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Message-ID: <2e2038d2-00b5-4f54-884f-d04d7165bbf5@paulmck-laptop>
Date: Thu, 30 May 2024 11:21:40 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: Russell King <linux@...linux.org.uk>,
Naresh Kamboju <naresh.kamboju@...aro.org>,
open list <linux-kernel@...r.kernel.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
lkft-triage@...ts.linaro.org,
Linux Regressions <regressions@...ts.linux.dev>,
rcu <rcu@...r.kernel.org>, Dan Carpenter <dan.carpenter@...aro.org>,
Joel Fernandes <joel@...lfernandes.org>, eeraj.upadhyay@...nel.org,
John Ogness <john.ogness@...utronix.de>,
Mark Brown <broonie@...nel.org>
Subject: Re: arm-linux-gnueabihf-ld:
kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to
`__bad_cmpxchg' follow
On Thu, May 30, 2024 at 08:05:50PM +0200, Arnd Bergmann wrote:
> On Thu, May 30, 2024, at 19:24, Paul E. McKenney wrote:
> > On Thu, May 30, 2024 at 09:37:21AM -0700, Paul E. McKenney wrote:
> >> On Thu, May 30, 2024 at 03:27:58PM +0200, Arnd Bergmann wrote:
>
> > And for an untested first attempt at a fix.
> >
> > What did I mess up this time? ;-)
> >
>
> I think only the comment:
>
> >
> > switch (size) {
> > -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
> > +#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
> > + case 1:
> > + oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);
> > + break;
> > +#else
>
> "min ARCH >= ARMv6K" now applies to the #else side, while the
> #if side is the early ARMv6 (pre-v6K).
Good catch!
I plan to fold the following into the original with attribution.
Thanx, Paul
------------------------------------------------------------------------
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h
index fd9b99f4dca46..34674a4118755 100644
--- a/arch/arm/include/asm/cmpxchg.h
+++ b/arch/arm/include/asm/cmpxchg.h
@@ -162,11 +162,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
prefetchw((const void *)ptr);
switch (size) {
-#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
+#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */
case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);
break;
-#else
+#else /* min ARCH >= ARMv6K */
case 1:
do {
asm volatile("@ __cmpxchg1\n"
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