/* 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; }