projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 373cd784 JH |
2 | /* |
| 3 | * safe read and write memory routines callable while atomic | |
| 4 | * | |
| 5 | * Copyright 2012 Imagination Technologies | |
| 6 | */ | |
| 7 | ||
| 8 | #include <linux/uaccess.h> | |
| 9 | #include <asm/io.h> | |
| 10 | ||
| 11 | /* | |
| 12 | * The generic probe_kernel_write() uses the user copy code which can split the | |
| 13 | * writes if the source is unaligned, and repeats writes to make exceptions | |
| 14 | * precise. We override it here to avoid these things happening to memory mapped | |
| 15 | * IO memory where they could have undesired effects. | |
| 16 | * Due to the use of CACHERD instruction this only works on Meta2 onwards. | |
| 17 | */ | |
| 18 | #ifdef CONFIG_METAG_META21 | |
| 19 | long probe_kernel_write(void *dst, const void *src, size_t size) | |
| 20 | { | |
| 21 | unsigned long ldst = (unsigned long)dst; | |
| 22 | void __iomem *iodst = (void __iomem *)dst; | |
| 23 | unsigned long lsrc = (unsigned long)src; | |
| 24 | const u8 *psrc = (u8 *)src; | |
| 25 | unsigned int pte, i; | |
| 26 | u8 bounce[8] __aligned(8); | |
| 27 | ||
| 28 | if (!size) | |
| 29 | return 0; | |
| 30 | ||
| 31 | /* Use the write combine bit to decide is the destination is MMIO. */ | |
| 32 | pte = __builtin_meta2_cacherd(dst); | |
| 33 | ||
| 34 | /* Check the mapping is valid and writeable. */ | |
| 35 | if ((pte & (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT)) | |
| 36 | != (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT)) | |
| 37 | return -EFAULT; | |
| 38 | ||
| 39 | /* Fall back to generic version for cases we're not interested in. */ | |
| 40 | if (pte & MMCU_ENTRY_WRC_BIT || /* write combined memory */ | |
| 41 | (ldst & (size - 1)) || /* destination unaligned */ | |
| 42 | size > 8 || /* more than max write size */ | |
| 43 | (size & (size - 1))) /* non power of 2 size */ | |
| 44 | return __probe_kernel_write(dst, src, size); | |
| 45 | ||
| 46 | /* If src is unaligned, copy to the aligned bounce buffer first. */ | |
| 47 | if (lsrc & (size - 1)) { | |
| 48 | for (i = 0; i < size; ++i) | |
| 49 | bounce[i] = psrc[i]; | |
| 50 | psrc = bounce; | |
| 51 | } | |
| 52 | ||
| 53 | switch (size) { | |
| 54 | case 1: | |
| 55 | writeb(*psrc, iodst); | |
| 56 | break; | |
| 57 | case 2: | |
| 58 | writew(*(const u16 *)psrc, iodst); | |
| 59 | break; | |
| 60 | case 4: | |
| 61 | writel(*(const u32 *)psrc, iodst); | |
| 62 | break; | |
| 63 | case 8: | |
| 64 | writeq(*(const u64 *)psrc, iodst); | |
| 65 | break; | |
| 66 | } | |
| 67 | return 0; | |
| 68 | } | |
| 69 | #endif |