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Commit dbee8a0a authored by Roland Dreier's avatar Roland Dreier Committed by Linus Torvalds
Browse files

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 2c5643b1 ("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: default avatarHitoshi 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: default avatarJames Bottomley <James.Bottomley@parallels.com>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 818b667b

arch/x86/Kconfig

+0 −2
Original line number Diff line number Diff line
@@ -17,8 +17,6 @@ config X86_64 
config X86

	def_bool y

	select HAVE_AOUT if X86_32

	select HAVE_READQ

	select HAVE_WRITEQ

	select HAVE_UNSTABLE_SCHED_CLOCK

	select HAVE_IDE

	select HAVE_OPROFILE

arch/x86/include/asm/io.h

+2 −22
Original line number Diff line number Diff line
@@ -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_write(__writel, "l", unsigned int, "r", ) 
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 @@ static inline void writeq(__u64 val, volatile void __iomem *addr) 
#define readq			readq

#define writeq			writeq



#endif



/**

 *	virt_to_phys	-	map virtual addresses to physical

 *	@address: address to remap

drivers/acpi/apei/einj.c

+8 −0
Original line number Diff line number Diff line
@@ -101,6 +101,14 @@ static DEFINE_MUTEX(einj_mutex); 


static struct einj_parameter *einj_param;



#ifndef writeq

static inline void writeq(__u64 val, volatile void __iomem *addr)

{

	writel(val, addr);

	writel(val >> 32, addr+4);

}

#endif



static void einj_exec_ctx_init(struct apei_exec_context *ctx)

{

	apei_exec_ctx_init(ctx, einj_ins_type, ARRAY_SIZE(einj_ins_type),

drivers/acpi/atomicio.c

+4 −0
Original line number Diff line number Diff line
@@ -280,9 +280,11 @@ static int acpi_atomic_read_mem(u64 paddr, u64 *val, u32 width) 
	case 32:

		*val = readl(addr);

		break;

#ifdef readq

	case 64:

		*val = readq(addr);

		break;

#endif

	default:

		return -EINVAL;

	}
@@ -307,9 +309,11 @@ static int acpi_atomic_write_mem(u64 paddr, u64 val, u32 width) 
	case 32:

		writel(val, addr);

		break;

#ifdef writeq

	case 64:

		writeq(val, addr);

		break;

#endif

	default:

		return -EINVAL;

	}

drivers/edac/i3200_edac.c

+13 −0
Original line number Diff line number Diff line
@@ -101,6 +101,19 @@ struct i3200_priv { 


static int nr_channels;



#ifndef readq

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);

}

#endif



static int how_many_channels(struct pci_dev *pdev)

{

	unsigned char capid0_8b; /* 8th byte of CAPID0 */