Commit bc067736 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc: Rearrange copy_thread child stack creation 



This makes it a bit clearer where the stack frame is created, and will
allow easier use of some of the stack offset constants in a later
change.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-5-npiggin@gmail.com
parent 32c52092

arch/powerpc/kernel/process.c

+6 −5
Original line number Diff line number Diff line
@@ -1755,13 +1755,16 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 


	klp_init_thread_info(p);



	/* Create initial stack frame. */

	sp -= (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD);

	((unsigned long *)sp)[0] = 0;



	/* Copy registers */

	sp -= sizeof(struct pt_regs);

	childregs = (struct pt_regs *) sp;

	childregs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);

	if (unlikely(args->fn)) {

		/* kernel thread */

		memset(childregs, 0, sizeof(struct pt_regs));

		childregs->gpr[1] = sp + sizeof(struct pt_regs);

		childregs->gpr[1] = sp + (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD);

		/* function */

		if (args->fn)

			childregs->gpr[14] = ppc_function_entry((void *)args->fn);
@@ -1796,7 +1799,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 
			f = ret_from_fork;

	}

	childregs->msr &= ~(MSR_FP|MSR_VEC|MSR_VSX);

	sp -= STACK_FRAME_OVERHEAD;



	/*

	 * The way this works is that at some point in the future
@@ -1806,7 +1808,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 
	 * do some house keeping and then return from the fork or clone

	 * system call, using the stack frame created above.

	 */

	((unsigned long *)sp)[0] = 0;

	sp -= sizeof(struct pt_regs);

	kregs = (struct pt_regs *) sp;

	sp -= STACK_FRAME_OVERHEAD;