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Subject[PATCH] x86: fix init_memory_mapping for [dc000000 - e0000000)

Impact: fix range calculation

when gart aperture is 0xdc000000 - 0xe0000000
it returned 0xc0000000 - 0xe0000000

PCI-DMA: Disabling AGP.
PCI-DMA: aperture base @ dc000000 size 65536 KB
init_memory_mapping
00c0000000 - 00e0000000 page 2M
last_map_addr: e0000000 end: e0000000
PCI-DMA: using GART IOMMU.
PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture

that is not right.

this patch fix that will get exact mapping

on 256g sytem with that aperture after patch
LBSuse:~ # cat /proc/meminfo
MemTotal: 264742432 kB
MemFree: 263920628 kB
Buffers: 1416 kB
Cached: 24468 kB
...
DirectMap4k: 5760 kB
DirectMap2M: 3205120 kB
DirectMap1G: 265289728 kB

it is consistent to
LBSuse:~ # cat /sys/kernel/debug/kernel_page_tables
..
---[ Low Kernel Mapping ]---
0xffff880000000000-0xffff880000200000 2M RW GLB x pte
0xffff880000200000-0xffff880040000000 1022M RW PSE GLB x pmd
0xffff880040000000-0xffff8800c0000000 2G RW PSE GLB NX pud
0xffff8800c0000000-0xffff8800d7e00000 382M RW PSE GLB NX pmd
0xffff8800d7e00000-0xffff8800d7fa0000 1664K RW GLB NX pte
0xffff8800d7fa0000-0xffff8800d8000000 384K pte
0xffff8800d8000000-0xffff8800dc000000 64M pmd
0xffff8800dc000000-0xffff8800e0000000 64M RW PSE GLB NX pmd
0xffff8800e0000000-0xffff880100000000 512M pmd
0xffff880100000000-0xffff880800000000 28G RW PSE GLB NX pud
0xffff880800000000-0xffff880824600000 582M RW PSE GLB NX pmd
0xffff880824600000-0xffff8808247f0000 1984K RW GLB NX pte
0xffff8808247f0000-0xffff880824800000 64K RW PCD GLB NX pte
0xffff880824800000-0xffff880840000000 440M RW PSE GLB NX pmd
0xffff880840000000-0xffff884000000000 223G RW PSE GLB NX pud
0xffff884000000000-0xffff884028000000 640M RW PSE GLB NX pmd
0xffff884028000000-0xffff884040000000 384M pmd
0xffff884040000000-0xffff888000000000 255G pud
0xffff888000000000-0xffffc20000000000 58880G pgd

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
arch/x86/mm/init_64.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -676,7 +676,7 @@ unsigned long __init_refok init_memory_m
int nr_range, i;
int use_pse, use_gbpages;

- printk(KERN_INFO "init_memory_mapping\n");
+ printk(KERN_INFO "init_memory_mapping: %016lx-%016lx\n", start, end);

/*
* Find space for the kernel direct mapping tables.
@@ -719,26 +719,30 @@ unsigned long __init_refok init_memory_m
<< (PMD_SHIFT - PAGE_SHIFT);
end_pfn = ((start + (PUD_SIZE - 1))>>PUD_SHIFT)
<< (PUD_SHIFT - PAGE_SHIFT);
- if (end_pfn > ((end>>PUD_SHIFT)<<(PUD_SHIFT - PAGE_SHIFT)))
- end_pfn = ((end>>PUD_SHIFT)<<(PUD_SHIFT - PAGE_SHIFT));
+ if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
+ end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
page_size_mask & (1<<PG_LEVEL_2M));

/* big page (1G) range */
- start_pfn = end_pfn;
+ start_pfn = ((start + (PUD_SIZE - 1))>>PUD_SHIFT)
+ << (PUD_SHIFT - PAGE_SHIFT);
end_pfn = (end>>PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
- nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
+ if (start_pfn < end_pfn) {
+ /* if no 1g blocks, no 2M blocks on tail*/
+ nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
page_size_mask &
((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));

- /* tail is not big page (1G) alignment */
- start_pfn = end_pfn;
- end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
- nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
- page_size_mask & (1<<PG_LEVEL_2M));
+ /* tail is not big page (1G) alignment */
+ start_pfn = end_pfn;
+ end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
+ nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
+ page_size_mask & (1<<PG_LEVEL_2M));
+ }

/* tail is not big page (2M) alignment */
- start_pfn = end_pfn;
+ start_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
end_pfn = end>>PAGE_SHIFT;
nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);


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