From b5ddb6d54729d814356937572d6c9b599f10c29f Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Thu, 3 Aug 2017 17:45:44 +0530 Subject: [PATCH] ARCv2: PAE40: set MSB even if !CONFIG_ARC_HAS_PAE40 but PAE exists in SoC PAE40 confiuration in hardware extends some of the address registers for TLB/cache ops to 2 words. So far kernel was NOT setting the higher word if feature was not enabled in software which is wrong. Those need to be set to 0 in such case. Normally this would be done in the cache flush / tlb ops, however since these registers only exist conditionally, this would have to be conditional to a flag being set on boot which is expensive/ugly - specially for the more common case of PAE exists but not in use. Optimize that by zero'ing them once at boot - nobody will write to them afterwards Cc: stable@vger.kernel.org #4.4+ Signed-off-by: Vineet Gupta --- arch/arc/include/asm/mmu.h | 2 ++ arch/arc/mm/cache.c | 34 ++++++++++++++++++++++++++++------ arch/arc/mm/tlb.c | 12 +++++++++++- 3 files changed, 41 insertions(+), 7 deletions(-) diff --git a/arch/arc/include/asm/mmu.h b/arch/arc/include/asm/mmu.h index db7319e9b506..efb79fafff1d 100644 --- a/arch/arc/include/asm/mmu.h +++ b/arch/arc/include/asm/mmu.h @@ -94,6 +94,8 @@ static inline int is_pae40_enabled(void) return IS_ENABLED(CONFIG_ARC_HAS_PAE40); } +extern int pae40_exist_but_not_enab(void); + #endif /* !__ASSEMBLY__ */ #endif diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c index 874913b3e826..7db283b46ebd 100644 --- a/arch/arc/mm/cache.c +++ b/arch/arc/mm/cache.c @@ -1123,6 +1123,13 @@ noinline void __init arc_ioc_setup(void) __dc_enable(); } +/* + * Cache related boot time checks/setups only needed on master CPU: + * - Geometry checks (kernel build and hardware agree: e.g. L1_CACHE_BYTES) + * Assume SMP only, so all cores will have same cache config. A check on + * one core suffices for all + * - IOC setup / dma callbacks only need to be done once + */ void __init arc_cache_init_master(void) { unsigned int __maybe_unused cpu = smp_processor_id(); @@ -1202,12 +1209,27 @@ void __ref arc_cache_init(void) printk(arc_cache_mumbojumbo(0, str, sizeof(str))); - /* - * Only master CPU needs to execute rest of function: - * - Assume SMP so all cores will have same cache config so - * any geomtry checks will be same for all - * - IOC setup / dma callbacks only need to be setup once - */ if (!cpu) arc_cache_init_master(); + + /* + * In PAE regime, TLB and cache maintenance ops take wider addresses + * And even if PAE is not enabled in kernel, the upper 32-bits still need + * to be zeroed to keep the ops sane. + * As an optimization for more common !PAE enabled case, zero them out + * once at init, rather than checking/setting to 0 for every runtime op + */ + if (is_isa_arcv2() && pae40_exist_but_not_enab()) { + + if (IS_ENABLED(CONFIG_ARC_HAS_ICACHE)) + write_aux_reg(ARC_REG_IC_PTAG_HI, 0); + + if (IS_ENABLED(CONFIG_ARC_HAS_DCACHE)) + write_aux_reg(ARC_REG_DC_PTAG_HI, 0); + + if (l2_line_sz) { + write_aux_reg(ARC_REG_SLC_RGN_END1, 0); + write_aux_reg(ARC_REG_SLC_RGN_START1, 0); + } + } } diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c index d0126fdfe2d8..b181f3ee38aa 100644 --- a/arch/arc/mm/tlb.c +++ b/arch/arc/mm/tlb.c @@ -104,6 +104,8 @@ /* A copy of the ASID from the PID reg is kept in asid_cache */ DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE; +static int __read_mostly pae_exists; + /* * Utility Routine to erase a J-TLB entry * Caller needs to setup Index Reg (manually or via getIndex) @@ -784,7 +786,7 @@ void read_decode_mmu_bcr(void) mmu->u_dtlb = mmu4->u_dtlb * 4; mmu->u_itlb = mmu4->u_itlb * 4; mmu->sasid = mmu4->sasid; - mmu->pae = mmu4->pae; + pae_exists = mmu->pae = mmu4->pae; } } @@ -809,6 +811,11 @@ char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len) return buf; } +int pae40_exist_but_not_enab(void) +{ + return pae_exists && !is_pae40_enabled(); +} + void arc_mmu_init(void) { char str[256]; @@ -859,6 +866,9 @@ void arc_mmu_init(void) /* swapper_pg_dir is the pgd for the kernel, used by vmalloc */ write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir); #endif + + if (pae40_exist_but_not_enab()) + write_aux_reg(ARC_REG_TLBPD1HI, 0); } /* -- 2.30.2