@@ -1728,12 +1728,13 @@ 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 */
@@ -1753,6 +1754,7 @@ 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))
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: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/process.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)