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Re: Bug#963108: perl: Please include minor patch to fix FTBFS on m68k


On 6/19/20 8:22 AM, John Paul Adrian Glaubitz wrote:
> The attached patch fixes the problem by adding an additional 16 bits padding
> before the opslot member which causes the alignment of opslot to be 32 bits.

Attaching a patch with a better commit message for explanation.


 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913
>From 8cd015a5cc230105bdcb8c33db80ef9f06b1c670 Mon Sep 17 00:00:00 2001
From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Date: Fri, 19 Jun 2020 08:33:33 +0200
Subject: [PATCH] op.h: Add additional padding to struct opslab to ensure
 proper alignment

Perl crashes with a segmentation fault on m68k due to an alignment issue.
On m68k, the natural alignment is 16 bits which causes the opslot
member of "struct opslab" to be aligned at a 16-bit offset.

On other 32-bit and 64-bit architectures, the natural alignment is at
least 32 bits, so the offset is always guaranteed to be 32-bit aligned.
Fix this by adding an additional 16 bits padding before the opslot member
which causes the offset of oplab_slots to be 32-bit aligned.

On architectures which have a natural alignment of at least 32 bits,
the padding does not affect the alignment, offsets or struct size.
 op.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/op.h b/op.h
index fc21f03cda..fb9f538e23 100644
--- a/op.h
+++ b/op.h
@@ -714,6 +714,7 @@ struct opslab {
     bool	opslab_readonly;
 # endif
+    U16         opslab_padding;		/* padding to ensure proper alignment */
     OPSLOT	opslab_slots;		/* slots begin here */

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