Commit 20d60d99 authored by Maciej W. Rozycki's avatar Maciej W. Rozycki Committed by Ralf Baechle
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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: default avatarMaciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 2b22c034

arch/mips/Kconfig

+16 −0
Original line number Diff line number Diff line
@@ -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/:

#

arch/mips/Makefile

+9 −3
Original line number Diff line number Diff line
@@ -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)

  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

arch/mips/kernel/cpu-bugs64.c

+23 −24
Original line number Diff line number Diff line
@@ -18,6 +18,15 @@ 
#include <asm/mipsregs.h>

#include <asm/system.h>



static char bug64hit[] __initdata =

	"reliable operation impossible!\n%s";

static char nowar[] __initdata =

	"Please report to <linux-mips@linux-mips.org>.";

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 <linux-mips@linux-mips.org>."

#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 <linux-mips@linux-mips.org>."

#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 <linux-mips@linux-mips.org>."

#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();

}

arch/mips/kernel/setup.c

+3 −1
Original line number Diff line number Diff line
@@ -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 <linux/init.h>

#include <linux/ioport.h>
@@ -24,6 +24,7 @@ 


#include <asm/addrspace.h>

#include <asm/bootinfo.h>

#include <asm/bugs.h>

#include <asm/cache.h>

#include <asm/cpu.h>

#include <asm/sections.h>
@@ -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)

include/asm-mips/bugs.h

+25 −0
Original line number Diff line number Diff line 
/*

 * 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 <linux/bug.h>

#include <linux/delay.h>



#include <asm/cpu.h>

#include <asm/cpu-info.h>



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 */

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