linux-kernel - [PATCH] frv: Declare jiffies to be located in the .data section

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Date:   Tue, 16 May 2017 15:13:33 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     David Howells <dhowells@...hat.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:     linux-kernel@...r.kernel.org, Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH] frv: Declare jiffies to be located in the .data section

Commit 7c30f352c852 ("jiffies.h: declare jiffies and jiffies_64 with
____cacheline_aligned_in_smp") removed a section specification from the
jiffies declaration that caused conflicts on some platforms. Unfortunately
this change broke the build for frv:

kernel/built-in.o: In function `__do_softirq':
(.text+0x6460): relocation truncated to fit: R_FRV_GPREL12 against symbol
    `jiffies' defined in *ABS* section in .tmp_vmlinux1
kernel/built-in.o: In function `__do_softirq':
(.text+0x6574): relocation truncated to fit: R_FRV_GPREL12 against symbol
    `jiffies' defined in *ABS* section in .tmp_vmlinux1
kernel/built-in.o: In function `pwq_activate_delayed_work':
workqueue.c:(.text+0x15b9c): relocation truncated to fit: R_FRV_GPREL12 against
    symbol `jiffies' defined in *ABS* section in .tmp_vmlinux1
...

Add __jiffy_arch_data to the declaration of jiffies and use it on frv to
include the section specification. For all other platforms __jiffy_arch_data
(currently) has no effect.

Fixes: 7c30f352c852 ("jiffies.h: declare jiffies and jiffies_64 with
____cacheline_aligned_in_smp")
Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 arch/frv/include/asm/timex.h | 6 ++++++
 include/linux/jiffies.h      | 6 +++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/frv/include/asm/timex.h b/arch/frv/include/asm/timex.h
index a89bddefdacf..139093fab326 100644
--- a/arch/frv/include/asm/timex.h
+++ b/arch/frv/include/asm/timex.h
@@ -16,5 +16,11 @@ static inline cycles_t get_cycles(void)
 #define vxtime_lock()		do {} while (0)
 #define vxtime_unlock()		do {} while (0)
 
+/* This attribute is used in include/linux/jiffies.h alongside with
+ * __cacheline_aligned_in_smp. It is assumed that __cacheline_aligned_in_smp
+ * for frv does not contain another section specification.
+ */
+#define __jiffy_arch_data	__attribute__((__section__(".data")))
+
 #endif
 
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 36872fbb815d..734377ad42e9 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -64,13 +64,17 @@ extern int register_refined_jiffies(long clock_tick_rate);
 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
 #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
 
+#ifndef __jiffy_arch_data
+#define __jiffy_arch_data
+#endif
+
 /*
  * The 64-bit value is not atomic - you MUST NOT read it
  * without sampling the sequence number in jiffies_lock.
  * get_jiffies_64() will do this for you as appropriate.
  */
 extern u64 __cacheline_aligned_in_smp jiffies_64;
-extern unsigned long volatile __cacheline_aligned_in_smp jiffies;
+extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies;
 
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void);
-- 
2.13.0.303.g4ebf302169-goog