/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_RUNTIME_CONST_H
#define _ASM_RUNTIME_CONST_H

#ifdef MODULE
  #error "Cannot use runtime-const infrastructure from modules"
#endif

#ifdef __ASSEMBLER__

.macro RUNTIME_CONST_PTR sym reg
        movq    $0x0123456789abcdef, %\reg
        1:
        .pushsection runtime_ptr_\sym, "a"
        .long   1b - 8 - .
        .popsection
.endm

#else /* __ASSEMBLER__ */

#define runtime_const_ptr(sym) ({                               \
        typeof(sym) __ret;                                      \
        asm_inline("mov %1,%0\n1:\n"                            \
                ".pushsection runtime_ptr_" #sym ",\"a\"\n\t"   \
                ".long 1b - %c2 - .\n"                          \
                ".popsection"                                   \
                :"=r" (__ret)                                   \
                :"i" ((unsigned long)0x0123456789abcdefull),    \
                 "i" (sizeof(long)));                           \
        __ret; })

// The 'typeof' will create at _least_ a 32-bit type, but
// will happily also take a bigger type and the 'shrl' will
// clear the upper bits
#define runtime_const_shift_right_32(val, sym) ({               \
        typeof(0u+(val)) __ret = (val);                         \
        asm_inline("shrl $12,%k0\n1:\n"                         \
                ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
                ".long 1b - 1 - .\n"                            \
                ".popsection"                                   \
                :"+r" (__ret));                                 \
        __ret; })

#define runtime_const_init(type, sym) do {              \
        extern s32 __start_runtime_##type##_##sym[];    \
        extern s32 __stop_runtime_##type##_##sym[];     \
        runtime_const_fixup(__runtime_fixup_##type,     \
                (unsigned long)(sym),                   \
                __start_runtime_##type##_##sym,         \
                __stop_runtime_##type##_##sym);         \
} while (0)

/*
 * The text patching is trivial - you can only do this at init time,
 * when the text section hasn't been marked RO, and before the text
 * has ever been executed.
 */
static inline void __runtime_fixup_ptr(void *where, unsigned long val)
{
        *(unsigned long *)where = val;
}

static inline void __runtime_fixup_shift(void *where, unsigned long val)
{
        *(unsigned char *)where = val;
}

static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
        unsigned long val, s32 *start, s32 *end)
{
        while (start < end) {
                fn(*start + (void *)start, val);
                start++;
        }
}

#endif /* __ASSEMBLER__ */
#endif