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powerpc: Rename slb0_limit() to safe_stack_limit() and add Book3E support
slb0_limit() wasn't a very descriptive name. This changes it along with a comment explaining what it's used for, and provides a 64-bit BookE implementation. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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2 changed files with 22 additions and 5 deletions
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@ -245,6 +245,10 @@ extern struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
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extern int mmu_linear_psize;
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extern int mmu_vmemmap_psize;
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#ifdef CONFIG_PPC64
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extern unsigned long linear_map_top;
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#endif
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_POWERPC_MMU_BOOK3E_H_ */
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@ -434,17 +434,30 @@ void __init setup_system(void)
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DBG(" <- setup_system()\n");
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}
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static u64 slb0_limit(void)
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/* This returns the limit below which memory accesses to the linear
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* mapping are guarnateed not to cause a TLB or SLB miss. This is
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* used to allocate interrupt or emergency stacks for which our
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* exception entry path doesn't deal with being interrupted.
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*/
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static u64 safe_stack_limit(void)
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{
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if (mmu_has_feature(MMU_FTR_1T_SEGMENT)) {
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#ifdef CONFIG_PPC_BOOK3E
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/* Freescale BookE bolts the entire linear mapping */
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if (mmu_has_feature(MMU_FTR_TYPE_FSL_E))
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return linear_map_top;
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/* Other BookE, we assume the first GB is bolted */
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return 1ul << 30;
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#else
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/* BookS, the first segment is bolted */
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if (mmu_has_feature(MMU_FTR_1T_SEGMENT))
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return 1UL << SID_SHIFT_1T;
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}
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return 1UL << SID_SHIFT;
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#endif
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}
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static void __init irqstack_early_init(void)
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{
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u64 limit = slb0_limit();
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u64 limit = safe_stack_limit();
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unsigned int i;
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/*
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@ -497,7 +510,7 @@ static void __init emergency_stack_init(void)
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* bringup, we need to get at them in real mode. This means they
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* must also be within the RMO region.
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*/
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limit = min(slb0_limit(), ppc64_rma_size);
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limit = min(safe_stack_limit(), ppc64_rma_size);
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for_each_possible_cpu(i) {
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unsigned long sp;
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