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

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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2
arch/powerpc/include/asm/paca.h
View File

@ -146,7 +146,7 @@ struct paca_struct {
extern struct paca_struct *paca;
extern __initdata struct paca_struct boot_paca;
extern void initialise_paca(struct paca_struct *new_paca, int cpu);
extern void setup_paca(struct paca_struct *new_paca);
extern void allocate_pacas(void);
extern void free_unused_pacas(void);

20
arch/powerpc/kernel/machine_kexec_64.c
View File

@ -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.
*/

10
arch/powerpc/kernel/paca.c
View File

@ -105,6 +105,16 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu)
#endif /* CONFIG_PPC_STD_MMU_64 */
}
/* Put the paca pointer into r13 and SPRG_PACA */
void setup_paca(struct paca_struct *new_paca)
{
local_paca = new_paca;
mtspr(SPRN_SPRG_PACA, local_paca);
#ifdef CONFIG_PPC_BOOK3E
mtspr(SPRN_SPRG_TLB_EXFRAME, local_paca->extlb);
#endif
}
static int __initdata paca_size;
void __init allocate_pacas(void)

10
arch/powerpc/kernel/setup_64.c
View File

@ -142,16 +142,6 @@ early_param("smt-enabled", early_smt_enabled);
#define check_smt_enabled()
#endif /* CONFIG_SMP */
/* Put the paca pointer into r13 and SPRG_PACA */
static void __init setup_paca(struct paca_struct *new_paca)
{
local_paca = new_paca;
mtspr(SPRN_SPRG_PACA, local_paca);
#ifdef CONFIG_PPC_BOOK3E
mtspr(SPRN_SPRG_TLB_EXFRAME, local_paca->extlb);
#endif
}
/*
* Early initialization entry point. This is called by head.S
* with MMU translation disabled. We rely on the "feature" of