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Subject[PATCH 1/3] x86-64: Convert the PDA to percpu.
Date
This patch makes the PDA a normal per-cpu variable, allowing the
removal of the special allocator code. %gs still points to the
base of the PDA.

Tested on a dual-core AMD64 system.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/include/asm/pda.h | 3 --
arch/x86/include/asm/percpu.h | 3 --
arch/x86/include/asm/setup.h | 1 -
arch/x86/kernel/cpu/common.c | 6 ++--
arch/x86/kernel/dumpstack_64.c | 8 ++--
arch/x86/kernel/head64.c | 23 +------------
arch/x86/kernel/irq.c | 2 +-
arch/x86/kernel/nmi.c | 2 +-
arch/x86/kernel/setup_percpu.c | 70 ++++++++--------------------------------
arch/x86/kernel/smpboot.c | 58 +--------------------------------
arch/x86/xen/enlighten.c | 2 +-
arch/x86/xen/smp.c | 12 +------
12 files changed, 27 insertions(+), 163 deletions(-)

diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
index 2fbfff8..b008127 100644
--- a/arch/x86/include/asm/pda.h
+++ b/arch/x86/include/asm/pda.h
@@ -39,11 +39,8 @@ struct x8664_pda {
unsigned irq_spurious_count;
} ____cacheline_aligned_in_smp;

-extern struct x8664_pda **_cpu_pda;
extern void pda_init(int);

-#define cpu_pda(i) (_cpu_pda[i])
-
/*
* There is no fast way to get the base address of the PDA, all the accesses
* have to mention %fs/%gs. So it needs to be done this Torvaldian way.
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index ece7205..6f866fd 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -12,11 +12,8 @@
#ifdef CONFIG_SMP
#include <asm/pda.h>

-#define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
#define __my_cpu_offset read_pda(data_offset)

-#define per_cpu_offset(x) (__per_cpu_offset(x))
-
#endif
#include <asm-generic/percpu.h>

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f12d372..b751aaf 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -93,7 +93,6 @@ extern unsigned long init_pg_tables_start;
extern unsigned long init_pg_tables_end;

#else
-void __init x86_64_init_pda(void);
void __init x86_64_start_kernel(char *real_mode);
void __init x86_64_start_reservations(char *real_mode_data);

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index b9c9ea0..7d741ef 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -857,8 +857,8 @@ __setup("clearcpuid=", setup_disablecpuid);
cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;

#ifdef CONFIG_X86_64
-struct x8664_pda **_cpu_pda __read_mostly;
-EXPORT_SYMBOL(_cpu_pda);
+DEFINE_PER_CPU_PAGE_ALIGNED(struct x8664_pda, pda);
+EXPORT_PER_CPU_SYMBOL(pda);

struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };

@@ -866,7 +866,7 @@ char boot_cpu_stack[IRQSTACKSIZE] __page_aligned_bss;

void __cpuinit pda_init(int cpu)
{
- struct x8664_pda *pda = cpu_pda(cpu);
+ struct x8664_pda *pda = &per_cpu(pda, cpu);

/* Setup up data that may be needed in __get_free_pages early */
loadsegment(fs, 0);
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 96a5db7..1098b21 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -163,7 +163,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
const struct stacktrace_ops *ops, void *data)
{
const unsigned cpu = get_cpu();
- unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
+ unsigned long *irqstack_end = (unsigned long *)per_cpu(pda, cpu).irqstackptr;
unsigned used = 0;
struct thread_info *tinfo;

@@ -306,9 +306,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
int i;
const int cpu = smp_processor_id();
unsigned long *irqstack_end =
- (unsigned long *) (cpu_pda(cpu)->irqstackptr);
+ (unsigned long *) (per_cpu(pda, cpu).irqstackptr);
unsigned long *irqstack =
- (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);
+ (unsigned long *) (per_cpu(pda, cpu).irqstackptr - IRQSTACKSIZE);

/*
* debugging aid: "show_stack(NULL, NULL);" prints the
@@ -374,7 +374,7 @@ void show_registers(struct pt_regs *regs)
int i;
unsigned long sp;
const int cpu = smp_processor_id();
- struct task_struct *cur = cpu_pda(cpu)->pcurrent;
+ struct task_struct *cur = per_cpu(pda, cpu).pcurrent;

sp = regs->sp;
printk("CPU %d ", cpu);
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index d16084f..274e2a9 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -25,27 +25,6 @@
#include <asm/e820.h>
#include <asm/bios_ebda.h>

-/* boot cpu pda */
-static struct x8664_pda _boot_cpu_pda __read_mostly;
-
-#ifdef CONFIG_SMP
-/*
- * We install an empty cpu_pda pointer table to indicate to early users
- * (numa_set_node) that the cpu_pda pointer table for cpus other than
- * the boot cpu is not yet setup.
- */
-static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata;
-#else
-static struct x8664_pda *__cpu_pda[NR_CPUS] __read_mostly;
-#endif
-
-void __init x86_64_init_pda(void)
-{
- _cpu_pda = __cpu_pda;
- cpu_pda(0) = &_boot_cpu_pda;
- pda_init(0);
-}
-
static void __init zap_identity_mappings(void)
{
pgd_t *pgd = pgd_offset_k(0UL);
@@ -111,7 +90,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
if (console_loglevel == 10)
early_printk("Kernel alive\n");

- x86_64_init_pda();
+ pda_init(0);

x86_64_start_reservations(real_mode_data);
}
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index d1d4dc5..066e680 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -38,7 +38,7 @@ void ack_bad_irq(unsigned int irq)
#ifdef CONFIG_X86_32
# define irq_stats(x) (&per_cpu(irq_stat, x))
#else
-# define irq_stats(x) cpu_pda(x)
+# define irq_stats(x) (&per_cpu(pda, x))
#endif
/*
* /proc/interrupts printing:
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 2c97f07..4a5bb40 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -64,7 +64,7 @@ static int endflag __initdata;
static inline unsigned int get_nmi_count(int cpu)
{
#ifdef CONFIG_X86_64
- return cpu_pda(cpu)->__nmi_count;
+ return per_cpu(pda, cpu).__nmi_count;
#else
return nmi_count(cpu);
#endif
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index ae0c0d3..fb0ccdc 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -80,58 +80,8 @@ static void __init setup_per_cpu_maps(void)
#endif
}

-#ifdef CONFIG_X86_32
-/*
- * Great future not-so-futuristic plan: make i386 and x86_64 do it
- * the same way
- */
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
-static inline void setup_cpu_pda_map(void) { }
-
-#elif !defined(CONFIG_SMP)
-static inline void setup_cpu_pda_map(void) { }
-
-#else /* CONFIG_SMP && CONFIG_X86_64 */
-
-/*
- * Allocate cpu_pda pointer table and array via alloc_bootmem.
- */
-static void __init setup_cpu_pda_map(void)
-{
- char *pda;
- struct x8664_pda **new_cpu_pda;
- unsigned long size;
- int cpu;
-
- size = roundup(sizeof(struct x8664_pda), cache_line_size());
-
- /* allocate cpu_pda array and pointer table */
- {
- unsigned long tsize = nr_cpu_ids * sizeof(void *);
- unsigned long asize = size * (nr_cpu_ids - 1);
-
- tsize = roundup(tsize, cache_line_size());
- new_cpu_pda = alloc_bootmem(tsize + asize);
- pda = (char *)new_cpu_pda + tsize;
- }
-
- /* initialize pointer table to static pda's */
- for_each_possible_cpu(cpu) {
- if (cpu == 0) {
- /* leave boot cpu pda in place */
- new_cpu_pda[0] = cpu_pda(0);
- continue;
- }
- new_cpu_pda[cpu] = (struct x8664_pda *)pda;
- new_cpu_pda[cpu]->in_bootmem = 1;
- pda += size;
- }
-
- /* point to new pointer table */
- _cpu_pda = new_cpu_pda;
-}
-#endif

/*
* Great future plan:
@@ -145,9 +95,6 @@ void __init setup_per_cpu_areas(void)
int cpu;
unsigned long align = 1;

- /* Setup cpu_pda map */
- setup_cpu_pda_map();
-
/* Copy section for each CPU (we discard the original) */
old_size = PERCPU_ENOUGH_ROOM;
align = max_t(unsigned long, PAGE_SIZE, align);
@@ -179,10 +126,21 @@ void __init setup_per_cpu_areas(void)
cpu, node, __pa(ptr));
}
#endif
- per_cpu_offset(cpu) = ptr - __per_cpu_start;
+ __per_cpu_offset[cpu] = ptr - __per_cpu_start;
memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
+#ifdef CONFIG_X86_64
+ if (cpu)
+ memset(&per_cpu(pda, cpu), 0, sizeof(struct x8664_pda));
+ per_cpu(pda, cpu).data_offset = __per_cpu_offset[cpu];
+#endif
}

+#ifdef CONFIG_X86_64
+ mb();
+ wrmsrl(MSR_GS_BASE, &per_cpu(pda, 0));
+ mb();
+#endif
+
printk(KERN_DEBUG "NR_CPUS: %d, nr_cpu_ids: %d, nr_node_ids %d\n",
NR_CPUS, nr_cpu_ids, nr_node_ids);

@@ -229,8 +187,8 @@ void __cpuinit numa_set_node(int cpu, int node)
{
int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);

- if (cpu_pda(cpu) && node != NUMA_NO_NODE)
- cpu_pda(cpu)->nodenumber = node;
+ if (node != NUMA_NO_NODE)
+ per_cpu(pda, cpu).nodenumber = node;

if (cpu_to_node_map)
cpu_to_node_map[cpu] = node;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f71f96f..d25b989 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -753,52 +753,6 @@ static void __cpuinit do_fork_idle(struct work_struct *work)
complete(&c_idle->done);
}

-#ifdef CONFIG_X86_64
-
-/* __ref because it's safe to call free_bootmem when after_bootmem == 0. */
-static void __ref free_bootmem_pda(struct x8664_pda *oldpda)
-{
- if (!after_bootmem)
- free_bootmem((unsigned long)oldpda, sizeof(*oldpda));
-}
-
-/*
- * Allocate node local memory for the AP pda.
- *
- * Must be called after the _cpu_pda pointer table is initialized.
- */
-int __cpuinit get_local_pda(int cpu)
-{
- struct x8664_pda *oldpda, *newpda;
- unsigned long size = sizeof(struct x8664_pda);
- int node = cpu_to_node(cpu);
-
- if (cpu_pda(cpu) && !cpu_pda(cpu)->in_bootmem)
- return 0;
-
- oldpda = cpu_pda(cpu);
- newpda = kmalloc_node(size, GFP_ATOMIC, node);
- if (!newpda) {
- printk(KERN_ERR "Could not allocate node local PDA "
- "for CPU %d on node %d\n", cpu, node);
-
- if (oldpda)
- return 0; /* have a usable pda */
- else
- return -1;
- }
-
- if (oldpda) {
- memcpy(newpda, oldpda, size);
- free_bootmem_pda(oldpda);
- }
-
- newpda->in_bootmem = 0;
- cpu_pda(cpu) = newpda;
- return 0;
-}
-#endif /* CONFIG_X86_64 */
-
static int __cpuinit do_boot_cpu(int apicid, int cpu)
/*
* NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
@@ -816,16 +770,6 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
};
INIT_WORK(&c_idle.work, do_fork_idle);

-#ifdef CONFIG_X86_64
- /* Allocate node local memory for AP pdas */
- if (cpu > 0) {
- boot_error = get_local_pda(cpu);
- if (boot_error)
- goto restore_state;
- /* if can't get pda memory, can't start cpu */
- }
-#endif
-
alternatives_smp_switch(1);

c_idle.idle = get_idle_for_cpu(cpu);
@@ -861,7 +805,7 @@ do_rest:
/* Stack for startup_32 can be just as for start_secondary onwards */
irq_ctx_init(cpu);
#else
- cpu_pda(cpu)->pcurrent = c_idle.idle;
+ per_cpu(pda, cpu).pcurrent = c_idle.idle;
clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
#endif
early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5e4686d..0160bb6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1649,7 +1649,7 @@ asmlinkage void __init xen_start_kernel(void)
#ifdef CONFIG_X86_64
/* Disable until direct per-cpu data access. */
have_vcpu_info_placement = 0;
- x86_64_init_pda();
+ pda_init(0);
#endif

xen_smp_init();
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index acd9b67..17823cb 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -280,22 +280,12 @@ static int __cpuinit xen_cpu_up(unsigned int cpu)
struct task_struct *idle = idle_task(cpu);
int rc;

-#ifdef CONFIG_X86_64
- /* Allocate node local memory for AP pdas */
- WARN_ON(cpu == 0);
- if (cpu > 0) {
- rc = get_local_pda(cpu);
- if (rc)
- return rc;
- }
-#endif
-
#ifdef CONFIG_X86_32
init_gdt(cpu);
per_cpu(current_task, cpu) = idle;
irq_ctx_init(cpu);
#else
- cpu_pda(cpu)->pcurrent = idle;
+ per_cpu(pda, cpu).pcurrent = idle;
clear_tsk_thread_flag(idle, TIF_FORK);
#endif
xen_setup_timer(cpu);
--
1.6.1.rc1


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