1 files changed, 131 insertions, 0 deletions
diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
new file mode 100644
index 000000000..898e9c78a
--- /dev/null
+++ b/arch/arm/include/asm/div64.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ARM_DIV64
+#define __ASM_ARM_DIV64
+
+#include <linux/types.h>
+#include <asm/compiler.h>
+
+/*
+ * The semantics of __div64_32() are:
+ *
+ * uint32_t __div64_32(uint64_t *n, uint32_t base)
+ * {
+ * 	uint32_t remainder = *n % base;
+ * 	*n = *n / base;
+ * 	return remainder;
+ * }
+ *
+ * In other words, a 64-bit dividend with a 32-bit divisor producing
+ * a 64-bit result and a 32-bit remainder.  To accomplish this optimally
+ * we override the generic version in lib/div64.c to call our __do_div64
+ * assembly implementation with completely non standard calling convention
+ * for arguments and results (beware).
+ */
+
+#ifdef __ARMEB__
+#define __xh "r0"
+#define __xl "r1"
+#else
+#define __xl "r0"
+#define __xh "r1"
+#endif
+
+static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
+{
+	register unsigned int __base      asm("r4") = base;
+	register unsigned long long __n   asm("r0") = *n;
+	register unsigned long long __res asm("r2");
+	register unsigned int __rem       asm(__xh);
+	asm(	__asmeq("%0", __xh)
+		__asmeq("%1", "r2")
+		__asmeq("%2", "r0")
+		__asmeq("%3", "r4")
+		"bl	__do_div64"
+		: "=r" (__rem), "=r" (__res)
+		: "r" (__n), "r" (__base)
+		: "ip", "lr", "cc");
+	*n = __res;
+	return __rem;
+}
+#define __div64_32 __div64_32
+
+#if !defined(CONFIG_AEABI)
+
+/*
+ * In OABI configurations, some uses of the do_div function
+ * cause gcc to run out of registers. To work around that,
+ * we can force the use of the out-of-line version for
+ * configurations that build a OABI kernel.
+ */
+#define do_div(n, base) __div64_32(&(n), base)
+
+#else
+
+/*
+ * gcc versions earlier than 4.0 are simply too problematic for the
+ * __div64_const32() code in asm-generic/div64.h. First there is
+ * gcc PR 15089 that tend to trig on more complex constructs, spurious
+ * .global __udivsi3 are inserted even if none of those symbols are
+ * referenced in the generated code, and those gcc versions are not able
+ * to do constant propagation on long long values anyway.
+ */
+
+#define __div64_const32_is_OK (__GNUC__ >= 4)
+
+static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
+{
+	unsigned long long res;
+	register unsigned int tmp asm("ip") = 0;
+
+	if (!bias) {
+		asm (	"umull	%Q0, %R0, %Q1, %Q2\n\t"
+			"mov	%Q0, #0"
+			: "=&r" (res)
+			: "r" (m), "r" (n)
+			: "cc");
+	} else if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
+		res = m;
+		asm (	"umlal	%Q0, %R0, %Q1, %Q2\n\t"
+			"mov	%Q0, #0"
+			: "+&r" (res)
+			: "r" (m), "r" (n)
+			: "cc");
+	} else {
+		asm (	"umull	%Q0, %R0, %Q2, %Q3\n\t"
+			"cmn	%Q0, %Q2\n\t"
+			"adcs	%R0, %R0, %R2\n\t"
+			"adc	%Q0, %1, #0"
+			: "=&r" (res), "+&r" (tmp)
+			: "r" (m), "r" (n)
+			: "cc");
+	}
+
+	if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
+		asm (	"umlal	%R0, %Q0, %R1, %Q2\n\t"
+			"umlal	%R0, %Q0, %Q1, %R2\n\t"
+			"mov	%R0, #0\n\t"
+			"umlal	%Q0, %R0, %R1, %R2"
+			: "+&r" (res)
+			: "r" (m), "r" (n)
+			: "cc");
+	} else {
+		asm (	"umlal	%R0, %Q0, %R2, %Q3\n\t"
+			"umlal	%R0, %1, %Q2, %R3\n\t"
+			"mov	%R0, #0\n\t"
+			"adds	%Q0, %1, %Q0\n\t"
+			"adc	%R0, %R0, #0\n\t"
+			"umlal	%Q0, %R0, %R2, %R3"
+			: "+&r" (res), "+&r" (tmp)
+			: "r" (m), "r" (n)
+			: "cc");
+	}
+
+	return res;
+}
+#define __arch_xprod_64 __arch_xprod_64
+
+#include <asm-generic/div64.h>
+
+#endif
+
+#endif