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authorNoam Camus <noamc@ezchip.com>2015-12-06 15:40:55 +0200
committerVineet Gupta <vgupta@synopsys.com>2016-05-09 09:32:32 +0530
commit8bcf2c48f32e22f923b69f779c95b1348308d5b1 (patch)
treede985a3469686b3dfc5cb59c2c180c5ba53e6e44 /arch/arc
parent4a66d3fecf6554c4e1482774833da4f07cade787 (diff)
downloadlinux-8bcf2c48f32e22f923b69f779c95b1348308d5b1.tar.bz2
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 <noamc@ezchip.com> Acked-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/include/asm/processor.h18
-rw-r--r--arch/arc/mm/tlb.c6
2 files changed, 24 insertions, 0 deletions
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