x86, reboot: Fix relocations in reboot_32.S
The use of base for %ebx in this file is arbitrary, *except* that we
also use it to compute the real-mode segment. Therefore, make it so
that r_base really is the true address to which %ebx points.
This resolves kernel bugzilla 33302.
Reported-and-tested-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/n/tip-08os5wi3yq1no0y4i5m4z7he@git.kernel.org
diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
index 29092b3..1d5c46d 100644
--- a/arch/x86/kernel/reboot_32.S
+++ b/arch/x86/kernel/reboot_32.S
@@ -21,26 +21,26 @@
/* Get our own relocated address */
call 1f
1: popl %ebx
- subl $1b, %ebx
+ subl $(1b - r_base), %ebx
/* Compute the equivalent real-mode segment */
movl %ebx, %ecx
shrl $4, %ecx
/* Patch post-real-mode segment jump */
- movw dispatch_table(%ebx,%eax,2),%ax
- movw %ax, 101f(%ebx)
- movw %cx, 102f(%ebx)
+ movw (dispatch_table - r_base)(%ebx,%eax,2),%ax
+ movw %ax, (101f - r_base)(%ebx)
+ movw %cx, (102f - r_base)(%ebx)
/* Set up the IDT for real mode. */
- lidtl machine_real_restart_idt(%ebx)
+ lidtl (machine_real_restart_idt - r_base)(%ebx)
/*
* Set up a GDT from which we can load segment descriptors for real
* mode. The GDT is not used in real mode; it is just needed here to
* prepare the descriptors.
*/
- lgdtl machine_real_restart_gdt(%ebx)
+ lgdtl (machine_real_restart_gdt - r_base)(%ebx)
/*
* Load the data segment registers with 16-bit compatible values