USB: serial: option: reimplement interface masking
[linux/fpc-iii.git] / arch / arm / include / asm / fncpy.h
blobde53547469246f063b5eaadc12ebc636041f2c28
1 /*
2 * arch/arm/include/asm/fncpy.h - helper macros for function body copying
4 * Copyright (C) 2011 Linaro Limited
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * These macros are intended for use when there is a need to copy a low-level
22 * function body into special memory.
24 * For example, when reconfiguring the SDRAM controller, the code doing the
25 * reconfiguration may need to run from SRAM.
27 * NOTE: that the copied function body must be entirely self-contained and
28 * position-independent in order for this to work properly.
30 * NOTE: in order for embedded literals and data to get referenced correctly,
31 * the alignment of functions must be preserved when copying. To ensure this,
32 * the source and destination addresses for fncpy() must be aligned to a
33 * multiple of 8 bytes: you will be get a BUG() if this condition is not met.
34 * You will typically need a ".align 3" directive in the assembler where the
35 * function to be copied is defined, and ensure that your allocator for the
36 * destination buffer returns 8-byte-aligned pointers.
38 * Typical usage example:
40 * extern int f(args);
41 * extern uint32_t size_of_f;
42 * int (*copied_f)(args);
43 * void *sram_buffer;
45 * copied_f = fncpy(sram_buffer, &f, size_of_f);
47 * ... later, call the function: ...
49 * copied_f(args);
51 * The size of the function to be copied can't be determined from C:
52 * this must be determined by other means, such as adding assmbler directives
53 * in the file where f is defined.
56 #ifndef __ASM_FNCPY_H
57 #define __ASM_FNCPY_H
59 #include <linux/types.h>
60 #include <linux/string.h>
62 #include <asm/bug.h>
63 #include <asm/cacheflush.h>
66 * Minimum alignment requirement for the source and destination addresses
67 * for function copying.
69 #define FNCPY_ALIGN 8
71 #define fncpy(dest_buf, funcp, size) ({ \
72 uintptr_t __funcp_address; \
73 typeof(funcp) __result; \
75 asm("" : "=r" (__funcp_address) : "0" (funcp)); \
77 /* \
78 * Ensure alignment of source and destination addresses, \
79 * disregarding the function's Thumb bit: \
80 */ \
81 BUG_ON((uintptr_t)(dest_buf) & (FNCPY_ALIGN - 1) || \
82 (__funcp_address & ~(uintptr_t)1 & (FNCPY_ALIGN - 1))); \
84 memcpy(dest_buf, (void const *)(__funcp_address & ~1), size); \
85 flush_icache_range((unsigned long)(dest_buf), \
86 (unsigned long)(dest_buf) + (size)); \
88 asm("" : "=r" (__result) \
89 : "0" ((uintptr_t)(dest_buf) | (__funcp_address & 1))); \
91 __result; \
94 #endif /* !__ASM_FNCPY_H */