Commit 6895dfc0 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc: copy_thread fill in interrupt frame marker and back chain 



Backtraces will not recognise the fork system call interrupt without
the regs marker. And regular interrupt entry from userspace creates
the back chain to the user stack, so do this for the initial fork
frame too, to be consistent.

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/20221127124942.1665522-13-npiggin@gmail.com
parent 6f291a03

arch/powerpc/kernel/process.c

+3 −1
Original line number Diff line number Diff line
@@ -1757,12 +1757,13 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 


	/* Create initial stack frame. */

	sp -= STACK_USER_INT_FRAME_SIZE;

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

	*(unsigned long *)(sp + STACK_INT_FRAME_MARKER) = STACK_FRAME_REGS_MARKER;



	/* Copy registers */

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

	if (unlikely(args->fn)) {

		/* kernel thread */

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

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

		childregs->gpr[1] = sp + STACK_USER_INT_FRAME_SIZE;

		/* function */
@@ -1782,6 +1783,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 
		*childregs = *regs;

		if (usp)

			childregs->gpr[1] = usp;

		((unsigned long *)sp)[0] = childregs->gpr[1];

		p->thread.regs = childregs;

		/* 64s sets this in ret_from_fork */

		if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64))