From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/mips/kernel/cpu-bugs64.c | 327 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 327 insertions(+) create mode 100644 arch/mips/kernel/cpu-bugs64.c (limited to 'arch/mips/kernel/cpu-bugs64.c') diff --git a/arch/mips/kernel/cpu-bugs64.c b/arch/mips/kernel/cpu-bugs64.c new file mode 100644 index 000000000..09f4034f2 --- /dev/null +++ b/arch/mips/kernel/cpu-bugs64.c @@ -0,0 +1,327 @@ +/* + * Copyright (C) 2003, 2004, 2007 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 +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +static char bug64hit[] __initdata = + "reliable operation impossible!\n%s"; +static char nowar[] __initdata = + "Please report to ."; +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( + ".set push\n\t" + ".set noreorder\n\t" + ".balign %0\n\t" + ".rept %1\n\t" + "nop\n\t" + ".endr\n\t" + ".set pop" + : + : GCC_IMM_ASM() (align), GCC_IMM_ASM() (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 fulfill 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(bug64hit, !R4000_WAR ? r4kwar : nowar); +} + +static volatile int daddi_ov; + +asmlinkage void __init do_daddi_ov(struct pt_regs *regs) +{ + enum ctx_state prev_state; + + prev_state = exception_enter(); + daddi_ov = 1; + regs->cp0_epc += 4; + exception_exit(prev_state); +} + +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(bug64hit, !DADDI_WAR ? daddiwar : nowar); +} + +int daddiu_bug = config_enabled(CONFIG_CPU_MIPSR6) ? 0 : -1; + +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)); + + daddiu_bug = v != w; + + if (!daddiu_bug) { + 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(bug64hit, !DADDI_WAR ? daddiwar : nowar); +} + +void __init check_bugs64_early(void) +{ + if (!config_enabled(CONFIG_CPU_MIPSR6)) { + check_mult_sh(); + check_daddiu(); + } +} + +void __init check_bugs64(void) +{ + if (!config_enabled(CONFIG_CPU_MIPSR6)) + check_daddi(); +} -- cgit v1.2.3-54-g00ecf