[klibc] fwd: fix up ARM assembly to use 'bx lr' in place of 'mov pc, lr'.

On Wed, Feb 16, 2011 at 11:50 PM, Kirill A. Shutemov
[off-list ref] wrote:

On Thu, Feb 17, 2011 at 12:06:48AM +0100, maximilian attems wrote:

quoted

hello vorlon,

got notified of your patch,
will apply next days upstream unless some critiques are voiced on ml.
thanks.

--
maks


----- Forwarded message from Steve Langasek [off-list ref] -----

Date: Wed, 16 Feb 2011 22:05:42 -0000
From: Steve Langasek <redacted>
Subject: [Bug 527720] Re: thumb2 porting issues identified: klibc uses mov.*pc


I've also touched it up to be mergeable with Debian (support v4t builds
with #ifdef).

Confirmed that installing the resulting klibc packages on my beagleboard
gives me a successfully-booting initramfs with klibc; and the
vfork/setjmptest test cases all pass in the klibc package tree.

Fixes: https://bugs.launchpad.net/ubuntu/+source/klibc/+bug/527720

--- klibc-1.5.20.orig/usr/klibc/arch/arm/vfork.S
+++ klibc-1.5.20/usr/klibc/arch/arm/vfork.S

@@ -25,7 +25,11 @@ vfork:

? ? ? ? ?ldrcs ? ? ? ?r3, 1f
? ? ? ? ?mvncs ? ? ? ?r0, #0
? ? ? ? ?strcs ? ? ? ?r2, [r3]
+#if defined (___ARM_ARCH_4T__) || defined (__ARM_ARCH_4__)

NAK. ARMv4T supports bx intruction. ARMv4 doesn't.

You're strictly correct.  My original rationale was to ensure there is
no disruption for people building for v4/v4T -- since the more
restricted functionality of Thumb-1 means people tend not to use it to
build the whole distro anyway.

If people using <v5 are prepared to accept the change, I've got no
problem with changing the #ifs to #ifdef __ARM_ARCH_4__

We can't get rid of the #ifdef though, unless we can persuade everyone
targeting v4 to build with gcc/as -march=armv4t + ld --fix-v4bx
(unlikely).

Cheers
---Dave