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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
This commit is contained in:
H. Peter Anvin 2011-05-02 14:33:24 -07:00
parent 2be19102b7
commit 7806a49ab6
1 changed files with 6 additions and 6 deletions
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12
arch/x86/kernel/reboot_32.S
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@ -21,26 +21,26 @@ r_base = .
/* 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