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x86_64: add workaround for no %gs-based percpu

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As a stopgap until Mike Travis's x86-64 gs-based percpu patches are
ready, provide workaround functions for x86_read/write_percpu for
Xen's use.

Specifically, this means that we can't really make use of vcpu
placement, because we can't use a single gs-based memory access to get
to vcpu fields.  So disable all that for now.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge
2008-07-08 15:06:42 -07:00
committed by Ingo Molnar
parent a9e7062d73
commit 5b09b2876e
4 changed files with 40 additions and 3 deletions
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11
arch/x86/kernel/head64.c
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@ -39,6 +39,13 @@ static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata;
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);
@ -102,9 +109,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
early_printk("Kernel alive\n");
_cpu_pda = __cpu_pda;
cpu_pda(0) = &_boot_cpu_pda;
pda_init(0);
x86_64_init_pda();
early_printk("Kernel really alive\n");