From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/mips/kernel/cmpxchg.c | 104 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 arch/mips/kernel/cmpxchg.c (limited to 'arch/mips/kernel/cmpxchg.c') diff --git a/arch/mips/kernel/cmpxchg.c b/arch/mips/kernel/cmpxchg.c new file mode 100644 index 000000000..e974a4954 --- /dev/null +++ b/arch/mips/kernel/cmpxchg.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Imagination Technologies + * Author: Paul Burton + */ + +#include +#include + +unsigned long __xchg_small(volatile void *ptr, unsigned long val, unsigned int size) +{ + u32 old32, new32, load32, mask; + volatile u32 *ptr32; + unsigned int shift; + + /* Check that ptr is naturally aligned */ + WARN_ON((unsigned long)ptr & (size - 1)); + + /* Mask value to the correct size. */ + mask = GENMASK((size * BITS_PER_BYTE) - 1, 0); + val &= mask; + + /* + * Calculate a shift & mask that correspond to the value we wish to + * exchange within the naturally aligned 4 byte integer that includes + * it. + */ + shift = (unsigned long)ptr & 0x3; + if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) + shift ^= sizeof(u32) - size; + shift *= BITS_PER_BYTE; + mask <<= shift; + + /* + * Calculate a pointer to the naturally aligned 4 byte integer that + * includes our byte of interest, and load its value. + */ + ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3); + load32 = *ptr32; + + do { + old32 = load32; + new32 = (load32 & ~mask) | (val << shift); + load32 = arch_cmpxchg(ptr32, old32, new32); + } while (load32 != old32); + + return (load32 & mask) >> shift; +} + +unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old, + unsigned long new, unsigned int size) +{ + u32 mask, old32, new32, load32, load; + volatile u32 *ptr32; + unsigned int shift; + + /* Check that ptr is naturally aligned */ + WARN_ON((unsigned long)ptr & (size - 1)); + + /* Mask inputs to the correct size. */ + mask = GENMASK((size * BITS_PER_BYTE) - 1, 0); + old &= mask; + new &= mask; + + /* + * Calculate a shift & mask that correspond to the value we wish to + * compare & exchange within the naturally aligned 4 byte integer + * that includes it. + */ + shift = (unsigned long)ptr & 0x3; + if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) + shift ^= sizeof(u32) - size; + shift *= BITS_PER_BYTE; + mask <<= shift; + + /* + * Calculate a pointer to the naturally aligned 4 byte integer that + * includes our byte of interest, and load its value. + */ + ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3); + load32 = *ptr32; + + while (true) { + /* + * Ensure the byte we want to exchange matches the expected + * old value, and if not then bail. + */ + load = (load32 & mask) >> shift; + if (load != old) + return load; + + /* + * Calculate the old & new values of the naturally aligned + * 4 byte integer that include the byte we want to exchange. + * Attempt to exchange the old value for the new value, and + * return if we succeed. + */ + old32 = (load32 & ~mask) | (old << shift); + new32 = (load32 & ~mask) | (new << shift); + load32 = arch_cmpxchg(ptr32, old32, new32); + if (load32 == old32) + return old; + } +} -- cgit v1.2.3