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[MIPS] R4000/R4400 errata workarounds

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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
2007-10-23 12:43:11 +01:00
committed by Ralf Baechle
parent 2b22c034d0
commit 20d60d9973
7 changed files with 148 additions and 30 deletions
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47
arch/mips/kernel/cpu-bugs64.c
View File

@@ -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_early(void)
{
check_mult_sh();
check_daddiu();
}
void __init check_bugs64(void)
{
check_mult_sh();
check_daddi();
check_daddiu();
}