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ARC: mm: document system mem map clearly 

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2015-03-05 14:46:20 +05:30
parent def32fad84
commit 4db27dca60
2 changed files with 17 additions and 20 deletions
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35
arch/arc/include/asm/processor.h
View File

@ -100,29 +100,26 @@ extern unsigned int get_wchan(struct task_struct *p);
#endif /* !__ASSEMBLY__ */
/* Kernels Virtual memory area.
* Unlike other architectures(MIPS, sh, cris ) ARC 700 does not have a
* "kernel translated" region (like KSEG2 in MIPS). So we use a upper part
* of the translated bottom 2GB for kernel virtual memory and protect
* these pages from user accesses by disabling Ru, Eu and Wu.
/*
* System Memory Map on ARC
*
* ---------------------------- (lower 2G, Translated) -------------------------
* 0x0000_0000 0x5FFF_FFFF (user vaddr: TASK_SIZE)
* 0x6000_0000 0x6FFF_FFFF (reserved gutter between U/K)
* 0x7000_0000 0x7FFF_FFFF (kvaddr: vmalloc/modules/pkmap..)
*
* PAGE_OFFSET ---------------- (Upper 2G, Untranslated) -----------------------
* 0x8000_0000 0xBFFF_FFFF (kernel direct mapped)
* 0xC000_0000 0xFFFF_FFFF (peripheral uncached space)
* -----------------------------------------------------------------------------
*/
#define VMALLOC_SIZE (0x10000000) /* 256M */
#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
#define VMALLOC_END (PAGE_OFFSET)
#define VMALLOC_START 0x70000000
#define VMALLOC_SIZE (PAGE_OFFSET - VMALLOC_START)
#define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE)
/* Most of the architectures seem to be keeping some kind of padding between
* userspace TASK_SIZE and PAGE_OFFSET. i.e TASK_SIZE != PAGE_OFFSET.
*/
#define USER_KERNEL_GUTTER 0x10000000
/* User address space:
* On ARC700, CPU allows the entire lower half of 32 bit address space to be
* translated. Thus potentially 2G (0:0x7FFF_FFFF) could be User vaddr space.
* However we steal 256M for kernel addr (0x7000_0000:0x7FFF_FFFF) and another
* 256M (0x6000_0000:0x6FFF_FFFF) is gutter between user/kernel spaces
* Thus total User vaddr space is (0:0x5FFF_FFFF)
*/
#define TASK_SIZE (PAGE_OFFSET - VMALLOC_SIZE - USER_KERNEL_GUTTER)
#define TASK_SIZE (VMALLOC_START - USER_KERNEL_GUTTER)
#define STACK_TOP TASK_SIZE
#define STACK_TOP_MAX STACK_TOP

2
arch/arc/include/uapi/asm/page.h
View File

@ -30,7 +30,7 @@
#define PAGE_OFFSET (0x80000000)
#else
#define PAGE_SIZE (1UL << PAGE_SHIFT) /* Default 8K */
#define PAGE_OFFSET (0x80000000UL) /* Kernel starts at 2G onwards */
#define PAGE_OFFSET (0x80000000UL) /* Kernel starts at 2G onwards */
#endif
#define PAGE_MASK (~(PAGE_SIZE-1))