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

fncpy.h (2552B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/*
      3 * arch/arm/include/asm/fncpy.h - helper macros for function body copying
      4 *
      5 * Copyright (C) 2011 Linaro Limited
      6 */
      7
      8/*
      9 * These macros are intended for use when there is a need to copy a low-level
     10 * function body into special memory.
     11 *
     12 * For example, when reconfiguring the SDRAM controller, the code doing the
     13 * reconfiguration may need to run from SRAM.
     14 *
     15 * NOTE: that the copied function body must be entirely self-contained and
     16 * position-independent in order for this to work properly.
     17 *
     18 * NOTE: in order for embedded literals and data to get referenced correctly,
     19 * the alignment of functions must be preserved when copying.  To ensure this,
     20 * the source and destination addresses for fncpy() must be aligned to a
     21 * multiple of 8 bytes: you will be get a BUG() if this condition is not met.
     22 * You will typically need a ".align 3" directive in the assembler where the
     23 * function to be copied is defined, and ensure that your allocator for the
     24 * destination buffer returns 8-byte-aligned pointers.
     25 *
     26 * Typical usage example:
     27 *
     28 * extern int f(args);
     29 * extern uint32_t size_of_f;
     30 * int (*copied_f)(args);
     31 * void *sram_buffer;
     32 *
     33 * copied_f = fncpy(sram_buffer, &f, size_of_f);
     34 *
     35 * ... later, call the function: ...
     36 *
     37 * copied_f(args);
     38 *
     39 * The size of the function to be copied can't be determined from C:
     40 * this must be determined by other means, such as adding assmbler directives
     41 * in the file where f is defined.
     42 */
     43
     44#ifndef __ASM_FNCPY_H
     45#define __ASM_FNCPY_H
     46
     47#include <linux/types.h>
     48#include <linux/string.h>
     49
     50#include <asm/bug.h>
     51#include <asm/cacheflush.h>
     52
     53/*
     54 * Minimum alignment requirement for the source and destination addresses
     55 * for function copying.
     56 */
     57#define FNCPY_ALIGN 8
     58
     59#define fncpy(dest_buf, funcp, size) ({					\
     60	uintptr_t __funcp_address;					\
     61	typeof(funcp) __result;						\
     62									\
     63	asm("" : "=r" (__funcp_address) : "0" (funcp));			\
     64									\
     65	/*								\
     66	 * Ensure alignment of source and destination addresses,	\
     67	 * disregarding the function's Thumb bit:			\
     68	 */								\
     69	BUG_ON((uintptr_t)(dest_buf) & (FNCPY_ALIGN - 1) ||		\
     70		(__funcp_address & ~(uintptr_t)1 & (FNCPY_ALIGN - 1)));	\
     71									\
     72	memcpy(dest_buf, (void const *)(__funcp_address & ~1), size);	\
     73	flush_icache_range((unsigned long)(dest_buf),			\
     74		(unsigned long)(dest_buf) + (size));			\
     75									\
     76	asm("" : "=r" (__result)					\
     77		: "0" ((uintptr_t)(dest_buf) | (__funcp_address & 1)));	\
     78									\
     79	__result;							\
     80})
     81
     82#endif /* !__ASM_FNCPY_H */