kernel-ark/include/asm-mips/bugs.h
Maciej W. Rozycki 20d60d9973 [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>
2008-01-29 10:14:54 +00:00

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C

/*
* 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();
cpu_data[cpu].udelay_val = loops_per_jiffy;
check_bugs32();
#ifdef CONFIG_64BIT
check_bugs64();
#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 */