include/asm-generic/fncpy.h

   1 /*
   2  * include/asm-generic/fncpy.h - helper macros for function body copying
   3  *
   4  * Copyright (C) 2011 Linaro Limited
   5  *
   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.
   9  *
  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.
  14  *
  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
  18  */
  19
  20 /*
  21  * These macros are intended for use when there is a need to copy a low-level
  22  * function body into special memory.
  23  *
  24  * For example, when reconfiguring the SDRAM controller, the code doing the
  25  * reconfiguration may need to run from SRAM.
  26  *
  27  * NOTE: that the copied function body must be entirely self-contained and
  28  * position-independent in order for this to work properly.
  29  *
  30  * Typical usage example:
  31  *
  32  * extern int f(args);
  33  * extern uint32_t size_of_f;
  34  * int (*copied_f)(args);
  35  * void *sram_buffer;
  36  *
  37  * copied_f = fncpy(sram_buffer, &f, size_of_f);
  38  *
  39  * ... later, call the function: ...
  40  *
  41  * copied_f(args);
  42  *
  43  * The size of the function to be copied can't be determined from C:
  44  * this must be determined by other means, such as adding assmbler directives
  45  * in the file where f is defined.
  46  */
  47
  48 #ifndef __ASM_GENERIC_FNCPY_H
  49 #define __ASM_GENERIC_FNCPY_H
  50
  51 #include <linux/types.h>
  52 #include <linux/string.h>
  53
  54 #include <asm/bug.h>
  55 #include <asm/cacheflush.h>
  56
  57 /*
  58  * Minimum alignment requirement for the source and destination addresses
  59  * for function copying.
  60  */
  61 #ifndef ARCH_FNCPY_ALIGN
  62 #define ARCH_FNCPY_ALIGN        0
  63 #endif
  64
  65 #define ARCH_FNCPY_MASK         ((1 << (ARCH_FNCPY_ALIGN)) - 1)
  66
  67 #ifndef fnptr_to_addr
  68 #define fnptr_to_addr(funcp) ({                                         \
  69         (uintptr_t) (funcp);                                            \
  70 })
  71 #endif
  72
  73 #ifndef fnptr_translate
  74 #define fnptr_translate(orig_funcp, new_addr) ({                        \
  75         (typeof(orig_funcp)) (new_addr);                                \
  76 })
  77 #endif
  78
  79 /* Ensure alignment of source and destination addresses */
  80 #ifndef fn_dest_invalid
  81 #define fn_dest_invalid(funcp, dest_buf) ({                             \
  82         uintptr_t __funcp_address;                                      \
  83                                                                         \
  84         __funcp_address = fnptr_to_addr(funcp);                         \
  85                                                                         \
  86         ((uintptr_t)(dest_buf) & ARCH_FNCPY_MASK) ||                    \
  87                 (__funcp_address & ARCH_FNCPY_MASK);                    \
  88 })
  89 #endif
  90
  91 #ifndef fncpy
  92 #define fncpy(dest_buf, funcp, size) ({                                 \
  93         BUG_ON(fn_dest_invalid(funcp, dest_buf));                       \
  94                                                                         \
  95         memcpy(dest_buf, (void const *)(funcp), size);                  \
  96         flush_icache_range((unsigned long)(dest_buf),                   \
  97                 (unsigned long)(dest_buf) + (size));                    \
  98                                                                         \
  99         fnptr_translate(funcp, dest_buf);                               \
 100 })
 101 #endif
 102
 103 #endif /* !__ASM_GENERIC_FNCPY_H */
 104