cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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div64.h (2335B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef _ASM_X86_DIV64_H
      3#define _ASM_X86_DIV64_H
      4
      5#ifdef CONFIG_X86_32
      6
      7#include <linux/types.h>
      8#include <linux/log2.h>
      9
     10/*
     11 * do_div() is NOT a C function. It wants to return
     12 * two values (the quotient and the remainder), but
     13 * since that doesn't work very well in C, what it
     14 * does is:
     15 *
     16 * - modifies the 64-bit dividend _in_place_
     17 * - returns the 32-bit remainder
     18 *
     19 * This ends up being the most efficient "calling
     20 * convention" on x86.
     21 */
     22#define do_div(n, base)						\
     23({								\
     24	unsigned long __upper, __low, __high, __mod, __base;	\
     25	__base = (base);					\
     26	if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \
     27		__mod = n & (__base - 1);			\
     28		n >>= ilog2(__base);				\
     29	} else {						\
     30		asm("" : "=a" (__low), "=d" (__high) : "A" (n));\
     31		__upper = __high;				\
     32		if (__high) {					\
     33			__upper = __high % (__base);		\
     34			__high = __high / (__base);		\
     35		}						\
     36		asm("divl %2" : "=a" (__low), "=d" (__mod)	\
     37			: "rm" (__base), "0" (__low), "1" (__upper));	\
     38		asm("" : "=A" (n) : "a" (__low), "d" (__high));	\
     39	}							\
     40	__mod;							\
     41})
     42
     43static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
     44{
     45	union {
     46		u64 v64;
     47		u32 v32[2];
     48	} d = { dividend };
     49	u32 upper;
     50
     51	upper = d.v32[1];
     52	d.v32[1] = 0;
     53	if (upper >= divisor) {
     54		d.v32[1] = upper / divisor;
     55		upper %= divisor;
     56	}
     57	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
     58		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
     59	return d.v64;
     60}
     61#define div_u64_rem	div_u64_rem
     62
     63static inline u64 mul_u32_u32(u32 a, u32 b)
     64{
     65	u32 high, low;
     66
     67	asm ("mull %[b]" : "=a" (low), "=d" (high)
     68			 : [a] "a" (a), [b] "rm" (b) );
     69
     70	return low | ((u64)high) << 32;
     71}
     72#define mul_u32_u32 mul_u32_u32
     73
     74#else
     75# include <asm-generic/div64.h>
     76
     77/*
     78 * Will generate an #DE when the result doesn't fit u64, could fix with an
     79 * __ex_table[] entry when it becomes an issue.
     80 */
     81static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div)
     82{
     83	u64 q;
     84
     85	asm ("mulq %2; divq %3" : "=a" (q)
     86				: "a" (a), "rm" (mul), "rm" (div)
     87				: "rdx");
     88
     89	return q;
     90}
     91#define mul_u64_u64_div_u64 mul_u64_u64_div_u64
     92
     93static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
     94{
     95	return mul_u64_u64_div_u64(a, mul, div);
     96}
     97#define mul_u64_u32_div	mul_u64_u32_div
     98
     99#endif /* CONFIG_X86_32 */
    100
    101#endif /* _ASM_X86_DIV64_H */