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Subject[patch 35/41] Support for CPU ops
IA64 has no efficient atomic operations. But we can get rid of the need to
add my_percpu_offset(). The address of a per cpu variable can be used directly
on IA64 since its mapped to a per processor area.

This also allows us to kill off the __ia64_get_cpu_var macro. Its nothing but
per_cpu_var().

Cc: Tony.Luck@intel.com
Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
arch/ia64/Kconfig | 3
arch/ia64/kernel/perfmon.c | 2
arch/ia64/kernel/setup.c | 2
arch/ia64/kernel/smp.c | 4 -
arch/ia64/sn/kernel/setup.c | 4 -
include/asm-ia64/mmu_context.h | 6 -
include/asm-ia64/percpu.h | 133 ++++++++++++++++++++++++++++++++++++++---
include/asm-ia64/processor.h | 2
include/asm-ia64/sn/pda.h | 2
9 files changed, 138 insertions(+), 20 deletions(-)

Index: linux-2.6/include/asm-ia64/percpu.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/percpu.h 2008-05-29 19:35:10.000000000 -0700
+++ linux-2.6/include/asm-ia64/percpu.h 2008-05-29 19:35:11.000000000 -0700
@@ -19,7 +19,7 @@
# define PER_CPU_ATTRIBUTES __attribute__((__model__ (__small__)))
#endif

-#define __my_cpu_offset __ia64_per_cpu_var(local_per_cpu_offset)
+#define __my_cpu_offset CPU_READ(per_cpu_var(local_per_cpu_offset))

extern void *per_cpu_init(void);

@@ -31,14 +31,6 @@ extern void *per_cpu_init(void);

#endif /* SMP */

-/*
- * Be extremely careful when taking the address of this variable! Due to virtual
- * remapping, it is different from the canonical address returned by __get_cpu_var(var)!
- * On the positive side, using __ia64_per_cpu_var() instead of __get_cpu_var() is slightly
- * more efficient.
- */
-#define __ia64_per_cpu_var(var) per_cpu__##var
-
#include <asm-generic/percpu.h>

/* Equal to __per_cpu_offset[smp_processor_id()], but faster to access: */
@@ -46,4 +38,127 @@ DECLARE_PER_CPU(unsigned long, local_per

#endif /* !__ASSEMBLY__ */

+/*
+ * Per cpu ops.
+ *
+ * IA64 has no instructions that would allow light weight RMW operations.
+ *
+ * However, the canonical address of a per cpu variable is mapped via
+ * a processor specific TLB entry to the per cpu area of the respective
+ * processor. The THIS_CPU() macro is therefore not necessary here
+ * since the canonical address of the per cpu variable allows access
+ * to the instance of the per cpu variable for the current processor.
+ *
+ * Sadly we cannot simply define THIS_CPU() to return an address in
+ * the per processor mapping space since the address acquired by THIS_CPU\
+ * may be passed to another processor.
+ */
+#define __CPU_READ(var) \
+({ \
+ (var); \
+})
+
+#define __CPU_WRITE(var, value) \
+({ \
+ (var) = (value); \
+})
+
+#define __CPU_ADD(var, value) \
+({ \
+ (var) += (value); \
+})
+
+#define __CPU_INC(var) __CPU_ADD((var), 1)
+#define __CPU_DEC(var) __CPU_ADD((var), -1)
+#define __CPU_SUB(var, value) __CPU_ADD((var), -(value))
+
+#define __CPU_CMPXCHG(var, old, new) \
+({ \
+ typeof(obj) x; \
+ typeof(obj) *p = &(var); \
+ x = *p; \
+ if (x == (old)) \
+ *p = (new); \
+ (x); \
+})
+
+#define __CPU_XCHG(obj, new) \
+({ \
+ typeof(obj) x; \
+ typeof(obj) *p = &(obj); \
+ x = *p; \
+ *p = (new); \
+ (x); \
+})
+
+#define _CPU_READ __CPU_READ
+#define _CPU_WRITE __CPU_WRITE
+
+#define _CPU_ADD(var, value) \
+({ \
+ preempt_disable(); \
+ __CPU_ADD((var), (value)); \
+ preempt_enable(); \
+})
+
+#define _CPU_INC(var) _CPU_ADD((var), 1)
+#define _CPU_DEC(var) _CPU_ADD((var), -1)
+#define _CPU_SUB(var, value) _CPU_ADD((var), -(value))
+
+#define _CPU_CMPXCHG(var, old, new) \
+({ \
+ typeof(addr) x; \
+ preempt_disable(); \
+ x = __CPU_CMPXCHG((var), (old), (new)); \
+ preempt_enable(); \
+ (x); \
+})
+
+#define _CPU_XCHG(var, new) \
+({ \
+ typeof(var) x; \
+ preempt_disable(); \
+ x = __CPU_XCHG((var), (new)); \
+ preempt_enable(); \
+ (x); \
+})
+
+/*
+ * Third group: Interrupt safe CPU functions
+ */
+#define CPU_READ __CPU_READ
+#define CPU_WRITE __CPU_WRITE
+
+#define CPU_ADD(var, value) \
+({ \
+ unsigned long flags; \
+ local_irq_save(flags); \
+ __CPU_ADD((var), (value)); \
+ local_irq_restore(flags); \
+})
+
+#define CPU_INC(var) CPU_ADD((var), 1)
+#define CPU_DEC(var) CPU_ADD((var), -1)
+#define CPU_SUB(var, value) CPU_ADD((var), -(value))
+
+#define CPU_CMPXCHG(var, old, new) \
+({ \
+ unsigned long flags; \
+ typeof(var) x; \
+ local_irq_save(flags); \
+ x = __CPU_CMPXCHG((var), (old), (new)); \
+ local_irq_restore(flags); \
+ (x); \
+})
+
+#define CPU_XCHG(var, new) \
+({ \
+ unsigned long flags; \
+ typeof(var) x; \
+ local_irq_save(flags); \
+ x = __CPU_XCHG((var), (new)); \
+ local_irq_restore(flags); \
+ (x); \
+})
+
#endif /* _ASM_IA64_PERCPU_H */
Index: linux-2.6/arch/ia64/kernel/perfmon.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/perfmon.c 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/arch/ia64/kernel/perfmon.c 2008-05-29 19:35:13.000000000 -0700
@@ -576,7 +576,7 @@ static struct ctl_table_header *pfm_sysc

static int pfm_context_unload(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs);

-#define pfm_get_cpu_var(v) __ia64_per_cpu_var(v)
+#define pfm_get_cpu_var(v) per_cpu_var(v)
#define pfm_get_cpu_data(a,b) per_cpu(a, b)

static inline void
Index: linux-2.6/arch/ia64/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/setup.c 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/arch/ia64/kernel/setup.c 2008-05-29 19:35:11.000000000 -0700
@@ -925,7 +925,7 @@ cpu_init (void)
* depends on the data returned by identify_cpu(). We break the dependency by
* accessing cpu_data() through the canonical per-CPU address.
*/
- cpu_info = cpu_data + ((char *) &__ia64_per_cpu_var(cpu_info) - __per_cpu_start);
+ cpu_info = cpu_data + ((char *)&per_cpu_var(cpu_info) - __per_cpu_start);
identify_cpu(cpu_info);

#ifdef CONFIG_MCKINLEY
Index: linux-2.6/arch/ia64/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/smp.c 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/arch/ia64/kernel/smp.c 2008-05-29 19:35:11.000000000 -0700
@@ -150,7 +150,7 @@ irqreturn_t
handle_IPI (int irq, void *dev_id)
{
int this_cpu = get_cpu();
- unsigned long *pending_ipis = &__ia64_per_cpu_var(ipi_operation);
+ unsigned long *pending_ipis = &per_cpu_var(ipi_operation);
unsigned long ops;

mb(); /* Order interrupt and bit testing. */
@@ -303,7 +303,7 @@ smp_local_flush_tlb(void)
void
smp_flush_tlb_cpumask(cpumask_t xcpumask)
{
- unsigned int *counts = __ia64_per_cpu_var(shadow_flush_counts);
+ unsigned int *counts = per_cpu_var(shadow_flush_counts);
cpumask_t cpumask = xcpumask;
int mycpu, cpu, flush_mycpu = 0;

Index: linux-2.6/arch/ia64/sn/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/ia64/sn/kernel/setup.c 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/arch/ia64/sn/kernel/setup.c 2008-05-29 19:35:11.000000000 -0700
@@ -645,7 +645,7 @@ void __cpuinit sn_cpu_init(void)
/* copy cpu 0's sn_cnodeid_to_nasid table to this cpu's */
memcpy(sn_cnodeid_to_nasid,
(&per_cpu(__sn_cnodeid_to_nasid, 0)),
- sizeof(__ia64_per_cpu_var(__sn_cnodeid_to_nasid)));
+ sizeof(per_cpu_var(__sn_cnodeid_to_nasid)));
}

/*
@@ -706,7 +706,7 @@ void __init build_cnode_tables(void)

memset(physical_node_map, -1, sizeof(physical_node_map));
memset(sn_cnodeid_to_nasid, -1,
- sizeof(__ia64_per_cpu_var(__sn_cnodeid_to_nasid)));
+ sizeof(per_cpu_var(__sn_cnodeid_to_nasid)));

/*
* First populate the tables with C/M bricks. This ensures that
Index: linux-2.6/include/asm-ia64/mmu_context.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/mmu_context.h 2008-05-29 19:35:10.000000000 -0700
+++ linux-2.6/include/asm-ia64/mmu_context.h 2008-05-29 19:35:13.000000000 -0700
@@ -64,11 +64,11 @@ delayed_tlb_flush (void)
extern void local_flush_tlb_all (void);
unsigned long flags;

- if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
+ if (unlikely(CPU_READ(per_cpu_var(ia64_need_tlb_flush)))) {
spin_lock_irqsave(&ia64_ctx.lock, flags);
- if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
+ if (CPU_READ(per_cpu_var(ia64_need_tlb_flush))) {
local_flush_tlb_all();
- __ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
+ CPU_WRITE(per_cpu_var(ia64_need_tlb_flush), 0);
}
spin_unlock_irqrestore(&ia64_ctx.lock, flags);
}
Index: linux-2.6/include/asm-ia64/processor.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/processor.h 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/include/asm-ia64/processor.h 2008-05-29 19:35:11.000000000 -0700
@@ -237,7 +237,7 @@ DECLARE_PER_CPU(struct cpuinfo_ia64, cpu
* Do not use the address of local_cpu_data, since it will be different from
* cpu_data(smp_processor_id())!
*/
-#define local_cpu_data (&__ia64_per_cpu_var(cpu_info))
+#define local_cpu_data (&per_cpu_var(cpu_info))
#define cpu_data(cpu) (&per_cpu(cpu_info, cpu))

extern void print_cpu_info (struct cpuinfo_ia64 *);
Index: linux-2.6/include/asm-ia64/sn/pda.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/sn/pda.h 2008-05-29 19:35:10.000000000 -0700
+++ linux-2.6/include/asm-ia64/sn/pda.h 2008-05-29 19:35:11.000000000 -0700
@@ -62,7 +62,7 @@ typedef struct pda_s {
*/
DECLARE_PER_CPU(struct pda_s, pda_percpu);

-#define pda (&__ia64_per_cpu_var(pda_percpu))
+#define pda (&per_cpu_var(pda_percpu))

#define pdacpu(cpu) (&per_cpu(pda_percpu, cpu))

Index: linux-2.6/arch/ia64/Kconfig
===================================================================
--- linux-2.6.orig/arch/ia64/Kconfig 2008-05-29 19:35:09.000000000 -0700
+++ linux-2.6/arch/ia64/Kconfig 2008-05-29 19:35:11.000000000 -0700
@@ -92,6 +92,9 @@ config GENERIC_TIME_VSYSCALL
config HAVE_SETUP_PER_CPU_AREA
def_bool y

+config HAVE_CPU_OPS
+ def_bool y
+
config DMI
bool
default y
--


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