1 files changed, 322 insertions, 0 deletions
diff --git a/arch/mips/kernel/r4k-bugs64.c b/arch/mips/kernel/r4k-bugs64.c
new file mode 100644
index 000000000000..1ff19f1ea5ca
--- /dev/null
+++ b/arch/mips/kernel/r4k-bugs64.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2003, 2004, 2007  Maciej W. Rozycki
+ */
+#include <linux/context_tracking.h>
+#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/setup.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 __always_inline __init
+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 __always_inline __init
+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", "$0");
+	/* 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 __always_inline __init 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) {
+		pr_cont("no.\n");
+		return;
+	}
+
+	pr_cont("yes, workaround... ");
+
+	fix = 1;
+	for (i = 0; i < 8; i++)
+		if (v2[i] != w[i])
+			fix = 0;
+
+	if (fix == 1) {
+		pr_cont("yes.\n");
+		return;
+	}
+
+	pr_cont("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 __init 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(EXCCODE_OV, 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(EXCCODE_OV, handler);
+	local_irq_restore(flags);
+
+	if (daddi_ov) {
+		pr_cont("no.\n");
+		return;
+	}
+
+	pr_cont("yes, workaround... ");
+
+	local_irq_save(flags);
+	handler = set_except_vector(EXCCODE_OV, 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(EXCCODE_OV, handler);
+	local_irq_restore(flags);
+
+	if (daddi_ov) {
+		pr_cont("yes.\n");
+		return;
+	}
+
+	pr_cont("no.\n");
+	panic(bug64hit, !DADDI_WAR ? daddiwar : nowar);
+}
+
+int daddiu_bug	= -1;
+
+static __init 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) {
+		pr_cont("no.\n");
+		return;
+	}
+
+	pr_cont("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) {
+		pr_cont("yes.\n");
+		return;
+	}
+
+	pr_cont("no.\n");
+	panic(bug64hit, !DADDI_WAR ? daddiwar : nowar);
+}
+
+void __init check_bugs64_early(void)
+{
+	check_mult_sh();
+	check_daddiu();
+}
+
+void __init check_bugs64(void)
+{
+	check_daddi();
+}