From c1f64a58003fd2efaa725a857e269a15f765791a Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 27 May 2008 09:47:13 -0700 Subject: 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 --- include/asm-x86/io.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) (limited to 'include/asm-x86/io.h') diff --git a/include/asm-x86/io.h b/include/asm-x86/io.h index d5b11f60dbd0..8e9eca93f9b9 100644 --- a/include/asm-x86/io.h +++ b/include/asm-x86/io.h @@ -3,6 +3,62 @@ #define ARCH_HAS_IOREMAP_WC +#include + +#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 -- cgit v1.2.2 From 4583ed514ea9ac844a6eb02d33120beaedf6837f Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 25 Jun 2008 00:19:03 -0400 Subject: x86, 64-bit: unify early_ioremap The 32-bit early_ioremap will work equally well for 64-bit, so just use it. Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- include/asm-x86/io.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/asm-x86/io.h') diff --git a/include/asm-x86/io.h b/include/asm-x86/io.h index 8e9eca93f9b9..c63563df4ac8 100644 --- a/include/asm-x86/io.h +++ b/include/asm-x86/io.h @@ -72,4 +72,17 @@ 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); +/* + * early_ioremap() and early_iounmap() are for temporary early boot-time + * mappings, before the real ioremap() is functional. + * A boot-time mapping is currently limited to at most 16 pages. + */ +extern void early_ioremap_init(void); +extern void early_ioremap_clear(void); +extern void early_ioremap_reset(void); +extern void *early_ioremap(unsigned long offset, unsigned long size); +extern void early_iounmap(void *addr, unsigned long size); +extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys); + + #endif /* _ASM_X86_IO_H */ -- cgit v1.2.2 From 3ae960a598b9dfe87b29eb70738d91a13e692498 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 30 Jun 2008 10:33:47 +0200 Subject: - x86: move early_ioremap prototypes to io.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit now that the early-ioremap code is unified, move the prototypes too from io_32.h to io.h. this fixes: arch/x86/kernel/setup.c:531: error: implicit declaration of function ‘early_ioremap_init' on 64-bit. Signed-off-by: Ingo Molnar --- include/asm-x86/io.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/asm-x86/io.h') diff --git a/include/asm-x86/io.h b/include/asm-x86/io.h index c63563df4ac8..bf5d629b3a39 100644 --- a/include/asm-x86/io.h +++ b/include/asm-x86/io.h @@ -5,6 +5,20 @@ #include +/* + * early_ioremap() and early_iounmap() are for temporary early boot-time + * mappings, before the real ioremap() is functional. + * A boot-time mapping is currently limited to at most 16 pages. + */ +#ifndef __ASSEMBLY__ +extern void early_ioremap_init(void); +extern void early_ioremap_clear(void); +extern void early_ioremap_reset(void); +extern void *early_ioremap(unsigned long offset, unsigned long size); +extern void early_iounmap(void *addr, unsigned long size); +extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys); +#endif + #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) \ -- cgit v1.2.2