1 files changed, 41 insertions, 3 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 39677965e161..00b1c2c56454 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -79,22 +79,30 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_
 */
 .section .text.head,"ax",@progbits
 ENTRY(startup_32)
+        /* check to see if KEEP_SEGMENTS flag is meaningful */
+        cmpw $0x207, BP_version(%esi)
+        jb 1f
+        /* test KEEP_SEGMENTS flag to see if the bootloader is asking
+                us to not reload segments */
+        testb $(1<<6), BP_loadflags(%esi)
+        jnz 2f
 /*
 * Set segments to known values.
 */
-        cld
+1:      lgdt boot_gdt_descr - __PAGE_OFFSET
-        lgdt boot_gdt_descr - __PAGE_OFFSET
        movl $(__BOOT_DS),%eax
        movl %eax,%ds
        movl %eax,%es
        movl %eax,%fs
        movl %eax,%gs
+2:
 /*
 * Clear BSS first so that there are no surprises...
- * No need to cld as DF is already clear from cld above...
 */
+        cld
        xorl %eax,%eax
        movl $__bss_start - __PAGE_OFFSET,%edi
        movl $__bss_stop - __PAGE_OFFSET,%ecx
@@ -128,6 +136,35 @@ ENTRY(startup_32)
        movsl
 1:
+#ifdef CONFIG_PARAVIRT
+        cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)
+        jb default_entry
+        /* Paravirt-compatible boot parameters.  Look to see what architecture
+                we're booting under. */
+        movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax
+        cmpl $num_subarch_entries, %eax
+        jae bad_subarch
+        movl subarch_entries - __PAGE_OFFSET(,%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
+.data
+subarch_entries:
+        .long default_entry             /* normal x86/PC */
+        .long lguest_entry              /* lguest hypervisor */
+        .long xen_entry                 /* Xen hypervisor */
+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 _end.  The variable
@@ -140,6 +177,7 @@ ENTRY(startup_32)
 */
 page_pde_offset = (__PAGE_OFFSET >> 20);
+default_entry:
        movl $(pg0 - __PAGE_OFFSET), %edi
        movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
        movl $0x007, %eax                       /* 0x007 = PRESENT+RW+USER */

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 39677965e161..00b1c2c56454 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S
@@ -79,22 +79,30 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_
79	*/	79	*/
80	.section .text.head,"ax",@progbits	80	.section .text.head,"ax",@progbits
81	ENTRY(startup_32)	81	ENTRY(startup_32)
		82	/* check to see if KEEP_SEGMENTS flag is meaningful */
		83	cmpw $0x207, BP_version(%esi)
		84	jb 1f
		85
		86	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
		87	us to not reload segments */
		88	testb $(1<<6), BP_loadflags(%esi)
		89	jnz 2f
82		90
83	/*	91	/*
84	* Set segments to known values.	92	* Set segments to known values.
85	*/	93	*/
86	cld	94	1: lgdt boot_gdt_descr - __PAGE_OFFSET
87	lgdt boot_gdt_descr - __PAGE_OFFSET
88	movl $(__BOOT_DS),%eax	95	movl $(__BOOT_DS),%eax
89	movl %eax,%ds	96	movl %eax,%ds
90	movl %eax,%es	97	movl %eax,%es
91	movl %eax,%fs	98	movl %eax,%fs
92	movl %eax,%gs	99	movl %eax,%gs
		100	2:
93		101
94	/*	102	/*
95	* Clear BSS first so that there are no surprises...	103	* Clear BSS first so that there are no surprises...
96	* No need to cld as DF is already clear from cld above...
97	*/	104	*/
		105	cld
98	xorl %eax,%eax	106	xorl %eax,%eax
99	movl $__bss_start - __PAGE_OFFSET,%edi	107	movl $__bss_start - __PAGE_OFFSET,%edi
100	movl $__bss_stop - __PAGE_OFFSET,%ecx	108	movl $__bss_stop - __PAGE_OFFSET,%ecx
@@ -128,6 +136,35 @@ ENTRY(startup_32)
128	movsl	136	movsl
129	1:	137	1:
130		138
		139	#ifdef CONFIG_PARAVIRT
		140	cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)
		141	jb default_entry
		142
		143	/* Paravirt-compatible boot parameters. Look to see what architecture
		144	we're booting under. */
		145	movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax
		146	cmpl $num_subarch_entries, %eax
		147	jae bad_subarch
		148
		149	movl subarch_entries - __PAGE_OFFSET(,%eax,4), %eax
		150	subl $__PAGE_OFFSET, %eax
		151	jmp *%eax
		152
		153	bad_subarch:
		154	WEAK(lguest_entry)
		155	WEAK(xen_entry)
		156	/* Unknown implementation; there's really
		157	nothing we can do at this point. */
		158	ud2a
		159	.data
		160	subarch_entries:
		161	.long default_entry /* normal x86/PC */
		162	.long lguest_entry /* lguest hypervisor */
		163	.long xen_entry /* Xen hypervisor */
		164	num_subarch_entries = (. - subarch_entries) / 4
		165	.previous
		166	#endif /* CONFIG_PARAVIRT */
		167
131	/*	168	/*
132	* Initialize page tables. This creates a PDE and a set of page	169	* Initialize page tables. This creates a PDE and a set of page
133	* tables, which are located immediately beyond _end. The variable	170	* tables, which are located immediately beyond _end. The variable
@@ -140,6 +177,7 @@ ENTRY(startup_32)
140	*/	177	*/
141	page_pde_offset = (__PAGE_OFFSET >> 20);	178	page_pde_offset = (__PAGE_OFFSET >> 20);
142		179
		180	default_entry:
143	movl $(pg0 - __PAGE_OFFSET), %edi	181	movl $(pg0 - __PAGE_OFFSET), %edi
144	movl $(swapper_pg_dir - __PAGE_OFFSET), %edx	182	movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
145	movl $0x007, %eax /* 0x007 = PRESENT+RW+USER */	183	movl $0x007, %eax /* 0x007 = PRESENT+RW+USER */