On Tue, Jun 09, 2020 at 02:25:09PM -0700, Guenter Roeck wrote:
> >
> > Still occurring on Linus' tree. This needs to be fixed. (And not by
> > removing
> > support for randstruct; that's not a "fix"...)
> >
>
> How about the hack below ?
>
> Guenter
>
> ---
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index c5d96e3e7fff..df1cbb04f9b3 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -629,6 +629,15 @@ struct wake_q_node {
> struct wake_q_node *next;
> };
>
> +/*
> + * Hack around assumption that wake_entry_type follows wake_entry even with
> + * CONFIG_GCC_PLUGIN_RANDSTRUCT=y.
> + */
> +struct _wake_entry {
> + struct llist_node wake_entry;
> + unsigned int wake_entry_type;
> +};
> +
> struct task_struct {
> #ifdef CONFIG_THREAD_INFO_IN_TASK
> /*
> @@ -653,8 +662,9 @@ struct task_struct {
> unsigned int ptrace;
>
> #ifdef CONFIG_SMP
> - struct llist_node wake_entry;
> - unsigned int wake_entry_type;
> + struct _wake_entry _we;
> +#define wake_entry _we.wake_entry
> +#define wake_entry_type _we.wake_entry_type
> int on_cpu;
> #ifdef CONFIG_THREAD_INFO_IN_TASK
> /* Current CPU: */
Does the struct actually have to be named? How about:
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c5d96e3e7fff42..14ca25cda19150 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -653,8 +653,14 @@ struct task_struct {
unsigned int ptrace;
#ifdef CONFIG_SMP
- struct llist_node wake_entry;
- unsigned int wake_entry_type;
+ /*
+ * wake_entry_type must follow wake_entry, even when
+ * CONFIG_GCC_PLUGIN_RANDSTRUCT=y.
+ */
+ struct {
+ struct llist_node wake_entry;
+ unsigned int wake_entry_type;
+ };
int on_cpu;
#ifdef CONFIG_THREAD_INFO_IN_TASK
/* Current CPU: */
However, it would be preferable to not rely on different structs sharing the
same field order, but rather write proper C code that uses the same struct
everywhere to encapsulate these 2 fields...
- Eric
