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i386: paravirt boot sequence
This patch uses the updated boot protocol to do paravirtualized boot.
If the boot version is >= 2.07, then it will do two things:
1. Check the bootparams loadflags to see if we should reload the
segment registers and clear interrupts. This is appropriate
for normal native boot and some paravirtualized environments, but
inapproprate for others.
2. Check the hardware architecture, and dispatch to the appropriate
kernel entrypoint. If the bootloader doesn't set this, then we
simply do the normal boot sequence.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell
Linus Torvalds
parent
214541d1f3
commit
a24e785111
@ -27,13 +27,22 @@
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#include <asm/segment.h>
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#include <asm/page.h>
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#include <asm/boot.h>
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#include <asm/asm-offsets.h>
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.section ".text.head","ax",@progbits
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.globl startup_32
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startup_32:
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cld
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cli
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/* check to see if KEEP_SEGMENTS flag is meaningful */
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cmpw $0x207, BP_version(%esi)
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jb 1f
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/* test KEEP_SEGMENTS flag to see if the bootloader is asking
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* us to not reload segments */
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testb $(1<<6), BP_loadflags(%esi)
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jnz 2f
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1: cli
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movl $(__BOOT_DS),%eax
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movl %eax,%ds
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movl %eax,%es
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@ -41,6 +50,8 @@ startup_32:
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movl %eax,%gs
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movl %eax,%ss
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2: cld
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/* Calculate the delta between where we were compiled to run
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* at and where we were actually loaded at. This can only be done
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* with a short local call on x86. Nothing else will tell us what
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@ -247,6 +247,9 @@ static void putstr(const char *s)
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int x,y,pos;
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char c;
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if (RM_SCREEN_INFO.orig_video_mode == 0 && lines == 0 && cols == 0)
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return;
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x = RM_SCREEN_INFO.orig_x;
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y = RM_SCREEN_INFO.orig_y;
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@ -119,7 +119,7 @@ _start:
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# Part 2 of the header, from the old setup.S
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.ascii "HdrS" # header signature
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.word 0x0206 # header version number (>= 0x0105)
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.word 0x0207 # header version number (>= 0x0105)
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# or else old loadlin-1.5 will fail)
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.globl realmode_swtch
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realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
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@ -214,6 +214,11 @@ cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
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#added with boot protocol
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#version 2.06
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hardware_subarch: .long 0 # subarchitecture, added with 2.07
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# default to 0 for normal x86 PC
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hardware_subarch_data: .quad 0
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# End of setup header #####################################################
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.section ".inittext", "ax"
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@ -79,22 +79,30 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_
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*/
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.section .text.head,"ax",@progbits
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ENTRY(startup_32)
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/* check to see if KEEP_SEGMENTS flag is meaningful */
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cmpw $0x207, BP_version(%esi)
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jb 1f
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/* test KEEP_SEGMENTS flag to see if the bootloader is asking
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us to not reload segments */
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testb $(1<<6), BP_loadflags(%esi)
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jnz 2f
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/*
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* Set segments to known values.
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*/
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cld
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lgdt boot_gdt_descr - __PAGE_OFFSET
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1: lgdt boot_gdt_descr - __PAGE_OFFSET
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movl $(__BOOT_DS),%eax
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movl %eax,%ds
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movl %eax,%es
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movl %eax,%fs
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movl %eax,%gs
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2:
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/*
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* Clear BSS first so that there are no surprises...
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* No need to cld as DF is already clear from cld above...
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*/
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cld
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xorl %eax,%eax
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movl $__bss_start - __PAGE_OFFSET,%edi
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movl $__bss_stop - __PAGE_OFFSET,%ecx
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@ -128,6 +136,35 @@ ENTRY(startup_32)
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movsl
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1:
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#ifdef CONFIG_PARAVIRT
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cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)
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jb default_entry
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/* Paravirt-compatible boot parameters. Look to see what architecture
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we're booting under. */
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movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax
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cmpl $num_subarch_entries, %eax
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jae bad_subarch
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movl subarch_entries - __PAGE_OFFSET(,%eax,4), %eax
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subl $__PAGE_OFFSET, %eax
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jmp *%eax
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bad_subarch:
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WEAK(lguest_entry)
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WEAK(xen_entry)
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/* Unknown implementation; there's really
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nothing we can do at this point. */
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ud2a
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.data
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subarch_entries:
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.long default_entry /* normal x86/PC */
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.long lguest_entry /* lguest hypervisor */
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.long xen_entry /* Xen hypervisor */
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num_subarch_entries = (. - subarch_entries) / 4
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.previous
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#endif /* CONFIG_PARAVIRT */
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/*
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* Initialize page tables. This creates a PDE and a set of page
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* tables, which are located immediately beyond _end. The variable
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@ -140,6 +177,7 @@ ENTRY(startup_32)
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*/
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page_pde_offset = (__PAGE_OFFSET >> 20);
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default_entry:
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movl $(pg0 - __PAGE_OFFSET), %edi
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movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
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movl $0x007, %eax /* 0x007 = PRESENT+RW+USER */
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