cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

vidtv_common.c (2510B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * The Virtual DVB test driver serves as a reference DVB driver and helps
      4 * validate the existing APIs in the media subsystem. It can also aid
      5 * developers working on userspace applications.
      6 *
      7 * Copyright (C) 2020 Daniel W. S. Almeida
      8 */
      9#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
     10
     11#include <linux/printk.h>
     12#include <linux/ratelimit.h>
     13#include <linux/string.h>
     14#include <linux/types.h>
     15
     16#include "vidtv_common.h"
     17
     18/**
     19 * vidtv_memcpy() - wrapper routine to be used by MPEG-TS
     20 *	generator, in order to avoid going past the
     21 *	output buffer.
     22 * @to:	Starting element to where a MPEG-TS packet will
     23 *	be copied.
     24 * @to_offset:	Starting position of the @to buffer to be filled.
     25 * @to_size:	Size of the @to buffer.
     26 * @from:	Starting element of the buffer to be copied.
     27 * @len:	Number of elements to be copy from @from buffer
     28 *	into @to+ @to_offset buffer.
     29 *
     30 * Note:
     31 *	Real digital TV demod drivers should not have memcpy
     32 *	wrappers. We use it here because emulating MPEG-TS
     33 *	generation at kernelspace requires some extra care.
     34 *
     35 * Return:
     36 *	Returns the number of bytes written
     37 */
     38u32 vidtv_memcpy(void *to,
     39		 size_t to_offset,
     40		 size_t to_size,
     41		 const void *from,
     42		 size_t len)
     43{
     44	if (unlikely(to_offset + len > to_size)) {
     45		pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
     46				   to_offset + len,
     47				   to_size);
     48		return 0;
     49	}
     50
     51	memcpy(to + to_offset, from, len);
     52	return len;
     53}
     54
     55/**
     56 * vidtv_memset() - wrapper routine to be used by MPEG-TS
     57 *	generator, in order to avoid going past the
     58 *	output buffer.
     59 * @to:	Starting element to set
     60 * @to_offset:	Starting position of the @to buffer to be filled.
     61 * @to_size:	Size of the @to buffer.
     62 * @c:		The value to set the memory to.
     63 * @len:	Number of elements to be copy from @from buffer
     64 *	into @to+ @to_offset buffer.
     65 *
     66 * Note:
     67 *	Real digital TV demod drivers should not have memset
     68 *	wrappers. We use it here because emulating MPEG-TS
     69 *	generation at kernelspace requires some extra care.
     70 *
     71 * Return:
     72 *	Returns the number of bytes written
     73 */
     74u32 vidtv_memset(void *to,
     75		 size_t to_offset,
     76		 size_t to_size,
     77		 const int c,
     78		 size_t len)
     79{
     80	if (unlikely(to_offset + len > to_size)) {
     81		pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
     82				   to_offset + len,
     83				   to_size);
     84		return 0;
     85	}
     86
     87	memset(to + to_offset, c, len);
     88	return len;
     89}