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x86: fold pda into percpu area on SMP

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[ Based on original patch from Christoph Lameter and Mike Travis. ]

Currently pdas and percpu areas are allocated separately.  %gs points
to local pda and percpu area can be reached using pda->data_offset.
This patch folds pda into percpu area.

Due to strange gcc requirement, pda needs to be at the beginning of
the percpu area so that pda->stack_canary is at %gs:40.  To achieve
this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is
added and used to reserve pda sized chunk at the start of the percpu
area.

After this change, for boot cpu, %gs first points to pda in the
data.init area and later during setup_per_cpu_areas() gets updated to
point to the actual pda.  This means that setup_per_cpu_areas() need
to reload %gs for CPU0 while clearing pda area for other cpus as cpu0
already has modified it when control reaches setup_per_cpu_areas().

This patch also removes now unnecessary get_local_pda() and its call
sites.

A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into
per cpu area" patch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Tejun Heo
2009-01-13 20:41:35 +09:00
committed by Ingo Molnar
parent c8f3329a0d
commit 1a51e3a0ae
11 changed files with 104 additions and 144 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
arch/x86/kernel/smpboot.c
View File

@@ -744,52 +744,6 @@ 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
@@ -807,16 +761,6 @@ 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);
@@ -931,9 +875,7 @@ do_rest:
inquire_remote_apic(apicid);
}
}
#ifdef CONFIG_X86_64
restore_state:
#endif
if (boot_error) {
/* Try to put things back the way they were before ... */
numa_remove_cpu(cpu); /* was set by numa_add_cpu */