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49d083bd72
Under certain arches (ARM) function pointers cannot be used naively. Specifically, for thumb functions, their 0 bit is set, but they are contained on a word aligned address. Add a fncpy macro to perform function copies correctly along with two helpers, fnptr_to_address, and fnptr_translate. Signed-off-by: Russ Dill <Russ.Dill@ti.com>
105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/*
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* include/asm-generic/fncpy.h - helper macros for function body copying
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*
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* Copyright (C) 2011 Linaro Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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* These macros are intended for use when there is a need to copy a low-level
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* function body into special memory.
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*
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* For example, when reconfiguring the SDRAM controller, the code doing the
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* reconfiguration may need to run from SRAM.
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*
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* NOTE: that the copied function body must be entirely self-contained and
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* position-independent in order for this to work properly.
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*
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* Typical usage example:
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*
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* extern int f(args);
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* extern uint32_t size_of_f;
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* int (*copied_f)(args);
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* void *sram_buffer;
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*
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* copied_f = fncpy(sram_buffer, &f, size_of_f);
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*
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* ... later, call the function: ...
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*
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* copied_f(args);
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*
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* The size of the function to be copied can't be determined from C:
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* this must be determined by other means, such as adding assmbler directives
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* in the file where f is defined.
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*/
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#ifndef __ASM_GENERIC_FNCPY_H
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#define __ASM_GENERIC_FNCPY_H
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#include <linux/types.h>
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#include <linux/string.h>
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#include <asm/bug.h>
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#include <asm/cacheflush.h>
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/*
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* Minimum alignment requirement for the source and destination addresses
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* for function copying.
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*/
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#ifndef ARCH_FNCPY_ALIGN
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#define ARCH_FNCPY_ALIGN 0
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#endif
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#define ARCH_FNCPY_MASK ((1 << (ARCH_FNCPY_ALIGN)) - 1)
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#ifndef fnptr_to_addr
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#define fnptr_to_addr(funcp) ({ \
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(uintptr_t) (funcp); \
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})
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#endif
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#ifndef fnptr_translate
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#define fnptr_translate(orig_funcp, new_addr) ({ \
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(typeof(orig_funcp)) (new_addr); \
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})
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#endif
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/* Ensure alignment of source and destination addresses */
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#ifndef fn_dest_invalid
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#define fn_dest_invalid(funcp, dest_buf) ({ \
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uintptr_t __funcp_address; \
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\
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__funcp_address = fnptr_to_addr(funcp); \
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\
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((uintptr_t)(dest_buf) & ARCH_FNCPY_MASK) || \
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(__funcp_address & ARCH_FNCPY_MASK); \
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})
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#endif
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#ifndef fncpy
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#define fncpy(dest_buf, funcp, size) ({ \
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BUG_ON(fn_dest_invalid(funcp, dest_buf)); \
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\
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memcpy(dest_buf, (void const *)(funcp), size); \
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flush_icache_range((unsigned long)(dest_buf), \
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(unsigned long)(dest_buf) + (size)); \
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\
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fnptr_translate(funcp, dest_buf); \
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})
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#endif
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#endif /* !__ASM_GENERIC_FNCPY_H */
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