Commit d50d8fe1 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

x86, mm: Initialize initial_page_table before paravirt jumps 



v2.6.36-rc8-54-gb40827f (x86-32, mm: Add an initial page table
for core bootstrapping) made x86 boot using initial_page_table
and broke lguest.

For 2.6.37 we simply cut & paste the initialization code into
lguest (da32dac1 "lguest: populate initial_page_table"), now
we fix it properly by doing that initialization before the
paravirt jump.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarJeremy Fitzhardinge <jeremy@goop.org>
Cc: lguest <lguest@ozlabs.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <201101041720.54535.rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 387c31c7

arch/x86/kernel/head_32.S

+39 −38
Original line number Diff line number Diff line
@@ -139,39 +139,6 @@ ENTRY(startup_32) 
	movl %eax, pa(olpc_ofw_pgd)

#endif



#ifdef CONFIG_PARAVIRT

	/* This is can only trip for a broken bootloader... */

	cmpw $0x207, pa(boot_params + BP_version)

	jb default_entry



	/* Paravirt-compatible boot parameters.  Look to see what architecture

		we're booting under. */

	movl pa(boot_params + BP_hardware_subarch), %eax

	cmpl $num_subarch_entries, %eax

	jae bad_subarch



	movl pa(subarch_entries)(,%eax,4), %eax

	subl $__PAGE_OFFSET, %eax

	jmp *%eax



bad_subarch:

WEAK(lguest_entry)

WEAK(xen_entry)

	/* Unknown implementation; there's really

	   nothing we can do at this point. */

	ud2a



	__INITDATA



subarch_entries:

	.long default_entry		/* normal x86/PC */

	.long lguest_entry		/* lguest hypervisor */

	.long xen_entry			/* Xen hypervisor */

	.long default_entry		/* Moorestown MID */

num_subarch_entries = (. - subarch_entries) / 4

.previous

#endif /* CONFIG_PARAVIRT */



/*

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

 * tables, which are located immediately beyond __brk_base.  The variable
@@ -181,7 +148,6 @@ num_subarch_entries = (. - subarch_entries) / 4 
 *

 * Note that the stack is not yet set up!

 */

default_entry:

#ifdef CONFIG_X86_PAE



	/*
@@ -261,7 +227,42 @@ page_pde_offset = (__PAGE_OFFSET >> 20); 
	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax

	movl %eax,pa(initial_page_table+0xffc)

#endif

	jmp 3f



#ifdef CONFIG_PARAVIRT

	/* This is can only trip for a broken bootloader... */

	cmpw $0x207, pa(boot_params + BP_version)

	jb default_entry



	/* Paravirt-compatible boot parameters.  Look to see what architecture

		we're booting under. */

	movl pa(boot_params + BP_hardware_subarch), %eax

	cmpl $num_subarch_entries, %eax

	jae bad_subarch



	movl pa(subarch_entries)(,%eax,4), %eax

	subl $__PAGE_OFFSET, %eax

	jmp *%eax



bad_subarch:

WEAK(lguest_entry)

WEAK(xen_entry)

	/* Unknown implementation; there's really

	   nothing we can do at this point. */

	ud2a



	__INITDATA



subarch_entries:

	.long default_entry		/* normal x86/PC */

	.long lguest_entry		/* lguest hypervisor */

	.long xen_entry			/* Xen hypervisor */

	.long default_entry		/* Moorestown MID */

num_subarch_entries = (. - subarch_entries) / 4

.previous

#else

	jmp default_entry

#endif /* CONFIG_PARAVIRT */



/*

 * Non-boot CPU entry point; entered from trampoline.S

 * We can't lgdt here, because lgdt itself uses a data segment, but
@@ -282,7 +283,7 @@ ENTRY(startup_32_smp) 
	movl %eax,%fs

	movl %eax,%gs

#endif /* CONFIG_SMP */

3:

default_entry:



/*

 *	New page tables may be in 4Mbyte page mode and may
@@ -622,13 +623,13 @@ ENTRY(initial_code) 
__PAGE_ALIGNED_BSS

	.align PAGE_SIZE_asm

#ifdef CONFIG_X86_PAE

ENTRY(initial_pg_pmd)

initial_pg_pmd:

	.fill 1024*KPMDS,4,0

#else

ENTRY(initial_page_table)

	.fill 1024,4,0

#endif

ENTRY(initial_pg_fixmap)

initial_pg_fixmap:

	.fill 1024,4,0

ENTRY(empty_zero_page)

	.fill 4096,1,0

arch/x86/lguest/i386_head.S

+0 −105
Original line number Diff line number Diff line
@@ -4,7 +4,6 @@ 
#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
@@ -38,113 +37,9 @@ 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

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