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 */

 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 */