diff options
Diffstat (limited to 'arch/sparc/include')
| -rw-r--r-- | arch/sparc/include/asm/atomic_64.h | 4 | ||||
| -rw-r--r-- | arch/sparc/include/asm/backoff.h | 69 | ||||
| -rw-r--r-- | arch/sparc/include/asm/processor_64.h | 17 | ||||
| -rw-r--r-- | arch/sparc/include/asm/prom.h | 5 | ||||
| -rw-r--r-- | arch/sparc/include/uapi/asm/unistd.h | 3 |
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 |