326 lines
7.5 KiB
C
326 lines
7.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2003, 2004, 2007 Maciej W. Rozycki
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*/
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#include <linux/context_tracking.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/stddef.h>
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#include <asm/bugs.h>
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#include <asm/compiler.h>
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#include <asm/cpu.h>
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#include <asm/fpu.h>
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#include <asm/mipsregs.h>
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#include <asm/setup.h>
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static char bug64hit[] __initdata =
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"reliable operation impossible!\n%s";
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static char nowar[] __initdata =
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"Please report to <linux-mips@vger.kernel.org>.";
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static char r4kwar[] __initdata =
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"Enable CPU_R4000_WORKAROUNDS to rectify.";
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static char daddiwar[] __initdata =
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"Enable CPU_DADDI_WORKAROUNDS to rectify.";
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static __always_inline __init
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void align_mod(const int align, const int mod)
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{
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asm volatile(
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".set push\n\t"
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".set noreorder\n\t"
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".balign %0\n\t"
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".rept %1\n\t"
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"nop\n\t"
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".endr\n\t"
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".set pop"
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:
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: "n"(align), "n"(mod));
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}
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static __always_inline __init
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void mult_sh_align_mod(long *v1, long *v2, long *w,
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const int align, const int mod)
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{
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unsigned long flags;
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int m1, m2;
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long p, s, lv1, lv2, lw;
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/*
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* We want the multiply and the shift to be isolated from the
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* rest of the code to disable gcc optimizations. Hence the
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* asm statements that execute nothing, but make gcc not know
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* what the values of m1, m2 and s are and what lv2 and p are
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* used for.
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*/
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local_irq_save(flags);
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/*
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* The following code leads to a wrong result of the first
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* dsll32 when executed on R4000 rev. 2.2 or 3.0 (PRId
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* 00000422 or 00000430, respectively).
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*
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* See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and
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* 3.0" by MIPS Technologies, Inc., errata #16 and #28 for
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* details. I got no permission to duplicate them here,
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* sigh... --macro
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*/
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asm volatile(
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""
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: "=r" (m1), "=r" (m2), "=r" (s)
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: "0" (5), "1" (8), "2" (5));
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align_mod(align, mod);
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/*
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* The trailing nop is needed to fulfill the two-instruction
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* requirement between reading hi/lo and staring a mult/div.
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* Leaving it out may cause gas insert a nop itself breaking
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* the desired alignment of the next chunk.
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*/
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asm volatile(
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".set push\n\t"
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".set noat\n\t"
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".set noreorder\n\t"
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".set nomacro\n\t"
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"mult %2, %3\n\t"
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"dsll32 %0, %4, %5\n\t"
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"mflo $0\n\t"
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"dsll32 %1, %4, %5\n\t"
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"nop\n\t"
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".set pop"
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: "=&r" (lv1), "=r" (lw)
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: "r" (m1), "r" (m2), "r" (s), "I" (0)
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: "hi", "lo", "$0");
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/* We have to use single integers for m1 and m2 and a double
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* one for p to be sure the mulsidi3 gcc's RTL multiplication
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* instruction has the workaround applied. Older versions of
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* gcc have correct umulsi3 and mulsi3, but other
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* multiplication variants lack the workaround.
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*/
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asm volatile(
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""
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: "=r" (m1), "=r" (m2), "=r" (s)
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: "0" (m1), "1" (m2), "2" (s));
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align_mod(align, mod);
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p = m1 * m2;
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lv2 = s << 32;
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asm volatile(
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""
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: "=r" (lv2)
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: "0" (lv2), "r" (p));
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local_irq_restore(flags);
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*v1 = lv1;
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*v2 = lv2;
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*w = lw;
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}
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static __always_inline __init void check_mult_sh(void)
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{
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long v1[8], v2[8], w[8];
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int bug, fix, i;
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printk("Checking for the multiply/shift bug... ");
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/*
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* Testing discovered false negatives for certain code offsets
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* into cache lines. Hence we test all possible offsets for
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* the worst assumption of an R4000 I-cache line width of 32
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* bytes.
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*
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* We can't use a loop as alignment directives need to be
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* immediates.
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*/
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mult_sh_align_mod(&v1[0], &v2[0], &w[0], 32, 0);
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mult_sh_align_mod(&v1[1], &v2[1], &w[1], 32, 1);
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mult_sh_align_mod(&v1[2], &v2[2], &w[2], 32, 2);
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mult_sh_align_mod(&v1[3], &v2[3], &w[3], 32, 3);
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mult_sh_align_mod(&v1[4], &v2[4], &w[4], 32, 4);
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mult_sh_align_mod(&v1[5], &v2[5], &w[5], 32, 5);
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mult_sh_align_mod(&v1[6], &v2[6], &w[6], 32, 6);
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mult_sh_align_mod(&v1[7], &v2[7], &w[7], 32, 7);
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bug = 0;
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for (i = 0; i < 8; i++)
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if (v1[i] != w[i])
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bug = 1;
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if (bug == 0) {
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pr_cont("no.\n");
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return;
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}
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pr_cont("yes, workaround... ");
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fix = 1;
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for (i = 0; i < 8; i++)
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if (v2[i] != w[i])
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fix = 0;
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if (fix == 1) {
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pr_cont("yes.\n");
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return;
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}
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pr_cont("no.\n");
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panic(bug64hit,
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IS_ENABLED(CONFIG_CPU_R4000_WORKAROUNDS) ? nowar : r4kwar);
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}
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static volatile int daddi_ov;
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asmlinkage void __init do_daddi_ov(struct pt_regs *regs)
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{
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enum ctx_state prev_state;
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prev_state = exception_enter();
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daddi_ov = 1;
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regs->cp0_epc += 4;
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exception_exit(prev_state);
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}
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static __init void check_daddi(void)
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{
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extern asmlinkage void handle_daddi_ov(void);
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unsigned long flags;
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void *handler;
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long v, tmp;
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printk("Checking for the daddi bug... ");
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local_irq_save(flags);
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handler = set_except_vector(EXCCODE_OV, handle_daddi_ov);
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/*
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* The following code fails to trigger an overflow exception
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* when executed on R4000 rev. 2.2 or 3.0 (PRId 00000422 or
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* 00000430, respectively).
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*
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* See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and
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* 3.0" by MIPS Technologies, Inc., erratum #23 for details.
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* I got no permission to duplicate it here, sigh... --macro
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*/
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asm volatile(
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".set push\n\t"
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".set noat\n\t"
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".set noreorder\n\t"
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".set nomacro\n\t"
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"addiu %1, $0, %2\n\t"
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"dsrl %1, %1, 1\n\t"
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#ifdef HAVE_AS_SET_DADDI
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".set daddi\n\t"
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#endif
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"daddi %0, %1, %3\n\t"
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".set pop"
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: "=r" (v), "=&r" (tmp)
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: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
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set_except_vector(EXCCODE_OV, handler);
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local_irq_restore(flags);
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if (daddi_ov) {
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pr_cont("no.\n");
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return;
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}
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pr_cont("yes, workaround... ");
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local_irq_save(flags);
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handler = set_except_vector(EXCCODE_OV, handle_daddi_ov);
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asm volatile(
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"addiu %1, $0, %2\n\t"
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"dsrl %1, %1, 1\n\t"
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"daddi %0, %1, %3"
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: "=r" (v), "=&r" (tmp)
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: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
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set_except_vector(EXCCODE_OV, handler);
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local_irq_restore(flags);
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if (daddi_ov) {
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pr_cont("yes.\n");
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return;
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}
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pr_cont("no.\n");
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panic(bug64hit,
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IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS) ? nowar : daddiwar);
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}
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int daddiu_bug = -1;
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static __init void check_daddiu(void)
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{
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long v, w, tmp;
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printk("Checking for the daddiu bug... ");
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/*
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* The following code leads to a wrong result of daddiu when
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* executed on R4400 rev. 1.0 (PRId 00000440).
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*
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* See "MIPS R4400PC/SC Errata, Processor Revision 1.0" by
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* MIPS Technologies, Inc., erratum #7 for details.
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*
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* According to "MIPS R4000PC/SC Errata, Processor Revision
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* 2.2 and 3.0" by MIPS Technologies, Inc., erratum #41 this
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* problem affects R4000 rev. 2.2 and 3.0 (PRId 00000422 and
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* 00000430, respectively), too. Testing failed to trigger it
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* so far.
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*
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* I got no permission to duplicate the errata here, sigh...
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* --macro
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*/
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asm volatile(
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".set push\n\t"
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".set noat\n\t"
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".set noreorder\n\t"
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".set nomacro\n\t"
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"addiu %2, $0, %3\n\t"
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"dsrl %2, %2, 1\n\t"
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#ifdef HAVE_AS_SET_DADDI
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".set daddi\n\t"
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#endif
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"daddiu %0, %2, %4\n\t"
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"addiu %1, $0, %4\n\t"
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"daddu %1, %2\n\t"
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".set pop"
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: "=&r" (v), "=&r" (w), "=&r" (tmp)
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: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
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daddiu_bug = v != w;
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if (!daddiu_bug) {
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pr_cont("no.\n");
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return;
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}
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pr_cont("yes, workaround... ");
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asm volatile(
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"addiu %2, $0, %3\n\t"
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"dsrl %2, %2, 1\n\t"
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"daddiu %0, %2, %4\n\t"
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"addiu %1, $0, %4\n\t"
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"daddu %1, %2"
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: "=&r" (v), "=&r" (w), "=&r" (tmp)
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: "I" (0xffffffffffffdb9aUL), "I" (0x1234));
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if (v == w) {
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pr_cont("yes.\n");
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return;
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}
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pr_cont("no.\n");
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panic(bug64hit,
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IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS) ? nowar : daddiwar);
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}
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void __init check_bugs64_early(void)
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{
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check_mult_sh();
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check_daddiu();
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}
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void __init check_bugs64(void)
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{
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check_daddi();
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}
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