On 10/31, Christian Brauner wrote:
--- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -51,6 +51,10 @@
sent when the child exits.- @stack: Specify the location of the stack for the
child process.
Note, @stack is expected to point to the
lowest address. The stack direction will be
determined by the kernel and set up
appropriately based on @stack_size.
I can't review this patch, I have no idea what does stack_size mean if !arch/x86.
x86 doesn't use stack_size unless a kthread does kernel_thread(), so this change is probably fine...
Hmm. Off-topic question, why did 7f192e3cd3 ("fork: add clone3") add "& ~CSIGNAL" in kernel_thread() ? This looks pointless and confusing to me...
+static inline bool clone3_stack_valid(struct kernel_clone_args *kargs) +{
- if (kargs->stack == 0) {
if (kargs->stack_size > 0)return false;- } else {
if (kargs->stack_size == 0)return false;
So to implement clone3_wrapper(void *bottom_of_stack) you need to do
clone3_wrapper(void *bottom_of_stack) { struct clone_args args = { ... // make clone3_stack_valid() happy .stack = bottom_of_stack - 1, .stack_size = 1, }; }
looks a bit strange. OK, I agree, this example is very artificial. But why do you think clone3() should nack stack_size == 0 ?
if (!access_ok((void __user *)kargs->stack, kargs->stack_size))return false;
Why?
Oleg.