__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. Other use 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 an 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 an explicit address calculation using this_cpu_ptr() or into a use of this_cpu operations that use the offset. Thereby address calculations are avoided and less registers are used when code is generated. At the end of the patch set all uses of __get_cpu_var have been removed so the macro is removed too. The patch set 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, y); 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(&x, this_cpu_ptr(&y), 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) Cc: Ralf Baechle Signed-off-by: Christoph Lameter Index: linux/arch/mips/cavium-octeon/octeon-irq.c =================================================================== --- linux.orig/arch/mips/cavium-octeon/octeon-irq.c 2013-12-20 11:45:14.113574366 -0600 +++ linux/arch/mips/cavium-octeon/octeon-irq.c 2013-12-20 11:45:14.103574558 -0600 @@ -264,13 +264,13 @@ unsigned long *pen; unsigned long flags; union octeon_ciu_chip_data cd; - raw_spinlock_t *lock = &__get_cpu_var(octeon_irq_ciu_spinlock); + raw_spinlock_t *lock = this_cpu_ptr(&octeon_irq_ciu_spinlock); cd.p = irq_data_get_irq_chip_data(data); raw_spin_lock_irqsave(lock, flags); if (cd.s.line == 0) { - pen = &__get_cpu_var(octeon_irq_ciu0_en_mirror); + pen = this_cpu_ptr(&octeon_irq_ciu0_en_mirror); __set_bit(cd.s.bit, pen); /* * Must be visible to octeon_irq_ip{2,3}_ciu() before @@ -279,7 +279,7 @@ wmb(); cvmx_write_csr(CVMX_CIU_INTX_EN0(cvmx_get_core_num() * 2), *pen); } else { - pen = &__get_cpu_var(octeon_irq_ciu1_en_mirror); + pen = this_cpu_ptr(&octeon_irq_ciu1_en_mirror); __set_bit(cd.s.bit, pen); /* * Must be visible to octeon_irq_ip{2,3}_ciu() before @@ -296,13 +296,13 @@ unsigned long *pen; unsigned long flags; union octeon_ciu_chip_data cd; - raw_spinlock_t *lock = &__get_cpu_var(octeon_irq_ciu_spinlock); + raw_spinlock_t *lock = this_cpu_ptr(&octeon_irq_ciu_spinlock); cd.p = irq_data_get_irq_chip_data(data); raw_spin_lock_irqsave(lock, flags); if (cd.s.line == 0) { - pen = &__get_cpu_var(octeon_irq_ciu0_en_mirror); + pen = this_cpu_ptr(&octeon_irq_ciu0_en_mirror); __clear_bit(cd.s.bit, pen); /* * Must be visible to octeon_irq_ip{2,3}_ciu() before @@ -311,7 +311,7 @@ wmb(); cvmx_write_csr(CVMX_CIU_INTX_EN0(cvmx_get_core_num() * 2), *pen); } else { - pen = &__get_cpu_var(octeon_irq_ciu1_en_mirror); + pen = this_cpu_ptr(&octeon_irq_ciu1_en_mirror); __clear_bit(cd.s.bit, pen); /* * Must be visible to octeon_irq_ip{2,3}_ciu() before @@ -431,11 +431,11 @@ if (cd.s.line == 0) { int index = cvmx_get_core_num() * 2; - set_bit(cd.s.bit, &__get_cpu_var(octeon_irq_ciu0_en_mirror)); + set_bit(cd.s.bit, this_cpu_ptr(&octeon_irq_ciu0_en_mirror)); cvmx_write_csr(CVMX_CIU_INTX_EN0_W1S(index), mask); } else { int index = cvmx_get_core_num() * 2 + 1; - set_bit(cd.s.bit, &__get_cpu_var(octeon_irq_ciu1_en_mirror)); + set_bit(cd.s.bit, this_cpu_ptr(&octeon_irq_ciu1_en_mirror)); cvmx_write_csr(CVMX_CIU_INTX_EN1_W1S(index), mask); } } @@ -450,11 +450,11 @@ if (cd.s.line == 0) { int index = cvmx_get_core_num() * 2; - clear_bit(cd.s.bit, &__get_cpu_var(octeon_irq_ciu0_en_mirror)); + clear_bit(cd.s.bit, this_cpu_ptr(&octeon_irq_ciu0_en_mirror)); cvmx_write_csr(CVMX_CIU_INTX_EN0_W1C(index), mask); } else { int index = cvmx_get_core_num() * 2 + 1; - clear_bit(cd.s.bit, &__get_cpu_var(octeon_irq_ciu1_en_mirror)); + clear_bit(cd.s.bit, this_cpu_ptr(&octeon_irq_ciu1_en_mirror)); cvmx_write_csr(CVMX_CIU_INTX_EN1_W1C(index), mask); } } @@ -1063,7 +1063,7 @@ const unsigned long core_id = cvmx_get_core_num(); u64 ciu_sum = cvmx_read_csr(CVMX_CIU_INTX_SUM0(core_id * 2)); - ciu_sum &= __get_cpu_var(octeon_irq_ciu0_en_mirror); + ciu_sum &= __this_cpu_read(octeon_irq_ciu0_en_mirror); if (likely(ciu_sum)) { int bit = fls64(ciu_sum) - 1; int irq = octeon_irq_ciu_to_irq[0][bit]; @@ -1080,7 +1080,7 @@ { u64 ciu_sum = cvmx_read_csr(CVMX_CIU_INT_SUM1); - ciu_sum &= __get_cpu_var(octeon_irq_ciu1_en_mirror); + ciu_sum &= __this_cpu_read(octeon_irq_ciu1_en_mirror); if (likely(ciu_sum)) { int bit = fls64(ciu_sum) - 1; int irq = octeon_irq_ciu_to_irq[1][bit]; @@ -1129,10 +1129,10 @@ int coreid = cvmx_get_core_num(); - __get_cpu_var(octeon_irq_ciu0_en_mirror) = 0; - __get_cpu_var(octeon_irq_ciu1_en_mirror) = 0; + __this_cpu_write(octeon_irq_ciu0_en_mirror, 0); + __this_cpu_write(octeon_irq_ciu1_en_mirror, 0); wmb(); - raw_spin_lock_init(&__get_cpu_var(octeon_irq_ciu_spinlock)); + raw_spin_lock_init(this_cpu_ptr(&octeon_irq_ciu_spinlock)); /* * Disable All CIU Interrupts. The ones we need will be * enabled later. Read the SUM register so we know the write Index: linux/arch/mips/kernel/kprobes.c =================================================================== --- linux.orig/arch/mips/kernel/kprobes.c 2013-12-20 11:45:14.113574366 -0600 +++ linux/arch/mips/kernel/kprobes.c 2013-12-20 11:45:14.103574558 -0600 @@ -224,7 +224,7 @@ static void restore_previous_kprobe(struct kprobe_ctlblk *kcb) { - __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); kcb->kprobe_status = kcb->prev_kprobe.status; kcb->kprobe_old_SR = kcb->prev_kprobe.old_SR; kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR; @@ -234,7 +234,7 @@ static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { - __get_cpu_var(current_kprobe) = p; + __this_cpu_write(current_kprobe, p); kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE); kcb->kprobe_saved_epc = regs->cp0_epc; } @@ -385,7 +385,7 @@ ret = 1; goto no_kprobe; } - 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/mips/kernel/perf_event_mipsxx.c =================================================================== --- linux.orig/arch/mips/kernel/perf_event_mipsxx.c 2013-12-20 11:45:14.113574366 -0600 +++ linux/arch/mips/kernel/perf_event_mipsxx.c 2013-12-20 11:45:14.103574558 -0600 @@ -340,7 +340,7 @@ static void mipsxx_pmu_enable_event(struct hw_perf_event *evt, int idx) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); WARN_ON(idx < 0 || idx >= mipspmu.num_counters); @@ -360,7 +360,7 @@ static void mipsxx_pmu_disable_event(int idx) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); unsigned long flags; WARN_ON(idx < 0 || idx >= mipspmu.num_counters); @@ -460,7 +460,7 @@ static int mipspmu_add(struct perf_event *event, int flags) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); struct hw_perf_event *hwc = &event->hw; int idx; int err = 0; @@ -496,7 +496,7 @@ static void mipspmu_del(struct perf_event *event, int flags) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); struct hw_perf_event *hwc = &event->hw; int idx = hwc->idx; @@ -1270,7 +1270,7 @@ static void pause_local_counters(void) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); int ctr = mipspmu.num_counters; unsigned long flags; @@ -1286,7 +1286,7 @@ static void resume_local_counters(void) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); int ctr = mipspmu.num_counters; do { @@ -1297,7 +1297,7 @@ static int mipsxx_pmu_handle_shared_irq(void) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); struct perf_sample_data data; unsigned int counters = mipspmu.num_counters; u64 counter; Index: linux/arch/mips/kernel/smp-bmips.c =================================================================== --- linux.orig/arch/mips/kernel/smp-bmips.c 2013-12-20 11:45:14.113574366 -0600 +++ linux/arch/mips/kernel/smp-bmips.c 2013-12-20 11:45:14.103574558 -0600 @@ -304,7 +304,7 @@ int action, cpu = irq - IPI0_IRQ; spin_lock_irqsave(&ipi_lock, flags); - action = __get_cpu_var(ipi_action_mask); + action = __this_cpu_read(ipi_action_mask); per_cpu(ipi_action_mask, cpu) = 0; clear_c0_cause(cpu ? C_SW1 : C_SW0); spin_unlock_irqrestore(&ipi_lock, flags); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/