path: root/include/asm-powerpc
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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-05-08 16:27:27 +1000
committerPaul Mackerras <paulus@samba.org>2007-05-09 16:35:00 +1000
commitd0f13e3c20b6fb73ccb467bdca97fa7cf5a574cd (patch)
treea2de01a21dbb28449893102742e6b516a519c03e /include/asm-powerpc
parent16f1c746755836aa823658000493cdab8ce7b098 (diff)
[POWERPC] Introduce address space "slices"
The basic issue is to be able to do what hugetlbfs does but with different page sizes for some other special filesystems; more specifically, my need is: - Huge pages - SPE local store mappings using 64K pages on a 4K base page size kernel on Cell - Some special 4K segments in 64K-page kernels for mapping a dodgy type of powerpc-specific infiniband hardware that requires 4K MMU mappings for various reasons I won't explain here. The main issues are: - To maintain/keep track of the page size per "segment" (as we can only have one page size per segment on powerpc, which are 256MB divisions of the address space). - To make sure special mappings stay within their allotted "segments" (including MAP_FIXED crap) - To make sure everybody else doesn't mmap/brk/grow_stack into a "segment" that is used for a special mapping Some of the necessary mechanisms to handle that were present in the hugetlbfs code, but mostly in ways not suitable for anything else. The patch relies on some changes to the generic get_unmapped_area() that just got merged. It still hijacks hugetlb callbacks here or there as the generic code hasn't been entirely cleaned up yet but that shouldn't be a problem. So what is a slice ? Well, I re-used the mechanism used formerly by our hugetlbfs implementation which divides the address space in "meta-segments" which I called "slices". The division is done using 256MB slices below 4G, and 1T slices above. Thus the address space is divided currently into 16 "low" slices and 16 "high" slices. (Special case: high slice 0 is the area between 4G and 1T). Doing so simplifies significantly the tracking of segments and avoids having to keep track of all the 256MB segments in the address space. While I used the "concepts" of hugetlbfs, I mostly re-implemented everything in a more generic way and "ported" hugetlbfs to it. Slices can have an associated page size, which is encoded in the mmu context and used by the SLB miss handler to set the segment sizes. The hash code currently doesn't care, it has a specific check for hugepages, though I might add a mechanism to provide per-slice hash mapping functions in the future. The slice code provide a pair of "generic" get_unmapped_area() (bottomup and topdown) functions that should work with any slice size. There is some trickiness here so I would appreciate people to have a look at the implementation of these and let me know if I got something wrong. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'include/asm-powerpc')
3 files changed, 50 insertions, 49 deletions
diff --git a/include/asm-powerpc/mmu-hash64.h b/include/asm-powerpc/mmu-hash64.h
index 6739457d8bc..e2ca55bcfe0 100644
--- a/include/asm-powerpc/mmu-hash64.h
+++ b/include/asm-powerpc/mmu-hash64.h
@@ -350,10 +350,13 @@ typedef unsigned long mm_context_id_t;
typedef struct {
mm_context_id_t id;
- u16 user_psize; /* page size index */
- u16 sllp; /* SLB entry page size encoding */
- u16 low_htlb_areas, high_htlb_areas;
+ u16 user_psize; /* page size index */
+ u64 low_slices_psize; /* SLB page size encodings */
+ u64 high_slices_psize; /* 4 bits per slice for now */
+ u16 sllp; /* SLB page size encoding */
unsigned long vdso_base;
} mm_context_t;
diff --git a/include/asm-powerpc/paca.h b/include/asm-powerpc/paca.h
index cf95274f735..c6a5b173566 100644
--- a/include/asm-powerpc/paca.h
+++ b/include/asm-powerpc/paca.h
@@ -83,8 +83,8 @@ struct paca_struct {
mm_context_t context;
u16 vmalloc_sllp;
- u16 slb_cache[SLB_CACHE_ENTRIES];
u16 slb_cache_ptr;
+ u16 slb_cache[SLB_CACHE_ENTRIES];
* then miscellaneous read-write fields
diff --git a/include/asm-powerpc/page_64.h b/include/asm-powerpc/page_64.h
index eab779c2199..3448a3d4bc6 100644
--- a/include/asm-powerpc/page_64.h
+++ b/include/asm-powerpc/page_64.h
@@ -88,57 +88,55 @@ extern unsigned int HPAGE_SHIFT;
#endif /* __ASSEMBLY__ */
-#define HTLB_AREA_SHIFT 40
-#define GET_HTLB_AREA(x) ((x) >> HTLB_AREA_SHIFT)
+#define SLICE_LOW_SHIFT 28
+#define SLICE_HIGH_SHIFT 40
-#define LOW_ESID_MASK(addr, len) \
- (((1U << (GET_ESID(min((addr)+(len)-1, 0x100000000UL))+1)) \
- - (1U << GET_ESID(min((addr), 0x100000000UL)))) & 0xffff)
-#define HTLB_AREA_MASK(addr, len) (((1U << (GET_HTLB_AREA(addr+len-1)+1)) \
- - (1U << GET_HTLB_AREA(addr))) & 0xffff)
+#define SLICE_LOW_TOP (0x100000000ul)
+#define GET_LOW_SLICE_INDEX(addr) ((addr) >> SLICE_LOW_SHIFT)
+#define GET_HIGH_SLICE_INDEX(addr) ((addr) >> SLICE_HIGH_SHIFT)
-#define touches_hugepage_low_range(mm, addr, len) \
- (((addr) < 0x100000000UL) \
- && (LOW_ESID_MASK((addr), (len)) & (mm)->context.low_htlb_areas))
-#define touches_hugepage_high_range(mm, addr, len) \
- ((((addr) + (len)) > 0x100000000UL) \
- && (HTLB_AREA_MASK((addr), (len)) & (mm)->context.high_htlb_areas))
-#define __within_hugepage_low_range(addr, len, segmask) \
- ( (((addr)+(len)) <= 0x100000000UL) \
- && ((LOW_ESID_MASK((addr), (len)) | (segmask)) == (segmask)))
-#define within_hugepage_low_range(addr, len) \
- __within_hugepage_low_range((addr), (len), \
- current->mm->context.low_htlb_areas)
-#define __within_hugepage_high_range(addr, len, zonemask) \
- ( ((addr) >= 0x100000000UL) \
- && ((HTLB_AREA_MASK((addr), (len)) | (zonemask)) == (zonemask)))
-#define within_hugepage_high_range(addr, len) \
- __within_hugepage_high_range((addr), (len), \
- current->mm->context.high_htlb_areas)
-#define is_hugepage_only_range(mm, addr, len) \
- (touches_hugepage_high_range((mm), (addr), (len)) || \
- touches_hugepage_low_range((mm), (addr), (len)))
+#ifndef __ASSEMBLY__
+struct slice_mask {
+ u16 low_slices;
+ u16 high_slices;
+struct mm_struct;
-#define in_hugepage_area(context, addr) \
- (cpu_has_feature(CPU_FTR_16M_PAGE) && \
- ( ( (addr) >= 0x100000000UL) \
- ? ((1 << GET_HTLB_AREA(addr)) & (context).high_htlb_areas) \
- : ((1 << GET_ESID(addr)) & (context).low_htlb_areas) ) )
+extern unsigned long slice_get_unmapped_area(unsigned long addr,
+ unsigned long len,
+ unsigned long flags,
+ unsigned int psize,
+ int topdown,
+ int use_cache);
+extern unsigned int get_slice_psize(struct mm_struct *mm,
+ unsigned long addr);
-#define in_hugepage_area(mm, addr) 0
+extern void slice_init_context(struct mm_struct *mm, unsigned int psize);
+extern void slice_set_user_psize(struct mm_struct *mm, unsigned int psize);
+extern int is_hugepage_only_range(struct mm_struct *m,
+ unsigned long addr,
+ unsigned long len);
+#endif /* __ASSEMBLY__ */
+#define slice_init()
+#endif /* CONFIG_PPC_MM_SLICES */