e3c92e8171
This implements the runtime constant infrastructure for x86, allowing the dcache d_hash() function to be generated using as a constant for hash table address followed by shift by a constant of the hash index. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_RUNTIME_CONST_H
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#define _ASM_RUNTIME_CONST_H
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#define runtime_const_ptr(sym) ({ \
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typeof(sym) __ret; \
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asm_inline("mov %1,%0\n1:\n" \
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".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
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".long 1b - %c2 - .\n\t" \
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".popsection" \
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:"=r" (__ret) \
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:"i" ((unsigned long)0x0123456789abcdefull), \
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"i" (sizeof(long))); \
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__ret; })
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// The 'typeof' will create at _least_ a 32-bit type, but
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// will happily also take a bigger type and the 'shrl' will
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// clear the upper bits
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#define runtime_const_shift_right_32(val, sym) ({ \
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typeof(0u+(val)) __ret = (val); \
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asm_inline("shrl $12,%k0\n1:\n" \
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".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
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".long 1b - 1 - .\n\t" \
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".popsection" \
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:"+r" (__ret)); \
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__ret; })
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#define runtime_const_init(type, sym) do { \
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extern s32 __start_runtime_##type##_##sym[]; \
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extern s32 __stop_runtime_##type##_##sym[]; \
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runtime_const_fixup(__runtime_fixup_##type, \
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(unsigned long)(sym), \
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__start_runtime_##type##_##sym, \
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__stop_runtime_##type##_##sym); \
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} while (0)
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/*
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* The text patching is trivial - you can only do this at init time,
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* when the text section hasn't been marked RO, and before the text
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* has ever been executed.
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*/
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static inline void __runtime_fixup_ptr(void *where, unsigned long val)
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{
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*(unsigned long *)where = val;
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}
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static inline void __runtime_fixup_shift(void *where, unsigned long val)
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{
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*(unsigned char *)where = val;
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}
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static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
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unsigned long val, s32 *start, s32 *end)
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{
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while (start < end) {
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fn(*start + (void *)start, val);
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start++;
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}
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}
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#endif
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