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ARC: [plat-eznps] Use dedicated user stack top

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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 <noamc@ezchip.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Noam Camus 2015-12-06 15:40:55 +02:00 committed by Vineet Gupta
parent 4a66d3fecf
commit 8bcf2c48f3
2 changed files with 24 additions and 0 deletions
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18
arch/arc/include/asm/processor.h
View file

@ -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

6
arch/arc/mm/tlb.c
View file

@ -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