/*
* Copyright (C) 2003, 2004 Maciej W. Rozycki
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/stddef.h>
#include <asm/bugs.h>
#include <asm/compiler.h>
#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/system.h>
static inline void align_mod(const int align, const int mod)
{
asm volatile(
".set push\n\t"
".set noreorder\n\t"
".balign %0\n\t"
".rept %1\n\t"
"nop\n\t"
".endr\n\t"
".set pop"
:
: "n" (align), "n" (mod));
}
static inline void mult_sh_align_mod(long *v1, long *v2, long *w,
const int align, const int mod)
{
unsigned long flags;
int m1, m2;
long p, s, lv1, lv2, lw;
/*
* We want the multiply and the shift to be isolated from the
* rest of the code to disable gcc optimizations. Hence the
* asm statements that execute nothing, but make gcc not know
* what the values of m1, m2 and s are and what lv2 and p are
* used for.
*/
local_irq_save(flags);
/*
* The following code leads to a wrong result of the first
* dsll32 when executed on R4000 rev. 2.2 or 3.0 (PRId
* 00000422 or 00000430, respectively).
*
* See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and
* 3.0" by MIPS Technologies, Inc., errata #16 and #28 for
* details. I got no permission to duplicate them here,
* sigh... --macro
*/
asm volatile(
""
: "=r" (m1), "=r" (m2), "=r" (s)
: "0" (5), "1" (8), "2" (5));
align_mod(align, mod);
/*
* The trailing nop is needed to fullfill the two-instruction
* requirement between reading hi/lo and staring a mult/div.
* Leaving it out may cause gas insert a nop itself breaking
* the desired alignment of the next chunk.
*/
asm volatile(
".set push\n\t"
".set noat\n\t"
".set noreorder\n\t"
".set nomacro\n\t"
"mult %2, %3\n\t"
"dsll32 %0, %4, %5\n\t"
"mflo $0\n\t"
"dsll32 %1, %4, %5\n\t"
"nop\n\t"
".set pop"
: "=&r" (lv1), "=r" (lw)
: "r" (m1), "r" (m2), "r" (s), "I" (0)
: "hi", "lo", GCC_REG_ACCUM);
/* We have to use single integers for m1 and m2 and a double
* one for p to be sure the mulsidi3 gcc's RTL multiplication
* instruction has the workaround applied. Older versions of
* gcc have correct umulsi3 and mulsi3, but other
* multiplication variants lack the workaround.
*/
asm volatile(
""
: "=r" (m1), "=r" (m2), "=r" (s)
: "0" (m1), "1" (m2), "2" (s));
align_mod(align, mod);
p = m1 * m2;
lv2 = s << 32;
asm volatile(
""
: "=r" (lv2)
: "0" (lv2), "r" (p));
local_irq_restore(flags);
*v1 = lv1;
*v2 = lv2;
*w = lw;
}
static inline void check_mult_sh(void)
{
long v1[8], v2[8], w[8];
int bug, fix, i;
printk("Checking for the multiply/shift bug... ");
/*
* Testing discovered false negatives for certain code offsets
* into cache lines. Hence we test all possible offsets for
* the worst assumption of an R4000 I-cache line width of 32
* bytes.
*
* We can't use a loop as alignment directives need to be
* immediates.
*/
mult_sh_align_mod(&v1[0], &v2[0], &w[0], 32, 0);
mult_sh_align_mod(&v1[1], &v2[1], &w[1], 32, 1);
mult_sh_align_mod(&v1[2], &v2[2], &w[2], 32, 2);
mult_sh_align_mod(&v1[3], &v2[3], &w[3], 32, 3);
mult_sh_align_mod(&v1[4], &v2[4], &w[4], 32, 4);
mult_sh_align_mod(&v1[5], &v2[5], &w[5], 32, 5);
mult_sh_align_mod(&v1[6], &v2[6], &w[6], 32, 6);
mult_sh_align_mod(&v1[7], &v2[7], &w[7], 32, 7);
bug = 0;
for (i = 0; i < 8; i++)
if (v1[i] != w[i])
bug = 1;
if (bug == 0) {
printk("no.\n");
return;
}
printk("yes, workaround... ");
fix = 1;
for (i = 0; i < 8; i++)
if (v2[i] != w[i])
fix = 0;
if (fix == 1) {
printk("yes.\n");
return;
}
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
);
}
static volatile int daddi_ov __initdata = 0;
asmlinkage void __init do_daddi_ov(struct pt_regs *regs)
{
daddi_ov = 1;
regs->cp0_epc += 4;
}
static inline void check_daddi(void)
{
extern asmlinkage void handle_daddi_ov(void);
unsigned long flags;
void *handler;
long v, tmp;
printk("Checking for the daddi bug... ");
local_irq_save(flags);
handler = set_except_vector(12, handle_daddi_ov);
/*
* The following code fails to trigger an overflow exception
* when executed on R4000 rev. 2.2 or 3.0 (PRId 00000422 or
* 00000430, respectively).
*
* See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and
* 3.0" by MIPS Technologies, Inc., erratum #23 for details.
* I got no permission to duplicate it here, sigh... --macro
*/
asm volatile(
".set push\n\t"
".set noat\n\t"
".set noreorder\n\t"
".set nomacro\n\t"
"addiu %1, $0, %2\n\t"
"dsrl %1, %1, 1\n\t"
#ifdef HAVE_AS_SET_DADDI
".set daddi\n\t"
#endif
"daddi %0, %1, %3\n\t"
".set pop"
: "=r" (v), "=&r" (tmp)
: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
set_except_vector(12, handler);
local_irq_restore(flags);
if (daddi_ov) {
printk("no.\n");
return;
}
printk("yes, workaround... ");
local_irq_save(flags);
handler = set_except_vector(12, handle_daddi_ov);
asm volatile(
"addiu %1, $0, %2\n\t"
"dsrl %1, %1, 1\n\t"
"daddi %0, %1, %3"
: "=r" (v), "=&r" (tmp)
: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
set_except_vector(12, handler);
local_irq_restore(flags);
if (daddi_ov) {
printk("yes.\n");
return;
}
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
);
}
static inline void check_daddiu(void)
{
long v, w, tmp;
printk("Checking for the daddiu bug... ");
/*
* The following code leads to a wrong result of daddiu when
* executed on R4400 rev. 1.0 (PRId 00000440).
*
* See "MIPS R4400PC/SC Errata, Processor Revision 1.0" by
* MIPS Technologies, Inc., erratum #7 for details.
*
* According to "MIPS R4000PC/SC Errata, Processor Revision
* 2.2 and 3.0" by MIPS Technologies, Inc., erratum #41 this
* problem affects R4000 rev. 2.2 and 3.0 (PRId 00000422 and
* 00000430, respectively), too. Testing failed to trigger it
* so far.
*
* I got no permission to duplicate the errata here, sigh...
* --macro
*/
asm volatile(
".set push\n\t"
".set noat\n\t"
".set noreorder\n\t"
".set nomacro\n\t"
"addiu %2, $0, %3\n\t"
"dsrl %2, %2, 1\n\t"
#ifdef HAVE_AS_SET_DADDI
".set daddi\n\t"
#endif
"daddiu %0, %2, %4\n\t"
"addiu %1, $0, %4\n\t"
"daddu %1, %2\n\t"
".set pop"
: "=&r" (v), "=&r" (w), "=&r" (tmp)
: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
if (v == w) {
printk("no.\n");
return;
}
printk("yes, workaround... ");
asm volatile(
"addiu %2, $0, %3\n\t"
"dsrl %2, %2, 1\n\t"
"daddiu %0, %2, %4\n\t"
"addiu %1, $0, %4\n\t"
"daddu %1, %2"
: "=&r" (v), "=&r" (w), "=&r" (tmp)
: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
if (v == w) {
printk("yes.\n");
return;
}
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
);
}
void __init check_bugs64(void)
{
check_mult_sh();
check_daddi();
check_daddiu();
}
