Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fc53b420 authored by Matt Evans's avatar Matt Evans Committed by Benjamin Herrenschmidt
Browse files

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: default avatarMatt Evans <matt@ozlabs.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 7e3f36c3

arch/powerpc/include/asm/paca.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/machine_kexec_64.c

+20 −0
Original line number Diff line number Diff line
@@ -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.

	 */

arch/powerpc/kernel/paca.c

+10 −0
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/kernel/setup_64.c

+0 −10
Original line number Diff line number Diff line
@@ -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