mode_switch.h

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <stddef.h>
#include <stdint.h>
 
#if ENV_X86_64
int protected_mode_call_narg(uint32_t arg_count,
                             uint32_t func_ptr,
                             uint32_t opt_arg1,
                             uint32_t opt_arg2);
 
/*
 * Drops into protected mode and calls the function, which must have been compiled for x86_32.
 * After the function returns it enters long mode again.
 * The function pointer destination must be below 4GiB in physical memory.
 *
 * The called function doesn't have arguments and returns an int.
 */
static inline int protected_mode_call(void *func)
{
        return protected_mode_call_narg(0, (uintptr_t)func, 0, 0);
}
 
/*
 * Drops into protected mode and calls the function, which must have been compiled for x86_32.
 * After the function returns it enters long mode again.
 * The function pointer destination must be below 4GiB in physical memory.
 * Only the lower 32bits of the argument are passed to the called function.
 *
 * The called function have one argument and returns an int.
 */
static inline int protected_mode_call_1arg(void *func, uint32_t arg1)
{
        return protected_mode_call_narg(1, (uintptr_t)func, arg1, 0);
}
 
/*
 * Drops into protected mode and calls the function, which must have been compiled for x86_32.
 * After the function returns it enters long mode again.
 * The function pointer destination must be below 4GiB in physical memory.
 * Only the lower 32bits of the argument are passed to the called function.
 *
 * The called function has two arguments and returns an int.
 */
static inline int protected_mode_call_2arg(void *func, uint32_t arg1, uint32_t arg2)
{
        return protected_mode_call_narg(2, (uintptr_t)func, arg1, arg2);
}
#else
static inline int protected_mode_call(void *func)
{
        int (*doit)(void) = func;
 
        return doit();
}
 
static inline int protected_mode_call_1arg(void *func, uint32_t arg1)
{
        int (*doit)(uint32_t arg1) = func;
 
        return doit(arg1);
}
 
static inline int protected_mode_call_2arg(void *func, uint32_t arg1, uint32_t arg2)
{
        int (*doit)(uint32_t arg1, uint32_t arg2) = func;
 
        return doit(arg1, arg2);
}
#endif