linux_dsm_epyc7002/include/asm-x86/io.h
Linus Torvalds c1f64a5800 x86: MMIO and gcc re-ordering issue
On Tue, 27 May 2008, Linus Torvalds wrote:
>
> Expecting people to fix up all drivers is simply not going to happen. And
> serializing things shouldn't be *that* expensive. People who cannot take
> the expense can continue to use the magic __raw_writel() etc stuff.

Of course, for non-x86, you kind of have to expect drivers to be
well-behaved, so non-x86 can probably avoid this simply because there are
less relevant drivers involved.

Here's a UNTESTED patch for x86 that may or may not compile and work, and
which serializes (on a compiler level) the IO accesses against regular
memory accesses.

__read[bwlq]()/__write[bwlq]() are not serialized with a :"memory"
barrier, although since they still use "asm volatile" I suspect that i
practice they are probably serial too. Did not look very closely at any
generated code (only did a trivial test to see that the code looks
*roughly* correct).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-02 12:29:31 +02:00

76 lines
2.3 KiB
C

#ifndef _ASM_X86_IO_H
#define _ASM_X86_IO_H
#define ARCH_HAS_IOREMAP_WC
#include <linux/compiler.h>
#define build_mmio_read(name, size, type, reg, barrier) \
static inline type name(const volatile void __iomem *addr) \
{ type ret; asm volatile("mov" size " %1,%0":"=" reg (ret) \
:"m" (*(volatile type __force *)addr) barrier); return ret; }
#define build_mmio_write(name, size, type, reg, barrier) \
static inline void name(type val, volatile void __iomem *addr) \
{ asm volatile("mov" size " %0,%1": :reg (val), \
"m" (*(volatile type __force *)addr) barrier); }
build_mmio_read(readb, "b", unsigned char, "q", :"memory")
build_mmio_read(readw, "w", unsigned short, "r", :"memory")
build_mmio_read(readl, "l", unsigned int, "r", :"memory")
build_mmio_read(__readb, "b", unsigned char, "q", )
build_mmio_read(__readw, "w", unsigned short, "r", )
build_mmio_read(__readl, "l", unsigned int, "r", )
build_mmio_write(writeb, "b", unsigned char, "q", :"memory")
build_mmio_write(writew, "w", unsigned short, "r", :"memory")
build_mmio_write(writel, "l", unsigned int, "r", :"memory")
build_mmio_write(__writeb, "b", unsigned char, "q", )
build_mmio_write(__writew, "w", unsigned short, "r", )
build_mmio_write(__writel, "l", unsigned int, "r", )
#define readb_relaxed(a) __readb(a)
#define readw_relaxed(a) __readw(a)
#define readl_relaxed(a) __readl(a)
#define __raw_readb __readb
#define __raw_readw __readw
#define __raw_readl __readl
#define __raw_writeb __writeb
#define __raw_writew __writew
#define __raw_writel __writel
#define mmiowb() barrier()
#ifdef CONFIG_X86_64
build_mmio_read(readq, "q", unsigned long, "r", :"memory")
build_mmio_read(__readq, "q", unsigned long, "r", )
build_mmio_write(writeq, "q", unsigned long, "r", :"memory")
build_mmio_write(__writeq, "q", unsigned long, "r", )
#define readq_relaxed(a) __readq(a)
#define __raw_readq __readq
#define __raw_writeq writeq
/* Let people know we have them */
#define readq readq
#define writeq writeq
#endif
#ifdef CONFIG_X86_32
# include "io_32.h"
#else
# include "io_64.h"
#endif
extern void *xlate_dev_mem_ptr(unsigned long phys);
extern void unxlate_dev_mem_ptr(unsigned long phys, void *addr);
extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,
unsigned long prot_val);
extern void __iomem *ioremap_wc(unsigned long offset, unsigned long size);
#endif /* _ASM_X86_IO_H */