/*
- * Create a kernel thread
- *
- * int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
- * a2 a2 a3 a4
- */
-
-ENTRY(kernel_thread)
- entry a1, 16
-
- mov a5, a2 # preserve fn over syscall
- mov a7, a3 # preserve args over syscall
-
- movi a3, _CLONE_VM | _CLONE_UNTRACED
- movi a2, __NR_clone
- or a6, a4, a3 # arg0: flags
- mov a3, a1 # arg1: sp
- syscall
-
- beq a3, a1, 1f # branch if parent
- mov a6, a7 # args
- callx4 a5 # fn(args)
-
- movi a2, __NR_exit
- syscall # return value of fn(args) still in a6
-
-1: retw
-
-/*
- * Do a system call from kernel instead of calling sys_execve, so we end up
- * with proper pt_regs.
- *
- * int kernel_execve(const char *fname, char *const argv[], charg *const envp[])
- * a2 a2 a3 a4
- */
-
-ENTRY(kernel_execve)
- entry a1, 16
- mov a6, a2 # arg0 is in a6
- movi a2, __NR_execve
- syscall
-
- retw
-
-/*
* Task switch.
*
* struct task* _switch_to (struct task* prev, struct task* next)
j common_exception_return
+/*
+ * Kernel thread creation helper
+ * On entry, set up by copy_thread: a2 = thread_fn, a3 = thread_fn arg
+ * left from _switch_to: a6 = prev
+ */
+ENTRY(ret_from_kernel_thread)
+
+ call4 schedule_tail
+ mov a6, a3
+ callx4 a2
+ j common_exception_return
+
+ENDPROC(ret_from_kernel_thread)
#include <asm/regs.h>
extern void ret_from_fork(void);
+extern void ret_from_kernel_thread(void);
struct task_struct *current_set[NR_CPUS] = {&init_task, };
/*
* 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.
* 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
+ windowbase, windowstart and wmask.
+ (Note that such a new thread is required to always create
+ an initial call4 frame)
+ The exception is vfork, where the new thread continues to
+ run on the parent's stack until it calls execve. This could
+ be a call8 or call12, which requires a legal stack frame
+ of the previous caller for the overflow handlers to work.
+ (Note that it's always legal to overflow live registers).
+ In this case, ensure to spill at least the stack pointer
+ of that frame. */
+
if (clone_flags & CLONE_VM) {
- childregs->wmask = 1; /* can't share live windows */
+ /* check that caller window is live and same stack */
+ int len = childregs->wmask & ~0xf;
+ if (regs->areg[1] == usp && len != 0) {
+ int callinc = (regs->areg[0] >> 30) & 3;
+ int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
+ put_user(regs->areg[caller_ars+1],
+ (unsigned __user*)(usp - 12));
+ }
+ childregs->wmask = 1;
+ childregs->windowstart = 1;
+ childregs->windowbase = 0;
} else {
int len = childregs->wmask & ~0xf;
memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
// 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)
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);
}
-
-/*
- * xtensa_execve() executes a new program.
- */
-
-asmlinkage
-long xtensa_execve(const char __user *name,
- const char __user *const __user *argv,
- const char __user *const __user *envp,
- long a3, long a4, long a5,
- struct pt_regs *regs)
-{
- long error;
- struct filename *filename;
-
- filename = getname(name);
- error = PTR_ERR(filename);
- if (IS_ERR(filename))
- goto out;
- error = do_execve(filename->name, argv, envp, regs);
- putname(filename);
-out:
- return error;
-}
-
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / commitdiff