From 6895dfc0474170c492191c126fcfc420f7771a09 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sun, 27 Nov 2022 22:49:37 +1000 Subject: [PATCH] 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: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221127124942.1665522-13-npiggin@gmail.com --- arch/powerpc/kernel/process.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 0cb5296c6c41e8..6b1d80bd370ea6 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -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))