[guv v2 19/31] ia64: Replace __get_cpu_var uses

From: Christoph Lameter
Date: Mon Aug 26 2013 - 16:51:01 EST

__get_cpu_var() is used for multiple purposes in the kernel source. One of them is
address calculation via the form &__get_cpu_var(x). This calculates the address for
the instance of the percpu variable of the current processor based on an offset.

Others usage cases are for storing and retrieving data from the current processors percpu area.
__get_cpu_var() can be used as an lvalue when writing data or on the right side of an assignment.

__get_cpu_var() is defined as :


#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))



__get_cpu_var() always only does a address determination. However, store and retrieve operations
could use a segment prefix (or global register on other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a percpu area and use
optimized assembly code to read and write per cpu variables.


This patch converts __get_cpu_var into either and explicit address calculation using this_cpu_ptr()
or into a use of this_cpu operations that use the offset. Thereby address calcualtions are avoided
and less registers are used when code is generated.

At the end of the patchset all uses of __get_cpu_var have been removed so the macro is removed too.

The patchset includes passes over all arches as well. Once these operations are used throughout then
specialized macros can be defined in non -x86 arches as well in order to optimize per cpu access by
f.e. using a global register that may be set to the per cpu base.




Transformations done to __get_cpu_var()


1. Determine the address of the percpu instance of the current processor.

DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);

Converts to

int *x = this_cpu_ptr(&y);


2. Same as #1 but this time an array structure is involved.

DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);

Converts to

int *x = this_cpu_ptr(y);


3. Retrieve the content of the current processors instance of a per cpu variable.

DEFINE_PER_CPU(int, u);
int x = __get_cpu_var(y)

Converts to

int x = __this_cpu_read(y);


4. Retrieve the content of a percpu struct

DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);

Converts to

memcpy(this_cpu_ptr(&y), x, sizeof(x));


5. Assignment to a per cpu variable

DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;

Converts to

this_cpu_write(y, x);


6. Increment/Decrement etc of a per cpu variable

DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++

Converts to

this_cpu_inc(y)



Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>

Index: linux/arch/alpha/kernel/perf_event.c
===================================================================
--- linux.orig/arch/alpha/kernel/perf_event.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/alpha/kernel/perf_event.c 2013-08-23 09:10:22.665620124 -0500
@@ -803,7 +803,7 @@ static void alpha_perf_event_irq_handler
struct hw_perf_event *hwc;
int idx, j;

- __get_cpu_var(irq_pmi_count)++;
+ __this_cpu_inc(irq_pmi_count);
cpuc = &__get_cpu_var(cpu_hw_events);

/* Completely counting through the PMC's period to trigger a new PMC
Index: linux/arch/ia64/kernel/irq.c
===================================================================
--- linux.orig/arch/ia64/kernel/irq.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/irq.c 2013-08-23 09:10:22.665620124 -0500
@@ -42,7 +42,7 @@ ia64_vector __ia64_irq_to_vector(int irq

unsigned int __ia64_local_vector_to_irq (ia64_vector vec)
{
- return __get_cpu_var(vector_irq)[vec];
+ return __this_cpu_read(vector_irq[vec]);
}
#endif

Index: linux/arch/ia64/kernel/irq_ia64.c
===================================================================
--- linux.orig/arch/ia64/kernel/irq_ia64.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/irq_ia64.c 2013-08-23 09:10:22.669620084 -0500
@@ -338,7 +338,7 @@ static irqreturn_t smp_irq_move_cleanup_
int irq;
struct irq_desc *desc;
struct irq_cfg *cfg;
- irq = __get_cpu_var(vector_irq)[vector];
+ irq = __this_cpu_read(vector_irq[vector]);
if (irq < 0)
continue;

@@ -352,7 +352,7 @@ static irqreturn_t smp_irq_move_cleanup_
goto unlock;

spin_lock_irqsave(&vector_lock, flags);
- __get_cpu_var(vector_irq)[vector] = -1;
+ __this_cpu_write(vector_irq[vector], -1);
cpu_clear(me, vector_table[vector]);
spin_unlock_irqrestore(&vector_lock, flags);
cfg->move_cleanup_count--;
Index: linux/arch/ia64/kernel/kprobes.c
===================================================================
--- linux.orig/arch/ia64/kernel/kprobes.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/kprobes.c 2013-08-23 09:10:22.669620084 -0500
@@ -396,7 +396,7 @@ static void __kprobes restore_previous_k
{
unsigned int i;
i = atomic_read(&kcb->prev_kprobe_index);
- __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i-1].kp;
+ __this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
atomic_sub(1, &kcb->prev_kprobe_index);
}
@@ -404,7 +404,7 @@ static void __kprobes restore_previous_k
static void __kprobes set_current_kprobe(struct kprobe *p,
struct kprobe_ctlblk *kcb)
{
- __get_cpu_var(current_kprobe) = p;
+ __this_cpu_write(current_kprobe, p);
}

static void kretprobe_trampoline(void)
@@ -823,7 +823,7 @@ static int __kprobes pre_kprobes_handler
/*
* jprobe instrumented function just completed
*/
- p = __get_cpu_var(current_kprobe);
+ p = __this_cpu_read(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;
}
Index: linux/arch/ia64/kernel/mca.c
===================================================================
--- linux.orig/arch/ia64/kernel/mca.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/mca.c 2013-08-23 09:11:54.244715775 -0500
@@ -1341,7 +1341,7 @@ ia64_mca_handler(struct pt_regs *regs, s
ia64_mlogbuf_finish(1);
}

- if (__get_cpu_var(ia64_mca_tr_reload)) {
+ if (__this_cpu_read(ia64_mca_tr_reload)) {
mca_insert_tr(0x1); /*Reload dynamic itrs*/
mca_insert_tr(0x2); /*Reload dynamic itrs*/
}
@@ -1874,14 +1874,14 @@ ia64_mca_cpu_init(void *cpu_data)
"MCA", cpu);
format_mca_init_stack(data, offsetof(struct ia64_mca_cpu, init_stack),
"INIT", cpu);
- __get_cpu_var(ia64_mca_data) = __per_cpu_mca[cpu] = __pa(data);
+ __this_cpu_write(ia64_mca_data, __per_cpu_mca[cpu] = __pa(data));

/*
* Stash away a copy of the PTE needed to map the per-CPU page.
* We may need it during MCA recovery.
*/
- __get_cpu_var(ia64_mca_per_cpu_pte) =
- pte_val(mk_pte_phys(__pa(cpu_data), PAGE_KERNEL));
+ __this_cpu_write(ia64_mca_per_cpu_pte,
+ pte_val(mk_pte_phys(__pa(cpu_data), PAGE_KERNEL)));

/*
* Also, stash away a copy of the PAL address and the PTE
@@ -1890,10 +1890,10 @@ ia64_mca_cpu_init(void *cpu_data)
pal_vaddr = efi_get_pal_addr();
if (!pal_vaddr)
return;
- __get_cpu_var(ia64_mca_pal_base) =
- GRANULEROUNDDOWN((unsigned long) pal_vaddr);
- __get_cpu_var(ia64_mca_pal_pte) = pte_val(mk_pte_phys(__pa(pal_vaddr),
- PAGE_KERNEL));
+ __this_cpu_write(ia64_mca_pal_base,
+ GRANULEROUNDDOWN((unsigned long) pal_vaddr));
+ __this_cpu_write(ia64_mca_pal_pte, pte_val(mk_pte_phys(__pa(pal_vaddr),
+ PAGE_KERNEL)));
}

static void ia64_mca_cmc_vector_adjust(void *dummy)
Index: linux/arch/ia64/kernel/process.c
===================================================================
--- linux.orig/arch/ia64/kernel/process.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/process.c 2013-08-23 09:10:22.669620084 -0500
@@ -215,7 +215,7 @@ static inline void play_dead(void)
unsigned int this_cpu = smp_processor_id();

/* Ack it */
- __get_cpu_var(cpu_state) = CPU_DEAD;
+ __this_cpu_write(cpu_state, CPU_DEAD);

max_xtp();
local_irq_disable();
@@ -273,7 +273,7 @@ ia64_save_extra (struct task_struct *tas
if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
pfm_save_regs(task);

- info = __get_cpu_var(pfm_syst_info);
+ info = __this_cpu_read(pfm_syst_info);
if (info & PFM_CPUINFO_SYST_WIDE)
pfm_syst_wide_update_task(task, info, 0);
#endif
@@ -293,7 +293,7 @@ ia64_load_extra (struct task_struct *tas
if ((task->thread.flags & IA64_THREAD_PM_VALID) != 0)
pfm_load_regs(task);

- info = __get_cpu_var(pfm_syst_info);
+ info = __this_cpu_read(pfm_syst_info);
if (info & PFM_CPUINFO_SYST_WIDE)
pfm_syst_wide_update_task(task, info, 1);
#endif
Index: linux/arch/ia64/sn/kernel/sn2/sn2_smp.c
===================================================================
--- linux.orig/arch/ia64/sn/kernel/sn2/sn2_smp.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/sn/kernel/sn2/sn2_smp.c 2013-08-23 09:10:22.669620084 -0500
@@ -134,8 +134,8 @@ sn2_ipi_flush_all_tlb(struct mm_struct *
itc = ia64_get_itc();
smp_flush_tlb_cpumask(*mm_cpumask(mm));
itc = ia64_get_itc() - itc;
- __get_cpu_var(ptcstats).shub_ipi_flushes_itc_clocks += itc;
- __get_cpu_var(ptcstats).shub_ipi_flushes++;
+ __this_cpu_add(ptcstats.shub_ipi_flushes_itc_clocks, itc);
+ __this_cpu_inc(ptcstats.shub_ipi_flushes);
}

/**
@@ -199,14 +199,14 @@ sn2_global_tlb_purge(struct mm_struct *m
start += (1UL << nbits);
} while (start < end);
ia64_srlz_i();
- __get_cpu_var(ptcstats).ptc_l++;
+ __this_cpu_inc(ptcstats.ptc_l);
preempt_enable();
return;
}

if (atomic_read(&mm->mm_users) == 1 && mymm) {
flush_tlb_mm(mm);
- __get_cpu_var(ptcstats).change_rid++;
+ __this_cpu_inc(ptcstats.change_rid);
preempt_enable();
return;
}
@@ -250,11 +250,11 @@ sn2_global_tlb_purge(struct mm_struct *m
spin_lock_irqsave(PTC_LOCK(shub1), flags);
itc2 = ia64_get_itc();

- __get_cpu_var(ptcstats).lock_itc_clocks += itc2 - itc;
- __get_cpu_var(ptcstats).shub_ptc_flushes++;
- __get_cpu_var(ptcstats).nodes_flushed += nix;
+ __this_cpu_add(ptcstats.lock_itc_clocks, itc2 - itc);
+ __this_cpu_inc(ptcstats.shub_ptc_flushes);
+ __this_cpu_add(ptcstats.nodes_flushed, nix);
if (!mymm)
- __get_cpu_var(ptcstats).shub_ptc_flushes_not_my_mm++;
+ __this_cpu_inc(ptcstats.shub_ptc_flushes_not_my_mm);

if (use_cpu_ptcga && !mymm) {
old_rr = ia64_get_rr(start);
@@ -299,9 +299,9 @@ sn2_global_tlb_purge(struct mm_struct *m

done:
itc2 = ia64_get_itc() - itc2;
- __get_cpu_var(ptcstats).shub_itc_clocks += itc2;
- if (itc2 > __get_cpu_var(ptcstats).shub_itc_clocks_max)
- __get_cpu_var(ptcstats).shub_itc_clocks_max = itc2;
+ __this_cpu_add(ptcstats)shub_itc_clocks, itc2);
+ if (itc2 > __this_cpu_read(ptcstats.shub_itc_clocks_max))
+ __this_cpu_write(ptcstats).shub_itc_clocks_max, itc2);

if (old_rr) {
ia64_set_rr(start, old_rr);
@@ -311,7 +311,7 @@ done:
spin_unlock_irqrestore(PTC_LOCK(shub1), flags);

if (flush_opt == 1 && deadlock) {
- __get_cpu_var(ptcstats).deadlocks++;
+ __this_cpu_inc(ptcstats.deadlocks);
sn2_ipi_flush_all_tlb(mm);
}

@@ -334,7 +334,7 @@ sn2_ptc_deadlock_recovery(short *nasids,
short nasid, i;
unsigned long *piows, zeroval, n;

- __get_cpu_var(ptcstats).deadlocks++;
+ __this_cpu_inc(ptcstats.deadlocks);

piows = (unsigned long *) pda->pio_write_status_addr;
zeroval = pda->pio_write_status_val;
@@ -349,7 +349,7 @@ sn2_ptc_deadlock_recovery(short *nasids,
ptc1 = CHANGE_NASID(nasid, ptc1);

n = sn2_ptc_deadlock_recovery_core(ptc0, data0, ptc1, data1, piows, zeroval);
- __get_cpu_var(ptcstats).deadlocks2 += n;
+ __this_cpu_add(ptcstats.deadlocks2, n);
}

}
Index: linux/arch/ia64/include/asm/hw_irq.h
===================================================================
--- linux.orig/arch/ia64/include/asm/hw_irq.h 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/include/asm/hw_irq.h 2013-08-23 09:10:22.673620044 -0500
@@ -160,7 +160,7 @@ static inline ia64_vector __ia64_irq_to_
static inline unsigned int
__ia64_local_vector_to_irq (ia64_vector vec)
{
- return __get_cpu_var(vector_irq)[vec];
+ return __this_cpu_read(vector_irq[vec]);
}
#endif

Index: linux/arch/ia64/include/asm/sn/nodepda.h
===================================================================
--- linux.orig/arch/ia64/include/asm/sn/nodepda.h 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/include/asm/sn/nodepda.h 2013-08-23 09:10:22.673620044 -0500
@@ -70,7 +70,7 @@ typedef struct nodepda_s nodepda_t;
*/

DECLARE_PER_CPU(struct nodepda_s *, __sn_nodepda);
-#define sn_nodepda (__get_cpu_var(__sn_nodepda))
+#define sn_nodepda __this_cpu_read(__sn_nodepda)
#define NODEPDA(cnodeid) (sn_nodepda->pernode_pdaindr[cnodeid])

/*
Index: linux/arch/ia64/include/asm/switch_to.h
===================================================================
--- linux.orig/arch/ia64/include/asm/switch_to.h 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/include/asm/switch_to.h 2013-08-23 09:10:22.673620044 -0500
@@ -32,7 +32,7 @@ extern void ia64_load_extra (struct task

#ifdef CONFIG_PERFMON
DECLARE_PER_CPU(unsigned long, pfm_syst_info);
-# define PERFMON_IS_SYSWIDE() (__get_cpu_var(pfm_syst_info) & 0x1)
+# define PERFMON_IS_SYSWIDE() (__this_cpu_read(pfm_syst_info) & 0x1)
#else
# define PERFMON_IS_SYSWIDE() (0)
#endif
Index: linux/arch/ia64/include/asm/sn/arch.h
===================================================================
--- linux.orig/arch/ia64/include/asm/sn/arch.h 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/include/asm/sn/arch.h 2013-08-23 09:10:22.673620044 -0500
@@ -57,7 +57,7 @@ struct sn_hub_info_s {
u16 nasid_bitmask;
};
DECLARE_PER_CPU(struct sn_hub_info_s, __sn_hub_info);
-#define sn_hub_info (&__get_cpu_var(__sn_hub_info))
+#define sn_hub_info this_cpu_ptr(&__sn_hub_info)
#define is_shub2() (sn_hub_info->shub2)
#define is_shub1() (sn_hub_info->shub2 == 0)

@@ -72,7 +72,7 @@ DECLARE_PER_CPU(struct sn_hub_info_s, __
* cpu.
*/
DECLARE_PER_CPU(short, __sn_cnodeid_to_nasid[MAX_COMPACT_NODES]);
-#define sn_cnodeid_to_nasid (&__get_cpu_var(__sn_cnodeid_to_nasid[0]))
+#define sn_cnodeid_to_nasid this_cpu_ptr(&__sn_cnodeid_to_nasid[0])


extern u8 sn_partition_id;
Index: linux/arch/ia64/include/asm/uv/uv_hub.h
===================================================================
--- linux.orig/arch/ia64/include/asm/uv/uv_hub.h 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/include/asm/uv/uv_hub.h 2013-08-23 09:10:22.673620044 -0500
@@ -108,7 +108,7 @@ struct uv_hub_info_s {
unsigned char n_val;
};
DECLARE_PER_CPU(struct uv_hub_info_s, __uv_hub_info);
-#define uv_hub_info (&__get_cpu_var(__uv_hub_info))
+#define uv_hub_info this_cpu_ptr(&__uv_hub_info)
#define uv_cpu_hub_info(cpu) (&per_cpu(__uv_hub_info, cpu))

/*
Index: linux/arch/ia64/kernel/traps.c
===================================================================
--- linux.orig/arch/ia64/kernel/traps.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/kernel/traps.c 2013-08-23 09:10:22.673620044 -0500
@@ -299,7 +299,7 @@ handle_fpu_swa (int fp_fault, struct pt_

if (!(current->thread.flags & IA64_THREAD_FPEMU_NOPRINT)) {
unsigned long count, current_jiffies = jiffies;
- struct fpu_swa_msg *cp = &__get_cpu_var(cpulast);
+ struct fpu_swa_msg *cp = this_cpu_ptr(&cpulast);

if (unlikely(current_jiffies > cp->time))
cp->count = 0;
Index: linux/arch/ia64/xen/time.c
===================================================================
--- linux.orig/arch/ia64/xen/time.c 2013-08-23 09:10:22.673620044 -0500
+++ linux/arch/ia64/xen/time.c 2013-08-23 09:10:22.673620044 -0500
@@ -68,7 +68,7 @@ static void get_runstate_snapshot(struct

BUG_ON(preemptible());

- state = &__get_cpu_var(xen_runstate);
+ state = this_cpu_ptr(&xen_runstate);

/*
* The runstate info is always updated by the hypervisor on

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