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Commit 8bcf2c48 authored by Noam Camus's avatar Noam Camus Committed by Vineet Gupta
Browse files

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: default avatarNoam Camus <noamc@ezchip.com>
Acked-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 4a66d3fe

arch/arc/include/asm/processor.h

+18 −0
Original line number Diff line number Diff line
@@ -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

arch/arc/mm/tlb.c

+6 −0
Original line number Diff line number Diff line
@@ -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