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powerpc/kexec: Switch to a static PACA on the way out

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With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
static data and there is a chance that something may stomp it when preparing
to kexec.  This patch switches this final CPU to a static PACA just before
we pull the switch.

Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Matt Evans
2010-07-07 21:55:37 +00:00
committed by Benjamin Herrenschmidt
parent 7e3f36c3e1
commit fc53b4202e
4 changed files with 31 additions and 11 deletions
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20
arch/powerpc/kernel/machine_kexec_64.c
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@ -260,6 +260,12 @@ static void kexec_prepare_cpus(void)
static union thread_union kexec_stack __init_task_data =
{ };
/*
* For similar reasons to the stack above, the kexecing CPU needs to be on a
* static PACA; we switch to kexec_paca.
*/
struct paca_struct kexec_paca;
/* Our assembly helper, in kexec_stub.S */
extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
void *image, void *control,
@ -287,6 +293,20 @@ void default_machine_kexec(struct kimage *image)
kexec_stack.thread_info.task = current_thread_info()->task;
kexec_stack.thread_info.flags = 0;
/* We need a static PACA, too; copy this CPU's PACA over and switch to
* it. Also poison per_cpu_offset to catch anyone using non-static
* data.
*/
memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
kexec_paca.paca_index;
setup_paca(&kexec_paca);
/* XXX: If anyone does 'dynamic lppacas' this will also need to be
* switched to a static version!
*/
/* Some things are best done in assembly. Finding globals with
* a toc is easier in C, so pass in what we can.
*/