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powerpc/64s: Relax PACA address limitations

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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: Nicholas Piggin <npiggin@gmail.com>
[mpe: Change mmu_has_feature() to early_mmu_has_feature()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2017-12-22 21:17:13 +10:00
committed by Michael Ellerman
parent c610d65c0a
commit 1af19331a3
3 changed files with 27 additions and 16 deletions
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13
arch/powerpc/kernel/paca.c
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@@ -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);