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| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-03-16 20:07:54 +0100 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2009-03-17 19:42:05 +0100 |
| commit | c090f532db3ab5b7be503f8ac84b0d33a18646c6 (patch) | |
| tree | abac222a32abc03730ccfa260d28af88581f6fb6 /arch/x86/kernel/head_32.S | |
| parent | x86: put initial_pg_tables into .bss (diff) | |
| download | linux-c090f532db3ab5b7be503f8ac84b0d33a18646c6.tar.xz linux-c090f532db3ab5b7be503f8ac84b0d33a18646c6.zip | |
x86-32: make sure we map enough to fit linear map pagetables
Impact: crash fix
head_32.S needs to map the kernel itself, and enough space so
that mm/init.c can allocate space from the e820 allocator
for the linear map of low memory.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/head_32.S')
| -rw-r--r-- | arch/x86/kernel/head_32.S | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index c79741cfb078..d383a7c0e49f 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -38,8 +38,8 @@ #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id /* - * This is how much memory *in addition to the memory covered up to - * and including _end* we need mapped initially. + * This is how much memory in addition to the memory covered up to + * and including _end we need mapped initially. * We need: * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE) * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE) @@ -52,16 +52,25 @@ * KERNEL_IMAGE_SIZE should be greater than pa(_end) * and small than max_low_pfn, otherwise will waste some page table entries */ -LOW_PAGES = (KERNEL_IMAGE_SIZE + PAGE_SIZE_asm - 1)>>PAGE_SHIFT #if PTRS_PER_PMD > 1 -PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PMD) + PTRS_PER_PGD +#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD) #else -PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PGD) +#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD) #endif ALLOCATOR_SLOP = 4 -INIT_MAP_SIZE = (PAGE_TABLE_SIZE + ALLOCATOR_SLOP) * PAGE_SIZE_asm +/* Enough space to fit pagetables for the low memory linear map */ +MAPPING_BEYOND_END = (PAGE_TABLE_SIZE(1 << (32 - PAGE_SHIFT)) * PAGE_SIZE) + +/* + * Worst-case size of the kernel mapping we need to make: + * the worst-case size of the kernel itself, plus the extra we need + * to map for the linear map. + */ +KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT + +INIT_MAP_SIZE = (PAGE_TABLE_SIZE(KERNEL_PAGES) + ALLOCATOR_SLOP) * PAGE_SIZE_asm RESERVE_BRK(pagetables, INIT_MAP_SIZE) /* @@ -197,9 +206,9 @@ default_entry: loop 11b /* - * End condition: we must map up to the end. + * End condition: we must map up to the end + MAPPING_BEYOND_END. */ - movl $pa(_end) + PTE_IDENT_ATTR, %ebp + movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b 1: @@ -229,9 +238,9 @@ page_pde_offset = (__PAGE_OFFSET >> 20); addl $0x1000,%eax loop 11b /* - * End condition: we must map up to end + * End condition: we must map up to the end + MAPPING_BEYOND_END. */ - movl $pa(_end) + PTE_IDENT_ATTR, %ebp + movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b addl $__PAGE_OFFSET, %edi |