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/* SPDX-License-Identifier: GPL-2.0-only */
#include <thread.h>
#if ENV_X86_64
#error COOP_MULTITASKING does not currently support x86_64
#endif
/* The stack frame looks like the following after a pushad instruction. */
struct pushad_regs {
uint32_t edi; /* Offset 0x00 */
uint32_t esi; /* Offset 0x04 */
uint32_t ebp; /* Offset 0x08 */
uint32_t esp; /* Offset 0x0c */
uint32_t ebx; /* Offset 0x10 */
uint32_t edx; /* Offset 0x14 */
uint32_t ecx; /* Offset 0x18 */
uint32_t eax; /* Offset 0x1c */
};
static inline uintptr_t push_stack(uintptr_t cur_stack, uintptr_t value)
{
uintptr_t *addr;
cur_stack -= sizeof(value);
addr = (uintptr_t *)cur_stack;
*addr = value;
return cur_stack;
}
void arch_prepare_thread(struct thread *t,
asmlinkage void (*thread_entry)(void *), void *arg)
{
uintptr_t stack = t->stack_current;
/* Imitate thread_entry(t) with return address of 0. thread_entry()
* is assumed to never return. */
stack = push_stack(stack, (uintptr_t)arg);
stack = push_stack(stack, (uintptr_t)0);
stack = push_stack(stack, (uintptr_t)thread_entry);
/* Make room for the registers. Ignore initial values. */
stack -= sizeof(struct pushad_regs);
t->stack_current = stack;
}
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