From 20d60d9973c3b441902b0a3f4f6f7e7ade08f77d Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Tue, 23 Oct 2007 12:43:11 +0100 Subject: [PATCH] [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 Signed-off-by: Ralf Baechle --- arch/mips/Kconfig | 16 +++++++++ arch/mips/Makefile | 12 +++++-- arch/mips/kernel/cpu-bugs64.c | 47 +++++++++++++------------- arch/mips/kernel/setup.c | 4 ++- include/asm-mips/bugs.h | 25 ++++++++++++++ include/asm-mips/delay.h | 12 +++++-- include/asm-mips/war.h | 62 +++++++++++++++++++++++++++++++++++ 7 files changed, 148 insertions(+), 30 deletions(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 12bf96334174..11bc17ce0ebf 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -91,6 +91,9 @@ config MACH_DECSTATION select BOOT_ELF32 select CEVT_R4K select CSRC_R4K + select CPU_DADDI_WORKAROUNDS if 64BIT + select CPU_R4000_WORKAROUNDS if 64BIT + select CPU_R4400_WORKAROUNDS if 64BIT select DMA_NONCOHERENT select NO_IOPORT select IRQ_CPU @@ -1605,6 +1608,19 @@ config CPU_HAS_SYNC config GENERIC_CLOCKEVENTS_BROADCAST bool +# +# CPU non-features +# +config CPU_DADDI_WORKAROUNDS + bool + +config CPU_R4000_WORKAROUNDS + bool + select CPU_R4400_WORKAROUNDS + +config CPU_R4400_WORKAROUNDS + bool + # # Use the generic interrupt handling code in kernel/irq/: # diff --git a/arch/mips/Makefile b/arch/mips/Makefile index a1f8d8b96b03..a49127af33c8 100644 --- a/arch/mips/Makefile +++ b/arch/mips/Makefile @@ -141,6 +141,10 @@ cflags-$(CONFIG_CPU_R8000) += -march=r8000 -Wa,--trap cflags-$(CONFIG_CPU_R10000) += $(call cc-option,-march=r10000,-march=r8000) \ -Wa,--trap +cflags-$(CONFIG_CPU_R4000_WORKAROUNDS) += $(call cc-option,-mfix-r4000,) +cflags-$(CONFIG_CPU_R4400_WORKAROUNDS) += $(call cc-option,-mfix-r4400,) +cflags-$(CONFIG_CPU_DADDI_WORKAROUNDS) += $(call cc-option,-mno-daddi,) + ifdef CONFIG_CPU_SB1 ifdef CONFIG_SB1_PASS_1_WORKAROUNDS MODFLAGS += -msb1-pass1-workarounds @@ -602,9 +606,11 @@ ifdef CONFIG_64BIT endif endif - ifeq ($(KBUILD_SYM32), y) - ifeq ($(call cc-option-yn,-msym32), y) - cflags-y += -msym32 -DKBUILD_64BIT_SYM32 + ifeq ($(KBUILD_SYM32)$(call cc-option-yn,-msym32), yy) + cflags-y += -msym32 -DKBUILD_64BIT_SYM32 + else + ifeq ($(CONFIG_CPU_DADDI_WORKAROUNDS), y) + $(error CONFIG_CPU_DADDI_WORKAROUNDS unsupported without -msym32) endif endif endif diff --git a/arch/mips/kernel/cpu-bugs64.c b/arch/mips/kernel/cpu-bugs64.c index af78456d4138..417bb3e336ac 100644 --- a/arch/mips/kernel/cpu-bugs64.c +++ b/arch/mips/kernel/cpu-bugs64.c @@ -18,6 +18,15 @@ #include #include +static char bug64hit[] __initdata = + "reliable operation impossible!\n%s"; +static char nowar[] __initdata = + "Please report to ."; +static char r4kwar[] __initdata = + "Enable CPU_R4000_WORKAROUNDS to rectify."; +static char daddiwar[] __initdata = + "Enable CPU_DADDI_WORKAROUNDS to rectify."; + static inline void align_mod(const int align, const int mod) { asm volatile( @@ -155,13 +164,7 @@ static inline void check_mult_sh(void) } printk("no.\n"); - panic("Reliable operation impossible!\n" -#ifndef CONFIG_CPU_R4000 - "Configure for R4000 to enable the workaround." -#else - "Please report to ." -#endif - ); + panic(bug64hit, !R4000_WAR ? r4kwar : nowar); } static volatile int daddi_ov __initdata = 0; @@ -233,15 +236,11 @@ static inline void check_daddi(void) } printk("no.\n"); - panic("Reliable operation impossible!\n" -#if !defined(CONFIG_CPU_R4000) && !defined(CONFIG_CPU_R4400) - "Configure for R4000 or R4400 to enable the workaround." -#else - "Please report to ." -#endif - ); + panic(bug64hit, !DADDI_WAR ? daddiwar : nowar); } +int daddiu_bug __initdata = -1; + static inline void check_daddiu(void) { long v, w, tmp; @@ -281,7 +280,9 @@ static inline void check_daddiu(void) : "=&r" (v), "=&r" (w), "=&r" (tmp) : "I" (0xffffffffffffdb9aUL), "I" (0x1234)); - if (v == w) { + daddiu_bug = v != w; + + if (!daddiu_bug) { printk("no.\n"); return; } @@ -303,18 +304,16 @@ static inline void check_daddiu(void) } printk("no.\n"); - panic("Reliable operation impossible!\n" -#if !defined(CONFIG_CPU_R4000) && !defined(CONFIG_CPU_R4400) - "Configure for R4000 or R4400 to enable the workaround." -#else - "Please report to ." -#endif - ); + panic(bug64hit, !DADDI_WAR ? daddiwar : nowar); } -void __init check_bugs64(void) +void __init check_bugs64_early(void) { check_mult_sh(); - check_daddi(); check_daddiu(); } + +void __init check_bugs64(void) +{ + check_daddi(); +} diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c index f8a535afce39..7b4418dd5857 100644 --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -8,7 +8,7 @@ * Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 01, 02, 03 Ralf Baechle * Copyright (C) 1996 Stoned Elipot * Copyright (C) 1999 Silicon Graphics, Inc. - * Copyright (C) 2000 2001, 2002 Maciej W. Rozycki + * Copyright (C) 2000, 2001, 2002, 2007 Maciej W. Rozycki */ #include #include @@ -24,6 +24,7 @@ #include #include +#include #include #include #include @@ -561,6 +562,7 @@ void __init setup_arch(char **cmdline_p) } #endif cpu_report(); + check_bugs_early(); #if defined(CONFIG_VT) #if defined(CONFIG_VGA_CONSOLE) diff --git a/include/asm-mips/bugs.h b/include/asm-mips/bugs.h index 0d7f9c1f5546..9dc10df32078 100644 --- a/include/asm-mips/bugs.h +++ b/include/asm-mips/bugs.h @@ -1,19 +1,34 @@ /* * This is included by init/main.c to check for architecture-dependent bugs. * + * Copyright (C) 2007 Maciej W. Rozycki + * * Needs: * void check_bugs(void); */ #ifndef _ASM_BUGS_H #define _ASM_BUGS_H +#include #include + #include #include +extern int daddiu_bug; + +extern void check_bugs64_early(void); + extern void check_bugs32(void); extern void check_bugs64(void); +static inline void check_bugs_early(void) +{ +#ifdef CONFIG_64BIT + check_bugs64_early(); +#endif +} + static inline void check_bugs(void) { unsigned int cpu = smp_processor_id(); @@ -25,4 +40,14 @@ static inline void check_bugs(void) #endif } +static inline int r4k_daddiu_bug(void) +{ +#ifdef CONFIG_64BIT + WARN_ON(daddiu_bug < 0); + return daddiu_bug != 0; +#else + return 0; +#endif +} + #endif /* _ASM_BUGS_H */ diff --git a/include/asm-mips/delay.h b/include/asm-mips/delay.h index fab32131e9b4..de5105d05f1e 100644 --- a/include/asm-mips/delay.h +++ b/include/asm-mips/delay.h @@ -6,13 +6,16 @@ * Copyright (C) 1994 by Waldorf Electronics * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle * Copyright (C) 1999, 2000 Silicon Graphics, Inc. + * Copyright (C) 2007 Maciej W. Rozycki */ #ifndef _ASM_DELAY_H #define _ASM_DELAY_H #include #include + #include +#include static inline void __delay(unsigned long loops) { @@ -50,7 +53,7 @@ static inline void __delay(unsigned long loops) static inline void __udelay(unsigned long usecs, unsigned long lpj) { - unsigned long lo; + unsigned long hi, lo; /* * The rates of 128 is rounded wrongly by the catchall case @@ -70,11 +73,16 @@ static inline void __udelay(unsigned long usecs, unsigned long lpj) : "=h" (usecs), "=l" (lo) : "r" (usecs), "r" (lpj) : GCC_REG_ACCUM); - else if (sizeof(long) == 8) + else if (sizeof(long) == 8 && !R4000_WAR) __asm__("dmultu\t%2, %3" : "=h" (usecs), "=l" (lo) : "r" (usecs), "r" (lpj) : GCC_REG_ACCUM); + else if (sizeof(long) == 8 && R4000_WAR) + __asm__("dmultu\t%3, %4\n\tmfhi\t%0" + : "=r" (usecs), "=h" (hi), "=l" (lo) + : "r" (usecs), "r" (lpj) + : GCC_REG_ACCUM); __delay(usecs); } diff --git a/include/asm-mips/war.h b/include/asm-mips/war.h index d2808edfd4e9..22361d5e3bf0 100644 --- a/include/asm-mips/war.h +++ b/include/asm-mips/war.h @@ -4,12 +4,74 @@ * for more details. * * Copyright (C) 2002, 2004, 2007 by Ralf Baechle + * Copyright (C) 2007 Maciej W. Rozycki */ #ifndef _ASM_WAR_H #define _ASM_WAR_H #include +/* + * Work around certain R4000 CPU errata (as implemented by GCC): + * + * - A double-word or a variable shift may give an incorrect result + * if executed immediately after starting an integer division: + * "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", + * erratum #28 + * "MIPS R4000MC Errata, Processor Revision 2.2 and 3.0", erratum + * #19 + * + * - A double-word or a variable shift may give an incorrect result + * if executed while an integer multiplication is in progress: + * "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", + * errata #16 & #28 + * + * - An integer division may give an incorrect result if started in + * a delay slot of a taken branch or a jump: + * "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", + * erratum #52 + */ +#ifdef CONFIG_CPU_R4000_WORKAROUNDS +#define R4000_WAR 1 +#else +#define R4000_WAR 0 +#endif + +/* + * Work around certain R4400 CPU errata (as implemented by GCC): + * + * - A double-word or a variable shift may give an incorrect result + * if executed immediately after starting an integer division: + * "MIPS R4400MC Errata, Processor Revision 1.0", erratum #10 + * "MIPS R4400MC Errata, Processor Revision 2.0 & 3.0", erratum #4 + */ +#ifdef CONFIG_CPU_R4400_WORKAROUNDS +#define R4400_WAR 1 +#else +#define R4400_WAR 0 +#endif + +/* + * Work around the "daddi" and "daddiu" CPU errata: + * + * - The `daddi' instruction fails to trap on overflow. + * "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", + * erratum #23 + * + * - The `daddiu' instruction can produce an incorrect result. + * "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", + * erratum #41 + * "MIPS R4000MC Errata, Processor Revision 2.2 and 3.0", erratum + * #15 + * "MIPS R4400PC/SC Errata, Processor Revision 1.0", erratum #7 + * "MIPS R4400MC Errata, Processor Revision 1.0", erratum #5 + */ +#ifdef CONFIG_CPU_DADDI_WORKAROUNDS +#define DADDI_WAR 1 +#else +#define DADDI_WAR 0 +#endif + /* * Another R4600 erratum. Due to the lack of errata information the exact * technical details aren't known. I've experimentally found that disabling -- GitLab