From bc0677363d0ffaec0c56685291e97b080116976c Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sun, 27 Nov 2022 22:49:29 +1000 Subject: [PATCH] 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: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221127124942.1665522-5-npiggin@gmail.com --- arch/powerpc/kernel/process.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 5265da2..f93703e 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -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; -- 2.7.4