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Commit 1e620f9b authored by Boris Ostrovsky's avatar Boris Ostrovsky Committed by Ingo Molnar
Browse files

x86/boot/32: Convert the 32-bit pgtable setup code from assembly to C 



The new Xen PVH entry point requires page tables to be setup by the
kernel since it is entered with paging disabled.

Pull the common code out of head_32.S so that mk_early_pgtbl_32() can be
invoked from both the new Xen entry point and the existing startup_32()
code.

Convert resulting common code to C.

Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: matt@codeblueprint.co.uk
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1481215471-9639-1-git-send-email-boris.ostrovsky@oracle.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b4ed1d15

arch/x86/include/asm/pgtable_32.h

+32 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ struct vm_area_struct; 


extern pgd_t swapper_pg_dir[1024];

extern pgd_t initial_page_table[1024];

extern pmd_t initial_pg_pmd[];



static inline void pgtable_cache_init(void) { }

static inline void check_pgt_cache(void) { }
@@ -75,4 +76,35 @@ do { \ 
#define kern_addr_valid(kaddr)	(0)

#endif



/*

 * 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)

 *

 * Modulo rounding, each megabyte assigned here requires a kilobyte of

 * memory, which is currently unreclaimed.

 *

 * This should be a multiple of a page.

 *

 * KERNEL_IMAGE_SIZE should be greater than pa(_end)

 * and small than max_low_pfn, otherwise will waste some page table entries

 */

#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



/*

 * Number of possible pages in the lowmem region.

 *

 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a

 * gas warning about overflowing shift count when gas has been compiled

 * with only a host target support using a 32-bit type for internal

 * representation.

 */

#define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))



#endif /* _ASM_X86_PGTABLE_32_H */

arch/x86/kernel/head32.c

+62 −0
Original line number Diff line number Diff line
@@ -49,3 +49,65 @@ asmlinkage __visible void __init i386_start_kernel(void) 


	start_kernel();

}



/*

 * 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.

 *

 * 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.

 */

void __init mk_early_pgtbl_32(void)

{

#ifdef __pa

#undef __pa

#endif

#define __pa(x)  ((unsigned long)(x) - PAGE_OFFSET)

	pte_t pte, *ptep;

	int i;

	unsigned long *ptr;

	/* Enough space to fit pagetables for the low memory linear map */

	const unsigned long limit = __pa(_end) +

		(PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);

#ifdef CONFIG_X86_PAE

	pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);

#define SET_PL2(pl2, val)    { (pl2).pmd = (val); }

#else

	pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);

#define SET_PL2(pl2, val)   { (pl2).pgd = (val); }

#endif



	ptep = (pte_t *)__pa(__brk_base);

	pte.pte = PTE_IDENT_ATTR;



	while ((pte.pte & PTE_PFN_MASK) < limit) {



		SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);

		*pl2p = pl2;

#ifndef CONFIG_X86_PAE

		/* Kernel PDE entry */

		*(pl2p +  ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;

#endif

		for (i = 0; i < PTRS_PER_PTE; i++) {

			*ptep = pte;

			pte.pte += PAGE_SIZE;

			ptep++;

		}



		pl2p++;

	}



	ptr = (unsigned long *)__pa(&max_pfn_mapped);

	/* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */

	*ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;



	ptr = (unsigned long *)__pa(&_brk_end);

	*ptr = (unsigned long)ptep + PAGE_OFFSET;

}

arch/x86/kernel/head_32.S

+7 −114
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <asm/nops.h>

#include <asm/bootparam.h>

#include <asm/export.h>

#include <asm/pgtable_32.h>



/* Physical address */

#define pa(X) ((X) - __PAGE_OFFSET)
@@ -41,43 +42,9 @@ 
#define X86_CAPABILITY	new_cpu_data+CPUINFO_x86_capability

#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.

 * We need:

 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)

 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)

 *

 * Modulo rounding, each megabyte assigned here requires a kilobyte of

 * memory, which is currently unreclaimed.

 *

 * This should be a multiple of a page.

 *

 * KERNEL_IMAGE_SIZE should be greater than pa(_end)

 * and small than max_low_pfn, otherwise will waste some page table entries

 */



#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 SIZEOF_PTREGS 17*4



/*

 * Number of possible pages in the lowmem region.

 *

 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a

 * gas warning about overflowing shift count when gas has been compiled

 * with only a host target support using a 32-bit type for internal

 * representation.

 */

LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT)



/* Enough space to fit pagetables for the low memory linear map */

MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT



/*

 * Worst-case size of the kernel mapping we need to make:

 * a relocatable kernel can live anywhere in lowmem, so we need to be able
@@ -160,90 +127,15 @@ ENTRY(startup_32) 
	call load_ucode_bsp

#endif



/*

 * 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.

 */

#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)

	/* Create early pagetables. */

	call  mk_early_pgtbl_32



	/* Do early initialization of the fixmap area */

	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax

#ifdef  CONFIG_X86_PAE

#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */

	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

#else

	movl %eax,pa(initial_page_table+0xffc)

#endif
@@ -666,6 +558,7 @@ ENTRY(setup_once_ref) 
__PAGE_ALIGNED_BSS

	.align PAGE_SIZE

#ifdef CONFIG_X86_PAE

.globl initial_pg_pmd

initial_pg_pmd:

	.fill 1024*KPMDS,4,0

#else