Commit ccf3fe02 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by H. Peter Anvin
Browse files

x86-32: use brk segment for allocating initial kernel pagetable 



Impact: use new interface instead of previous ad hoc implementation

Rather than having special purpose init_pg_table_start/end variables
to delimit the kernel pagetable built by head_32.S, just use the brk
mechanism to extend the bss for the new pagetable.

This patch removes init_pg_table_start/end and pg0, defines __brk_base
(which is page-aligned and immediately follows _end), initializes
the brk region to start there, and uses it for the 32-bit pagetable.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 5368a2be

arch/x86/include/asm/pgtable_32.h

+0 −3
Original line number Diff line number Diff line
@@ -42,9 +42,6 @@ extern void set_pmd_pfn(unsigned long, unsigned long, pgprot_t); 
 */

#undef TEST_ACCESS_OK



/* The boot page tables (all created as a single array) */

extern unsigned long pg0[];



#ifdef CONFIG_X86_PAE

# include <asm/pgtable-3level.h>

#else

arch/x86/include/asm/setup.h

+0 −3
Original line number Diff line number Diff line
@@ -109,9 +109,6 @@ void *extend_brk(size_t size, size_t align); 
void __init i386_start_kernel(void);

extern void probe_roms(void);



extern unsigned long init_pg_tables_start;

extern unsigned long init_pg_tables_end;



#else

void __init x86_64_start_kernel(char *real_mode);

void __init x86_64_start_reservations(char *real_mode_data);

arch/x86/kernel/head32.c

+0 −3
Original line number Diff line number Diff line
@@ -29,9 +29,6 @@ void __init i386_start_kernel(void) 
		reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");

	}

#endif

	reserve_early(init_pg_tables_start, init_pg_tables_end,

			"INIT_PG_TABLE");



	reserve_ebda_region();



	/*

arch/x86/kernel/head_32.S

+7 −7
Original line number Diff line number Diff line
@@ -167,7 +167,7 @@ num_subarch_entries = (. - subarch_entries) / 4 
/*

 * Initialize page tables.  This creates a PDE and a set of page

 * tables, which are located immediately beyond _end.  The variable

 * init_pg_tables_end is set up to point to the first "safe" location.

 * _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+sizeof(page tables)+INIT_MAP_BEYOND_END.

 *
@@ -190,8 +190,7 @@ default_entry: 


	xorl %ebx,%ebx				/* %ebx is kept at zero */



	movl $pa(pg0), %edi

	movl %edi, pa(init_pg_tables_start)

	movl $pa(__brk_base), %edi

	movl $pa(swapper_pg_pmd), %edx

	movl $PTE_IDENT_ATTR, %eax

10:
@@ -216,7 +215,8 @@ default_entry: 
	cmpl %ebp,%eax

	jb 10b

1:

	movl %edi,pa(init_pg_tables_end)

	addl $__PAGE_OFFSET, %edi

	movl %edi, pa(_brk_end)

	shrl $12, %eax

	movl %eax, pa(max_pfn_mapped)
@@ -227,8 +227,7 @@ default_entry: 


page_pde_offset = (__PAGE_OFFSET >> 20);



	movl $pa(pg0), %edi

	movl %edi, pa(init_pg_tables_start)

	movl $pa(__brk_base), %edi

	movl $pa(swapper_pg_dir), %edx

	movl $PTE_IDENT_ATTR, %eax

10:
@@ -249,7 +248,8 @@ page_pde_offset = (__PAGE_OFFSET >> 20); 
	leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp

	cmpl %ebp,%eax

	jb 10b

	movl %edi,pa(init_pg_tables_end)

	addl $__PAGE_OFFSET, %edi

	movl %edi, pa(_brk_end)

	shrl $12, %eax

	movl %eax, pa(max_pfn_mapped)

arch/x86/kernel/setup.c

+0 −6
Original line number Diff line number Diff line
@@ -161,12 +161,6 @@ static struct resource bss_resource = { 




#ifdef CONFIG_X86_32

/* This value is set up by the early boot code to point to the value

   immediately after the boot time page tables.  It contains a *physical*

   address, and must not be in the .bss segment! */

unsigned long init_pg_tables_start __initdata = ~0UL;

unsigned long init_pg_tables_end __initdata = ~0UL;



static struct resource video_ram_resource = {

	.name	= "Video RAM area",

	.start	= 0xa0000,

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