From fb77914a692d550a5bb0c7f71eac40e6da9c0e6d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 6 Mar 2023 00:55:33 +0000 Subject: [PATCH] s390: trim ancient junk from copy_thread() Setting and ->psw.addr in childregs of kernel thread is a rudiment of the old kernel_thread()/kernel_execve() implementation. Mainline hadn't been using them since 2012. And clarify the assignments to frame->sf.gprs - the array stores grp6..gpr15 values to be set by __switch_to(), so frame->sf.gprs[5] actually affects grp11, etc. Better spell that as frame->sf.gprs[11 - 6]... Signed-off-by: Al Viro Link: https://lore.kernel.org/r/ZAU6BYFisE8evmYf@ZenIV Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/kernel/process.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 67df64e..87ca3a7 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -136,12 +136,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.last_break = 1; frame->sf.back_chain = 0; - frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame); - frame->sf.gprs[6] = (unsigned long)p; + frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; + frame->sf.gprs[12 - 6] = (unsigned long)p; /* new return point is ret_from_fork */ - frame->sf.gprs[8] = (unsigned long)ret_from_fork; + frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork; /* fake return stack for resume(), don't go back to schedule */ - frame->sf.gprs[9] = (unsigned long)frame; + frame->sf.gprs[15 - 6] = (unsigned long)frame; /* Store access registers to kernel stack of new process. */ if (unlikely(args->fn)) { @@ -149,8 +149,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) memset(&frame->childregs, 0, sizeof(struct pt_regs)); frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; - frame->childregs.psw.addr = - (unsigned long)__ret_from_fork; frame->childregs.gprs[9] = (unsigned long)args->fn; frame->childregs.gprs[10] = (unsigned long)args->fn_arg; frame->childregs.orig_gpr2 = -1; -- 2.7.4