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Commit 084ee1c6 authored by Jarkko Sakkinen's avatar Jarkko Sakkinen Committed by H. Peter Anvin
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x86, realmode: Relocator for realmode code 



Implements relocator for real mode code that is called
as part of setup_arch(). Processes segment relocations
and linear relocations. Real-mode code is relocated to
a free hole below 1 MB.

Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-4-git-send-email-jarkko.sakkinen@intel.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent b3266bd6

arch/x86/include/asm/realmode.h

0 → 100644
+26 −0
Original line number Original line Diff line number Diff line 
#ifndef _ARCH_X86_REALMODE_H

#define _ARCH_X86_REALMODE_H



#include <linux/types.h>

#include <asm/io.h>



/* This must match data at realmode.S */

struct real_mode_header {

	u32	text_start;

	u32	ro_end;

	u32	end;

} __attribute__((__packed__));



extern struct real_mode_header real_mode_header;

extern unsigned char *real_mode_base;



extern unsigned long init_rsp;

extern unsigned long initial_code;

extern unsigned long initial_gs;



extern unsigned char real_mode_blob[];

extern unsigned char real_mode_relocs[];



extern void __init setup_real_mode(void);



#endif /* _ARCH_X86_REALMODE_H */

arch/x86/kernel/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -36,6 +36,7 @@ obj-y += pci-iommu_table.o 
obj-y			+= resource.o

obj-y			+= resource.o





obj-y				+= trampoline.o trampoline_$(BITS).o

obj-y				+= trampoline.o trampoline_$(BITS).o

obj-y				+= realmode.o

obj-y				+= process.o

obj-y				+= process.o

obj-y				+= i387.o xsave.o

obj-y				+= i387.o xsave.o

obj-y				+= ptrace.o

obj-y				+= ptrace.o

arch/x86/kernel/realmode.c

0 → 100644
+79 −0
Original line number Original line Diff line number Diff line 
#include <linux/io.h>

#include <linux/memblock.h>



#include <asm/cacheflush.h>

#include <asm/pgtable.h>

#include <asm/realmode.h>



unsigned char *real_mode_base;

struct real_mode_header real_mode_header;



void __init setup_real_mode(void)

{

	phys_addr_t mem;

	u16 real_mode_seg;

	u32 *rel;

	u32 count;

	u32 *ptr;

	u16 *seg;

	int i;



	struct real_mode_header *header =

		(struct real_mode_header *) real_mode_blob;



	size_t size = PAGE_ALIGN(header->end);



	/* Has to be in very low memory so we can execute real-mode AP code. */

	mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);

	if (!mem)

		panic("Cannot allocate trampoline\n");



	real_mode_base = __va(mem);

	memblock_reserve(mem, size);



	printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",

	       real_mode_base, (unsigned long long)mem, size);



	memcpy(real_mode_base, real_mode_blob, size);



	real_mode_seg = __pa(real_mode_base) >> 4;

	rel = (u32 *) real_mode_relocs;



	/* 16-bit segment relocations. */

	count = rel[0];

	rel = &rel[1];

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

		seg = (u16 *) (real_mode_base + rel[i]);

		*seg = real_mode_seg;

	}



	/* 32-bit linear relocations. */

	count = rel[i];

	rel =  &rel[i + 1];

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

		ptr = (u32 *) (real_mode_base + rel[i]);

		*ptr += __pa(real_mode_base);

	}



	/* Copied header will contain relocated physical addresses. */

	memcpy(&real_mode_header, real_mode_base,

	       sizeof(struct real_mode_header));

}



/*

 * set_real_mode_permissions() gets called very early, to guarantee the

 * availability of low memory.  This is before the proper kernel page

 * tables are set up, so we cannot set page permissions in that

 * function.  Thus, we use an arch_initcall instead.

 */

static int __init set_real_mode_permissions(void)

{

	size_t all_size =

		PAGE_ALIGN(real_mode_header.end) -

		__pa(real_mode_base);



	set_memory_x((unsigned long) real_mode_base, all_size >> PAGE_SHIFT);

	return 0;

}



arch_initcall(set_real_mode_permissions);

arch/x86/kernel/setup.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -74,6 +74,7 @@ 
#include <asm/mtrr.h>

#include <asm/mtrr.h>

#include <asm/apic.h>

#include <asm/apic.h>

#include <asm/trampoline.h>

#include <asm/trampoline.h>

#include <asm/realmode.h>

#include <asm/e820.h>

#include <asm/e820.h>

#include <asm/mpspec.h>

#include <asm/mpspec.h>

#include <asm/setup.h>

#include <asm/setup.h>
@@ -918,6 +919,7 @@ void __init setup_arch(char **cmdline_p) 
			max_pfn_mapped<<PAGE_SHIFT);

			max_pfn_mapped<<PAGE_SHIFT);





	setup_trampolines();

	setup_trampolines();

	setup_real_mode();





	init_gbpages();

	init_gbpages();