x86: remove 32-bit versions of readq()/writeq()
The presense of a writeq() implementation on 32-bit x86 that splits the
64-bit write into two 32-bit writes turns out to break the mpt2sas driver
(and in general is risky for drivers as was discussed in
<http://lkml.kernel.org/r/adaab6c1h7c.fsf@cisco.com>). To fix this,
revert 2c5643b1c5c7 ("x86: provide readq()/writeq() on 32-bit too") and
follow-on cleanups.
This unfortunately leads to pushing non-atomic definitions of readq() and
write() to various x86-only drivers that in the meantime started using the
definitions in the x86 version of <asm/io.h>. However as discussed
exhaustively, this is actually the right thing to do, because the right
way to split a 64-bit transaction is hardware dependent and therefore
belongs in the hardware driver (eg mpt2sas needs a spinlock to make sure
no other accesses occur in between the two halves of the access).
Build tested on 32- and 64-bit x86 allmodconfig.
Link: http://lkml.kernel.org/r/x86-32-writeq-is-broken@mdm.bga.com
Acked-by: Hitoshi Mitake <h.mitake@gmail.com>
Cc: Kashyap Desai <Kashyap.Desai@lsi.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Jason Uhlenkott <juhlenko@akamai.com>
Acked-by: James Bottomley <James.Bottomley@parallels.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 0722730..d02804d 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -38,7 +38,6 @@
#include <linux/string.h>
#include <linux/compiler.h>
-#include <asm-generic/int-ll64.h>
#include <asm/page.h>
#include <xen/xen.h>
@@ -87,27 +86,6 @@
build_mmio_read(readq, "q", unsigned long, "=r", :"memory")
build_mmio_write(writeq, "q", unsigned long, "r", :"memory")
-#else
-
-static inline __u64 readq(const volatile void __iomem *addr)
-{
- const volatile u32 __iomem *p = addr;
- u32 low, high;
-
- low = readl(p);
- high = readl(p + 1);
-
- return low + ((u64)high << 32);
-}
-
-static inline void writeq(__u64 val, volatile void __iomem *addr)
-{
- writel(val, addr);
- writel(val >> 32, addr+4);
-}
-
-#endif
-
#define readq_relaxed(a) readq(a)
#define __raw_readq(a) readq(a)
@@ -117,6 +95,8 @@
#define readq readq
#define writeq writeq
+#endif
+
/**
* virt_to_phys - map virtual addresses to physical
* @address: address to remap