, reg;
#else
diff --git a/arch/sparc/include/asm/processor_64.h b/arch/sparc/include/asm/processor_64.h
index 0305d56d9b1a..cce72ce4c334 100644
--- a/arch/sparc/include/asm/processor_64.h
+++ b/arch/sparc/include/asm/processor_64.h
@@ -203,7 +203,22 @@ extern unsigned long get_wchan(struct task_struct *task);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->u_regs[UREG_FP])
-#define cpu_relax() barrier()
+/* Please see the commentary in asm/backoff.h for a description of
+ * what these instructions are doing and how they have been choosen.
+ * To make a long story short, we are trying to yield the current cpu
+ * strand during busy loops.
+ */
+#define cpu_relax() asm volatile("\n99:\n\t" \
+ "rd %%ccr, %%g0\n\t" \
+ "rd %%ccr, %%g0\n\t" \
+ "rd %%ccr, %%g0\n\t" \
+ ".section .pause_3insn_patch,\"ax\"\n\t"\
+ ".word 99b\n\t" \
+ "wr %%g0, 128, %%asr27\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ ".previous" \
+ ::: "memory")
/* Prefetch support. This is tuned for UltraSPARC-III and later.
* UltraSPARC-I will treat these as nops, and UltraSPARC-II has
diff --git a/arch/sparc/include/asm/prom.h b/arch/sparc/include/asm/prom.h
index c28765110706..f93003123bce 100644
--- a/arch/sparc/include/asm/prom.h
+++ b/arch/sparc/include/asm/prom.h
@@ -63,5 +63,10 @@ extern char *of_console_options;
extern void irq_trans_init(struct device_node *dp);
extern char *build_path_component(struct device_node *dp);
+/* SPARC has a local implementation */
+extern int of_address_to_resource(struct device_node *dev, int index,
+ struct resource *r);
+#define of_address_to_resource of_address_to_resource
+
#endif /* __KERNEL__ */
#endif /* _SPARC_PROM_H */
diff --git a/arch/sparc/include/uapi/asm/unistd.h b/arch/sparc/include/uapi/asm/unistd.h
index bed86a820d09..cac719d1bc5c 100644
--- a/arch/sparc/include/uapi/asm/unistd.h
+++ b/arch/sparc/include/uapi/asm/unistd.h
@@ -406,8 +406,9 @@
#define __NR_process_vm_readv 338
#define __NR_process_vm_writev 339
#define __NR_kern_features 340
+#define __NR_kcmp 341
-#define NR_syscalls 341
+#define NR_syscalls 342
/* Bitmask values returned from kern_features system call. */
#define KERN_FEATURE_MIXED_MODE_STACK 0x00000001
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