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Commit 14500f14 authored by Boris Ostrovsky's avatar Boris Ostrovsky Committed by Greg Kroah-Hartman
Browse files

xen/PVH: Set up GS segment for stack canary 



commit 98014068328c5574de9a4a30b604111fd9d8f901 upstream.

We are making calls to C code (e.g. xen_prepare_pvh()) which may use
stack canary (stored in GS segment).

Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent de019e78

arch/x86/xen/xen-pvh.S

+25 −1
Original line number Diff line number Diff line
@@ -54,6 +54,9 @@ 
 * charge of setting up it's own stack, GDT and IDT.

 */



#define PVH_GDT_ENTRY_CANARY	4

#define PVH_CANARY_SEL		(PVH_GDT_ENTRY_CANARY * 8)



ENTRY(pvh_start_xen)

	cld
@@ -98,6 +101,12 @@ ENTRY(pvh_start_xen) 
	/* 64-bit entry point. */

	.code64

1:

	/* Set base address in stack canary descriptor. */

	mov $MSR_GS_BASE,%ecx

	mov $_pa(canary), %eax

	xor %edx, %edx

	wrmsr



	call xen_prepare_pvh



	/* startup_64 expects boot_params in %rsi. */
@@ -107,6 +116,17 @@ ENTRY(pvh_start_xen) 


#else /* CONFIG_X86_64 */



	/* Set base address in stack canary descriptor. */

	movl $_pa(gdt_start),%eax

	movl $_pa(canary),%ecx

	movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax)

	shrl $16, %ecx

	movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax)

	movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax)



	mov $PVH_CANARY_SEL,%eax

	mov %eax,%gs



	call mk_early_pgtbl_32



	mov $_pa(initial_page_table), %eax
@@ -150,9 +170,13 @@ gdt_start: 
	.quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* __KERNEL_CS */

#endif

	.quad GDT_ENTRY(0xc092, 0, 0xfffff) /* __KERNEL_DS */

	.quad GDT_ENTRY(0x4090, 0, 0x18)    /* PVH_CANARY_SEL */

gdt_end:



	.balign 4

	.balign 16

canary:

	.fill 48, 1, 0



early_stack:

	.fill 256, 1, 0

early_stack_end: