From 3306a72669a2af23b324540b08e68e82ac5b7dab Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Thu, 25 Oct 2012 11:10:50 +0400 Subject: xtensa: switch to generic kernel_thread() Signed-off-by: Max Filippov Signed-off-by: Chris Zankel --- arch/xtensa/kernel/process.c | 77 ++++++++++++++++++++++++++------------------ 1 file changed, 46 insertions(+), 31 deletions(-) (limited to 'arch/xtensa/kernel/process.c') diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index 341c151af919..be52fe437c1b 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -45,6 +45,7 @@ #include extern void ret_from_fork(void); +extern void ret_from_kernel_thread(void); struct task_struct *current_set[NR_CPUS] = {&init_task, }; @@ -158,18 +159,30 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) /* * Copy thread. * + * There are two modes in which this function is called: + * 1) Userspace thread creation, + * regs != NULL, usp_thread_fn is userspace stack pointer. + * It is expected to copy parent regs (in case CLONE_VM is not set + * in the clone_flags) and set up passed usp in the childregs. + * 2) Kernel thread creation, + * regs == NULL, usp_thread_fn is the function to run in the new thread + * and thread_fn_arg is its parameter. + * childregs are not used for the kernel threads. + * * The stack layout for the new thread looks like this: * - * +------------------------+ <- sp in childregs (= tos) + * +------------------------+ * | childregs | * +------------------------+ <- thread.sp = sp in dummy-frame * | dummy-frame | (saved in dummy-frame spill-area) * +------------------------+ * - * We create a dummy frame to return to ret_from_fork: - * a0 points to ret_from_fork (simulating a call4) + * We create a dummy frame to return to either ret_from_fork or + * ret_from_kernel_thread: + * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4) * sp points to itself (thread.sp) - * a2, a3 are unused. + * a2, a3 are unused for userspace threads, + * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads. * * Note: This is a pristine frame, so we don't need any spill region on top of * childregs. @@ -185,41 +198,37 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) * involved. Much simpler to just not copy those live frames across. */ -int copy_thread(unsigned long clone_flags, unsigned long usp, - unsigned long unused, - struct task_struct * p, struct pt_regs * regs) +int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn, + unsigned long thread_fn_arg, + struct task_struct *p, struct pt_regs *unused) { - struct pt_regs *childregs; - unsigned long tos; - int user_mode = user_mode(regs); + struct pt_regs *childregs = task_pt_regs(p); #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS) struct thread_info *ti; #endif - /* Set up new TSS. */ - tos = (unsigned long)task_stack_page(p) + THREAD_SIZE; - if (user_mode) - childregs = (struct pt_regs*)(tos - PT_USER_SIZE); - else - childregs = (struct pt_regs*)tos - 1; - - /* This does not copy all the regs. In a bout of brilliance or madness, - ARs beyond a0-a15 exist past the end of the struct. */ - *childregs = *regs; - /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */ *((int*)childregs - 3) = (unsigned long)childregs; *((int*)childregs - 4) = 0; - childregs->areg[2] = 0; - p->set_child_tid = p->clear_child_tid = NULL; - p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1); p->thread.sp = (unsigned long)childregs; - if (user_mode(regs)) { + if (!(p->flags & PF_KTHREAD)) { + struct pt_regs *regs = current_pt_regs(); + unsigned long usp = usp_thread_fn ? + usp_thread_fn : regs->areg[1]; + + p->thread.ra = MAKE_RA_FOR_CALL( + (unsigned long)ret_from_fork, 0x1); + /* This does not copy all the regs. + * In a bout of brilliance or madness, + * ARs beyond a0-a15 exist past the end of the struct. + */ + *childregs = *regs; childregs->areg[1] = usp; + childregs->areg[2] = 0; /* When sharing memory with the parent thread, the child usually starts on a pristine stack, so we have to reset @@ -254,11 +263,19 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, // FIXME: we need to set THREADPTR in thread_info... if (clone_flags & CLONE_SETTLS) childregs->areg[2] = childregs->areg[6]; - } else { - /* In kernel space, we start a new thread with a new stack. */ - childregs->wmask = 1; - childregs->areg[1] = tos; + p->thread.ra = MAKE_RA_FOR_CALL( + (unsigned long)ret_from_kernel_thread, 1); + + /* pass parameters to ret_from_kernel_thread: + * a2 = thread_fn, a3 = thread_fn arg + */ + *((int *)childregs - 1) = thread_fn_arg; + *((int *)childregs - 2) = usp_thread_fn; + + /* Childregs are only used when we're going to userspace + * in which case start_thread will set them up. + */ } #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS) @@ -354,8 +371,6 @@ long xtensa_clone(unsigned long clone_flags, unsigned long newsp, void __user *child_tid, long a5, struct pt_regs *regs) { - if (!newsp) - newsp = regs->areg[1]; return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid); } -- cgit v1.2.3-59-g8ed1b