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[MIPS] R4000/R4400 errata workarounds
This is the gereric part of R4000/R4400 errata workarounds. They include compiler and assembler support as well as some source code modifications to address the problems with some combinations of multiply/divide+shift instructions as well as the daddi and daddiu instructions. Changes included are as follows: 1. New Kconfig options to select workarounds by platforms as necessary. 2. Arch top-level Makefile to pass necessary options to the compiler; also incompatible configurations are detected (-mno-sym32 unsupported as horribly intrusive for little gain). 3. Bug detection updated and shuffled -- the multiply/divide+shift problem is lethal enough that if not worked around it makes the kernel crash in time_init() because of a division by zero; the daddiu erratum might also trigger early potentially, though I have not observed it. On the other hand the daddi detection code requires the exception subsystem to have been initialised (and is there mainly for information). 4. r4k_daddiu_bug() added so that the existence of the erratum can be queried by code at the run time as necessary; useful for generated code like TLB fault and copy/clear page handlers. 5. __udelay() updated as it uses multiplication in inline assembly. Note that -mdaddi requires modified toolchain (which has been maintained by myself and available from my site for ~4years now -- versions covered are GCC 2.95.4 - 4.1.2 and binutils from 2.13 onwards). The -mfix-r4000 and -mfix-r4400 have been standard for a while though. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Maciej W. Rozycki
Ralf Baechle
parent
2b22c034d0
commit
20d60d9973
7 changed files with 148 additions and 30 deletions
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@ -91,6 +91,9 @@ config MACH_DECSTATION
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select BOOT_ELF32
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select CEVT_R4K
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select CSRC_R4K
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select CPU_DADDI_WORKAROUNDS if 64BIT
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select CPU_R4000_WORKAROUNDS if 64BIT
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select CPU_R4400_WORKAROUNDS if 64BIT
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select DMA_NONCOHERENT
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select NO_IOPORT
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select IRQ_CPU
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@ -1605,6 +1608,19 @@ config CPU_HAS_SYNC
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config GENERIC_CLOCKEVENTS_BROADCAST
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bool
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#
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# CPU non-features
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#
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config CPU_DADDI_WORKAROUNDS
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bool
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config CPU_R4000_WORKAROUNDS
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bool
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select CPU_R4400_WORKAROUNDS
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config CPU_R4400_WORKAROUNDS
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bool
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#
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# Use the generic interrupt handling code in kernel/irq/:
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#
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@ -141,6 +141,10 @@ cflags-$(CONFIG_CPU_R8000) += -march=r8000 -Wa,--trap
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cflags-$(CONFIG_CPU_R10000) += $(call cc-option,-march=r10000,-march=r8000) \
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-Wa,--trap
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cflags-$(CONFIG_CPU_R4000_WORKAROUNDS) += $(call cc-option,-mfix-r4000,)
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cflags-$(CONFIG_CPU_R4400_WORKAROUNDS) += $(call cc-option,-mfix-r4400,)
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cflags-$(CONFIG_CPU_DADDI_WORKAROUNDS) += $(call cc-option,-mno-daddi,)
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ifdef CONFIG_CPU_SB1
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ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
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MODFLAGS += -msb1-pass1-workarounds
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@ -602,9 +606,11 @@ ifdef CONFIG_64BIT
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endif
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endif
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ifeq ($(KBUILD_SYM32), y)
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ifeq ($(call cc-option-yn,-msym32), y)
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cflags-y += -msym32 -DKBUILD_64BIT_SYM32
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ifeq ($(KBUILD_SYM32)$(call cc-option-yn,-msym32), yy)
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cflags-y += -msym32 -DKBUILD_64BIT_SYM32
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else
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ifeq ($(CONFIG_CPU_DADDI_WORKAROUNDS), y)
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$(error CONFIG_CPU_DADDI_WORKAROUNDS unsupported without -msym32)
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endif
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endif
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endif
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@ -18,6 +18,15 @@
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#include <asm/mipsregs.h>
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#include <asm/system.h>
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static char bug64hit[] __initdata =
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"reliable operation impossible!\n%s";
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static char nowar[] __initdata =
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"Please report to <linux-mips@linux-mips.org>.";
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static char r4kwar[] __initdata =
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"Enable CPU_R4000_WORKAROUNDS to rectify.";
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static char daddiwar[] __initdata =
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"Enable CPU_DADDI_WORKAROUNDS to rectify.";
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static inline void align_mod(const int align, const int mod)
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{
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asm volatile(
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@ -155,13 +164,7 @@ static inline void check_mult_sh(void)
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}
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printk("no.\n");
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panic("Reliable operation impossible!\n"
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#ifndef CONFIG_CPU_R4000
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"Configure for R4000 to enable the workaround."
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#else
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"Please report to <linux-mips@linux-mips.org>."
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#endif
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);
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panic(bug64hit, !R4000_WAR ? r4kwar : nowar);
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}
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static volatile int daddi_ov __initdata = 0;
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@ -233,15 +236,11 @@ static inline void check_daddi(void)
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}
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printk("no.\n");
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panic("Reliable operation impossible!\n"
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#if !defined(CONFIG_CPU_R4000) && !defined(CONFIG_CPU_R4400)
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"Configure for R4000 or R4400 to enable the workaround."
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#else
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"Please report to <linux-mips@linux-mips.org>."
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#endif
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);
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panic(bug64hit, !DADDI_WAR ? daddiwar : nowar);
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}
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int daddiu_bug __initdata = -1;
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static inline void check_daddiu(void)
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{
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long v, w, tmp;
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@ -281,7 +280,9 @@ static inline void check_daddiu(void)
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: "=&r" (v), "=&r" (w), "=&r" (tmp)
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: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
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if (v == w) {
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daddiu_bug = v != w;
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if (!daddiu_bug) {
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printk("no.\n");
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return;
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}
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@ -303,18 +304,16 @@ static inline void check_daddiu(void)
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}
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printk("no.\n");
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panic("Reliable operation impossible!\n"
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#if !defined(CONFIG_CPU_R4000) && !defined(CONFIG_CPU_R4400)
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"Configure for R4000 or R4400 to enable the workaround."
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#else
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"Please report to <linux-mips@linux-mips.org>."
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#endif
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);
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panic(bug64hit, !DADDI_WAR ? daddiwar : nowar);
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}
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void __init check_bugs64_early(void)
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{
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check_mult_sh();
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check_daddiu();
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}
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void __init check_bugs64(void)
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{
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check_mult_sh();
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check_daddi();
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check_daddiu();
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}
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@ -8,7 +8,7 @@
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* Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 01, 02, 03 Ralf Baechle
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* Copyright (C) 1996 Stoned Elipot
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* Copyright (C) 1999 Silicon Graphics, Inc.
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* Copyright (C) 2000 2001, 2002 Maciej W. Rozycki
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* Copyright (C) 2000, 2001, 2002, 2007 Maciej W. Rozycki
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*/
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#include <linux/init.h>
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#include <linux/ioport.h>
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@ -24,6 +24,7 @@
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#include <asm/addrspace.h>
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#include <asm/bootinfo.h>
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#include <asm/bugs.h>
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#include <asm/cache.h>
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#include <asm/cpu.h>
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#include <asm/sections.h>
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@ -561,6 +562,7 @@ void __init setup_arch(char **cmdline_p)
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}
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#endif
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cpu_report();
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check_bugs_early();
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#if defined(CONFIG_VT)
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#if defined(CONFIG_VGA_CONSOLE)
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@ -1,19 +1,34 @@
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/*
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* This is included by init/main.c to check for architecture-dependent bugs.
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*
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* Copyright (C) 2007 Maciej W. Rozycki
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*
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* Needs:
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* void check_bugs(void);
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*/
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#ifndef _ASM_BUGS_H
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#define _ASM_BUGS_H
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#include <linux/bug.h>
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#include <linux/delay.h>
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#include <asm/cpu.h>
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#include <asm/cpu-info.h>
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extern int daddiu_bug;
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extern void check_bugs64_early(void);
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extern void check_bugs32(void);
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extern void check_bugs64(void);
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static inline void check_bugs_early(void)
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{
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#ifdef CONFIG_64BIT
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check_bugs64_early();
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#endif
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}
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static inline void check_bugs(void)
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{
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unsigned int cpu = smp_processor_id();
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@ -25,4 +40,14 @@ static inline void check_bugs(void)
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#endif
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}
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static inline int r4k_daddiu_bug(void)
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{
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#ifdef CONFIG_64BIT
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WARN_ON(daddiu_bug < 0);
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return daddiu_bug != 0;
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#else
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return 0;
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#endif
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}
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#endif /* _ASM_BUGS_H */
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@ -6,13 +6,16 @@
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* Copyright (C) 1994 by Waldorf Electronics
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* Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
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* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
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* Copyright (C) 2007 Maciej W. Rozycki
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*/
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#ifndef _ASM_DELAY_H
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#define _ASM_DELAY_H
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#include <linux/param.h>
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#include <linux/smp.h>
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#include <asm/compiler.h>
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#include <asm/war.h>
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static inline void __delay(unsigned long loops)
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{
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@ -50,7 +53,7 @@ static inline void __delay(unsigned long loops)
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static inline void __udelay(unsigned long usecs, unsigned long lpj)
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{
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unsigned long lo;
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unsigned long hi, lo;
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/*
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* The rates of 128 is rounded wrongly by the catchall case
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@ -70,11 +73,16 @@ static inline void __udelay(unsigned long usecs, unsigned long lpj)
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: "=h" (usecs), "=l" (lo)
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: "r" (usecs), "r" (lpj)
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: GCC_REG_ACCUM);
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else if (sizeof(long) == 8)
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else if (sizeof(long) == 8 && !R4000_WAR)
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__asm__("dmultu\t%2, %3"
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: "=h" (usecs), "=l" (lo)
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: "r" (usecs), "r" (lpj)
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: GCC_REG_ACCUM);
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else if (sizeof(long) == 8 && R4000_WAR)
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__asm__("dmultu\t%3, %4\n\tmfhi\t%0"
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: "=r" (usecs), "=h" (hi), "=l" (lo)
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: "r" (usecs), "r" (lpj)
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: GCC_REG_ACCUM);
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__delay(usecs);
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}
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@ -4,12 +4,74 @@
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* for more details.
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*
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* Copyright (C) 2002, 2004, 2007 by Ralf Baechle
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* Copyright (C) 2007 Maciej W. Rozycki
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*/
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#ifndef _ASM_WAR_H
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#define _ASM_WAR_H
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#include <war.h>
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/*
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* Work around certain R4000 CPU errata (as implemented by GCC):
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*
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* - A double-word or a variable shift may give an incorrect result
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* if executed immediately after starting an integer division:
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* "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0",
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* erratum #28
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* "MIPS R4000MC Errata, Processor Revision 2.2 and 3.0", erratum
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* #19
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*
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* - A double-word or a variable shift may give an incorrect result
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* if executed while an integer multiplication is in progress:
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* "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0",
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* errata #16 & #28
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*
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* - An integer division may give an incorrect result if started in
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* a delay slot of a taken branch or a jump:
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* "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0",
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* erratum #52
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*/
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#ifdef CONFIG_CPU_R4000_WORKAROUNDS
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#define R4000_WAR 1
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#else
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#define R4000_WAR 0
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#endif
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/*
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* Work around certain R4400 CPU errata (as implemented by GCC):
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*
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* - A double-word or a variable shift may give an incorrect result
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* if executed immediately after starting an integer division:
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* "MIPS R4400MC Errata, Processor Revision 1.0", erratum #10
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* "MIPS R4400MC Errata, Processor Revision 2.0 & 3.0", erratum #4
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*/
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#ifdef CONFIG_CPU_R4400_WORKAROUNDS
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#define R4400_WAR 1
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#else
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#define R4400_WAR 0
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#endif
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/*
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* Work around the "daddi" and "daddiu" CPU errata:
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*
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* - The `daddi' instruction fails to trap on overflow.
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* "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0",
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* erratum #23
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*
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* - The `daddiu' instruction can produce an incorrect result.
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* "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0",
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* erratum #41
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* "MIPS R4000MC Errata, Processor Revision 2.2 and 3.0", erratum
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* #15
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* "MIPS R4400PC/SC Errata, Processor Revision 1.0", erratum #7
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* "MIPS R4400MC Errata, Processor Revision 1.0", erratum #5
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*/
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#ifdef CONFIG_CPU_DADDI_WORKAROUNDS
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#define DADDI_WAR 1
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#else
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#define DADDI_WAR 0
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#endif
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/*
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* Another R4600 erratum. Due to the lack of errata information the exact
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* technical details aren't known. I've experimentally found that disabling
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