From 8bcf2c48f32e22f923b69f779c95b1348308d5b1 Mon Sep 17 00:00:00 2001 From: Noam Camus Date: Sun, 6 Dec 2015 15:40:55 +0200 Subject: [PATCH] ARC: [plat-eznps] Use dedicated user stack top NPS use special mapping right below TASK_SIZE. Hence we need to lower STACK_TOP so that user stack won't overlap NPS special mapping. Signed-off-by: Noam Camus Acked-by: Vineet Gupta --- arch/arc/include/asm/processor.h | 18 ++++++++++++++++++ arch/arc/mm/tlb.c | 6 ++++++ 2 files changed, 24 insertions(+) diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h index d0a9211ec769..194a09fce198 100644 --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.h @@ -121,7 +121,25 @@ extern unsigned int get_wchan(struct task_struct *p); #define USER_KERNEL_GUTTER (VMALLOC_START - TASK_SIZE) +#ifdef CONFIG_ARC_PLAT_EZNPS +/* NPS architecture defines special window of 129M in user address space for + * special memory areas, when accessing this window the MMU do not use TLB. + * Instead MMU direct the access to: + * 0x57f00000:0x57ffffff -- 1M of closely coupled memory (aka CMEM) + * 0x58000000:0x5fffffff -- 16 huge pages, 8M each, with fixed map (aka FMTs) + * + * CMEM - is the fastest memory we got and its size is 16K. + * FMT - is used to map either to internal/external memory. + * Internal memory is the second fast memory and its size is 16M + * External memory is the biggest memory (16G) and also the slowest. + * + * STACK_TOP need to be PMD align (21bit) that is why we supply 0x57e00000. + */ +#define STACK_TOP 0x57e00000 +#else #define STACK_TOP TASK_SIZE +#endif + #define STACK_TOP_MAX STACK_TOP /* This decides where the kernel will search for a free chunk of vm diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c index 745a9aeb2d96..ec868a9081a1 100644 --- a/arch/arc/mm/tlb.c +++ b/arch/arc/mm/tlb.c @@ -819,6 +819,12 @@ void arc_mmu_init(void) */ BUILD_BUG_ON(!IS_ALIGNED((CONFIG_ARC_KVADDR_SIZE << 20), PMD_SIZE)); + /* + * stack top size sanity check, + * Can't be done in processor.h due to header include depenedencies + */ + BUILD_BUG_ON(!IS_ALIGNED(STACK_TOP, PMD_SIZE)); + /* For efficiency sake, kernel is compile time built for a MMU ver * This must match the hardware it is running on. * Linux built for MMU V2, if run on MMU V1 will break down because V1 -- 2.20.1