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Commit 1af19331 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/64s: Relax PACA address limitations 



Book3S PACA memory allocation is restricted by the RMA limit and also
must not take SLB faults when accessed in virtual mode. Currently a
fixed 256MB limit is used for this, which is imprecise and sub-optimal.

Update the paca allocation limits to use use the ppc64_rma_size for RMA
limit, and share the safe_stack_limit() that is currently used for stack
allocations that must not take virtual mode faults.

The safe_stack_limit() name is changed to ppc64_bolted_size() to match
ppc64_rma_size and some comments are updated. We also need to use
early_mmu_has_feature() because we are now calling this function prior
to the jump label patching that enables mmu_has_feature().

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
[mpe: Change mmu_has_feature() to early_mmu_has_feature()]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c610d65c

arch/powerpc/kernel/paca.c

+7 −6
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include <asm/pgtable.h>

#include <asm/kexec.h>



#include "setup.h"



#ifdef CONFIG_PPC_BOOK3S



/*
@@ -208,15 +210,14 @@ void __init allocate_pacas(void) 
	u64 limit;

	int cpu;



	limit = ppc64_rma_size;



#ifdef CONFIG_PPC_BOOK3S_64

	/*

	 * We can't take SLB misses on the paca, and we want to access them

	 * in real mode, so allocate them within the RMA and also within

	 * the first segment.

	 * We access pacas in real mode, and cannot take SLB faults

	 * on them when in virtual mode, so allocate them accordingly.

	 */

	limit = min(0x10000000ULL, limit);

	limit = min(ppc64_bolted_size(), ppc64_rma_size);

#else

	limit = ppc64_rma_size;

#endif



	paca_size = PAGE_ALIGN(sizeof(struct paca_struct) * nr_cpu_ids);

arch/powerpc/kernel/setup.h

+4 −0
Original line number Diff line number Diff line
@@ -51,6 +51,10 @@ void record_spr_defaults(void); 
static inline void record_spr_defaults(void) { };

#endif



#ifdef CONFIG_PPC64

u64 ppc64_bolted_size(void);

#endif



/*

 * Having this in kvm_ppc.h makes include dependencies too

 * tricky to solve for setup-common.c so have it here.

arch/powerpc/kernel/setup_64.c

+16 −10
Original line number Diff line number Diff line
@@ -565,25 +565,31 @@ void __init initialize_cache_info(void) 
	DBG(" <- initialize_cache_info()\n");

}



/* This returns the limit below which memory accesses to the linear

 * mapping are guarnateed not to cause a TLB or SLB miss. This is

 * used to allocate interrupt or emergency stacks for which our

 * exception entry path doesn't deal with being interrupted.

/*

 * This returns the limit below which memory accesses to the linear

 * mapping are guarnateed not to cause an architectural exception (e.g.,

 * TLB or SLB miss fault).

 *

 * This is used to allocate PACAs and various interrupt stacks that

 * that are accessed early in interrupt handlers that must not cause

 * re-entrant interrupts.

 */

static __init u64 safe_stack_limit(void)

__init u64 ppc64_bolted_size(void)

{

#ifdef CONFIG_PPC_BOOK3E

	/* Freescale BookE bolts the entire linear mapping */

	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E))

	/* XXX: BookE ppc64_rma_limit setup seems to disagree? */

	if (early_mmu_has_feature(MMU_FTR_TYPE_FSL_E))

		return linear_map_top;

	/* Other BookE, we assume the first GB is bolted */

	return 1ul << 30;

#else

	/* BookS radix, does not take faults on linear mapping */

	if (early_radix_enabled())

		return ULONG_MAX;



	/* BookS, the first segment is bolted */

	if (mmu_has_feature(MMU_FTR_1T_SEGMENT))

	/* BookS hash, the first segment is bolted */

	if (early_mmu_has_feature(MMU_FTR_1T_SEGMENT))

		return 1UL << SID_SHIFT_1T;

	return 1UL << SID_SHIFT;

#endif
@@ -591,7 +597,7 @@ static __init u64 safe_stack_limit(void) 


void __init irqstack_early_init(void)

{

	u64 limit = safe_stack_limit();

	u64 limit = ppc64_bolted_size();

	unsigned int i;



	/*
@@ -676,7 +682,7 @@ void __init emergency_stack_init(void) 
	 * initialized in kernel/irq.c. These are initialized here in order

	 * to have emergency stacks available as early as possible.

	 */

	limit = min(safe_stack_limit(), ppc64_rma_size);

	limit = min(ppc64_bolted_size(), ppc64_rma_size);



	for_each_possible_cpu(i) {

		struct thread_info *ti;