diff options
Diffstat (limited to 'arch/x86/lguest/i386_head.S')
| -rw-r--r-- | arch/x86/lguest/i386_head.S | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S index 4f420c2f2d55..e7d5382ef263 100644 --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -4,6 +4,7 @@ #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/processor-flags.h> +#include <asm/pgtable.h> /*G:020 * Our story starts with the kernel booting into startup_32 in @@ -37,9 +38,113 @@ ENTRY(lguest_entry) /* Set up the initial stack so we can run C code. */ movl $(init_thread_union+THREAD_SIZE),%esp + call init_pagetables + /* Jumps are relative: we're running __PAGE_OFFSET too low. */ jmp lguest_init+__PAGE_OFFSET +/* + * Initialize page tables. This creates a PDE and a set of page + * tables, which are located immediately beyond __brk_base. The variable + * _brk_end is set up to point to the first "safe" location. + * Mappings are created both at virtual address 0 (identity mapping) + * and PAGE_OFFSET for up to _end. + * + * FIXME: This code is taken verbatim from arch/x86/kernel/head_32.S: they + * don't have a stack at this point, so we can't just use call and ret. + */ +init_pagetables: +#if PTRS_PER_PMD > 1 +#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD) +#else +#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD) +#endif +#define pa(X) ((X) - __PAGE_OFFSET) + +/* Enough space to fit pagetables for the low memory linear map */ +MAPPING_BEYOND_END = \ + PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT +#ifdef CONFIG_X86_PAE + + /* + * In PAE mode initial_page_table is statically defined to contain + * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3 + * entries). The identity mapping is handled by pointing two PGD entries + * to the first kernel PMD. + * + * Note the upper half of each PMD or PTE are always zero at this stage. + */ + +#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ + + xorl %ebx,%ebx /* %ebx is kept at zero */ + + movl $pa(__brk_base), %edi + movl $pa(initial_pg_pmd), %edx + movl $PTE_IDENT_ATTR, %eax +10: + leal PDE_IDENT_ATTR(%edi),%ecx /* Create PMD entry */ + movl %ecx,(%edx) /* Store PMD entry */ + /* Upper half already zero */ + addl $8,%edx + movl $512,%ecx +11: + stosl + xchgl %eax,%ebx + stosl + xchgl %eax,%ebx + addl $0x1000,%eax + loop 11b + + /* + * End condition: we must map up to the end + MAPPING_BEYOND_END. + */ + movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp + cmpl %ebp,%eax + jb 10b +1: + addl $__PAGE_OFFSET, %edi + movl %edi, pa(_brk_end) + shrl $12, %eax + movl %eax, pa(max_pfn_mapped) + + /* Do early initialization of the fixmap area */ + movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax + movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) +#else /* Not PAE */ + +page_pde_offset = (__PAGE_OFFSET >> 20); + + movl $pa(__brk_base), %edi + movl $pa(initial_page_table), %edx + movl $PTE_IDENT_ATTR, %eax +10: + leal PDE_IDENT_ATTR(%edi),%ecx /* Create PDE entry */ + movl %ecx,(%edx) /* Store identity PDE entry */ + movl %ecx,page_pde_offset(%edx) /* Store kernel PDE entry */ + addl $4,%edx + movl $1024, %ecx +11: + stosl + addl $0x1000,%eax + loop 11b + /* + * End condition: we must map up to the end + MAPPING_BEYOND_END. + */ + movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp + cmpl %ebp,%eax + jb 10b + addl $__PAGE_OFFSET, %edi + movl %edi, pa(_brk_end) + shrl $12, %eax + movl %eax, pa(max_pfn_mapped) + + /* Do early initialization of the fixmap area */ + movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax + movl %eax,pa(initial_page_table+0xffc) +#endif + ret + /*G:055 * We create a macro which puts the assembler code between lgstart_ and lgend_ * markers. These templates are put in the .text section: they can't be |