Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c090f532 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by H. Peter Anvin
Browse files

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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 2bd2753f

arch/x86/kernel/head_32.S

+19 −10
Original line number Diff line number Diff line
@@ -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