x86, 64-bit: Move kernel_thread to C (3bd95dfb) · Commits · EulixOS / Software / Kernel

arch/x86/kernel/entry_64.S

+3 −46

Original line number	Diff line number	Diff line
		@@ -1166,63 +1166,20 @@ bad_gs:
		jmp 2b
		.previous

		/*
		* Create a kernel thread.
		*
		* C extern interface:
		* extern long kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
		*
		* asm input arguments:
		* rdi: fn, rsi: arg, rdx: flags
		*/
		ENTRY(kernel_thread)
		CFI_STARTPROC
		FAKE_STACK_FRAME $child_rip
		SAVE_ALL

		# rdi: flags, rsi: usp, rdx: will be &pt_regs
		movq %rdx,%rdi
		orq kernel_thread_flags(%rip),%rdi
		movq $-1, %rsi
		movq %rsp, %rdx

		xorl %r8d,%r8d
		xorl %r9d,%r9d

		# clone now
		call do_fork
		movq %rax,RAX(%rsp)
		xorl %edi,%edi

		/*
		* It isn't worth to check for reschedule here,
		* so internally to the x86_64 port you can rely on kernel_thread()
		* not to reschedule the child before returning, this avoids the need
		* of hacks for example to fork off the per-CPU idle tasks.
		* [Hopefully no generic code relies on the reschedule -AK]
		*/
		RESTORE_ALL
		UNFAKE_STACK_FRAME
		ret
		CFI_ENDPROC
		END(kernel_thread)

		ENTRY(child_rip)
		ENTRY(kernel_thread_helper)
		pushq $0 # fake return address
		CFI_STARTPROC
		/*
		* Here we are in the child and the registers are set as they were
		* at kernel_thread() invocation in the parent.
		*/
		movq %rdi, %rax
		movq %rsi, %rdi
		call *%rax
		call *%rsi
		# exit
		mov %eax, %edi
		call do_exit
		ud2 # padding for call trace
		CFI_ENDPROC
		END(child_rip)
		END(kernel_thread_helper)

		/*
		* execve(). This function needs to use IRET, not SYSRET, to set up all state properly.

+29 −2

Original line number	Diff line number	Diff line
		@@ -59,8 +59,6 @@ asmlinkage extern void ret_from_fork(void);
		DEFINE_PER_CPU(unsigned long, old_rsp);
		static DEFINE_PER_CPU(unsigned char, is_idle);

		unsigned long kernel_thread_flags = CLONE_VM \| CLONE_UNTRACED;

		static ATOMIC_NOTIFIER_HEAD(idle_notifier);

		void idle_notifier_register(struct notifier_block *n)
		@@ -231,6 +229,35 @@ void show_regs(struct pt_regs *regs)
		show_trace(NULL, regs, (void *)(regs + 1), regs->bp);
		}

		/*
		* This gets run with %si containing the
		* function to call, and %di containing
		* the "args".
		*/
		extern void kernel_thread_helper(void);

		/*
		* Create a kernel thread
		*/
		int kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
		{
		struct pt_regs regs;

		memset(&regs, 0, sizeof(regs));

		regs.si = (unsigned long) fn;
		regs.di = (unsigned long) arg;

		regs.orig_ax = -1;
		regs.ip = (unsigned long) kernel_thread_helper;
		regs.cs = __KERNEL_CS;
		regs.flags = X86_EFLAGS_IF;

		/* Ok, create the new process.. */
		return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, ~0UL, &regs, 0, NULL, NULL);
		}
		EXPORT_SYMBOL(kernel_thread);

		void release_thread(struct task_struct *dead_task)
		{
		if (dead_task->mm) {

+0 −2