linux-kernel - [PATCH 1/2] futex: mark futex_detect

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Date:   Thu,  7 Mar 2019 10:14:48 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Russell King <linux@...linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Davidlohr Bueso <dave@...olabs.net>,
        Elena Reshetova <elena.reshetova@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] futex: mark futex_detect_cmpxchg() as 'noinline'

On 32-bit ARM, I got a link failure in futex_init() when building
with clang in some random configurations:

kernel/futex.o:(.text.fixup+0x5c): relocation truncated to fit: R_ARM_JUMP24 against `.init.text'

As far as I can tell, the problem is that a branch is over 16MB
apart in those configurations, but only if it branches back to
the init text.

Marking the futex_detect_cmpxchg() function as noinline and
not __init avoids the problem for me.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 kernel/futex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index c3b73b0311bc..dda77ed9f445 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3849,7 +3849,7 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
 }
 #endif /* CONFIG_COMPAT_32BIT_TIME */
 
-static void __init futex_detect_cmpxchg(void)
+static noinline void futex_detect_cmpxchg(void)
 {
 #ifndef CONFIG_HAVE_FUTEX_CMPXCHG
 	u32 curval;
-- 
2.20.0