If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> --- include/linux/init_task.h | 9 +++++++++ include/linux/sched.h | 36 ++++++++++++++++++++++++++++++++++-- include/linux/thread_info.h | 15 +++++++++++++++ init/Kconfig | 3 +++ init/init_task.c | 7 +++++-- kernel/sched/sched.h | 4 ++++ 6 files changed, 70 insertions(+), 4 deletions(-) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index f8834f820ec2..9c04d44eeb3c 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -15,6 +15,8 @@ #include <net/net_namespace.h> #include <linux/sched/rt.h> +#include <asm/thread_info.h> + #ifdef CONFIG_SMP # define INIT_PUSHABLE_TASKS(tsk) \ .pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO), @@ -183,12 +185,19 @@ extern struct task_group root_task_group; # define INIT_KASAN(tsk) #endif +#ifdef CONFIG_THREAD_INFO_IN_TASK +# define INIT_TASK_TI(tsk) .thread_info = INIT_THREAD_INFO(tsk), +#else +# define INIT_TASK_TI(tsk) +#endif + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) */ #define INIT_TASK(tsk) \ { \ + INIT_TASK_TI(tsk) \ .state = 0, \ .stack = init_stack, \ .usage = ATOMIC_INIT(2), \ diff --git a/include/linux/sched.h b/include/linux/sched.h index 569df670407a..4108b4880b86 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1456,6 +1456,13 @@ struct tlbflush_unmap_batch { }; struct task_struct { +#ifdef CONFIG_THREAD_INFO_IN_TASK + /* + * For reasons of header soup (see current_thread_info()), this + * must be the first element of task_struct. + */ + struct thread_info thread_info; +#endif volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */ void *stack; atomic_t usage; @@ -1465,6 +1472,9 @@ struct task_struct { #ifdef CONFIG_SMP struct llist_node wake_entry; int on_cpu; +#ifdef CONFIG_THREAD_INFO_IN_TASK + unsigned int cpu; /* current CPU */ +#endif unsigned int wakee_flips; unsigned long wakee_flip_decay_ts; struct task_struct *last_wakee; @@ -2557,7 +2567,9 @@ extern void set_curr_task(int cpu, struct task_struct *p); void yield(void); union thread_union { +#ifndef CONFIG_THREAD_INFO_IN_TASK struct thread_info thread_info; +#endif unsigned long stack[THREAD_SIZE/sizeof(long)]; }; @@ -3045,10 +3057,26 @@ static inline void threadgroup_change_end(struct task_struct *tsk) cgroup_threadgroup_change_end(tsk); } -#ifndef __HAVE_THREAD_FUNCTIONS +#ifdef CONFIG_THREAD_INFO_IN_TASK + +static inline struct thread_info *task_thread_info(struct task_struct *task) +{ + return &task->thread_info; +} +static inline void *task_stack_page(const struct task_struct *task) +{ + return task->stack; +} +#define setup_thread_stack(new,old) do { } while(0) +static inline unsigned long *end_of_stack(const struct task_struct *task) +{ + return task->stack; +} + +#elif !defined(__HAVE_THREAD_FUNCTIONS) #define task_thread_info(task) ((struct thread_info *)(task)->stack) -#define task_stack_page(task) ((task)->stack) +#define task_stack_page(task) ((void *)(task)->stack) static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org) { @@ -3348,7 +3376,11 @@ static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume) static inline unsigned int task_cpu(const struct task_struct *p) { +#ifdef CONFIG_THREAD_INFO_IN_TASK + return p->cpu; +#else return task_thread_info(p)->cpu; +#endif } static inline int task_node(const struct task_struct *p) diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 352b1542f5cc..b2b32d63bc8e 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -13,6 +13,21 @@ struct timespec; struct compat_timespec; +#ifdef CONFIG_THREAD_INFO_IN_TASK +struct thread_info { + u32 flags; /* low level flags */ +}; + +#define INIT_THREAD_INFO(tsk) \ +{ \ + .flags = 0, \ +} +#endif + +#ifdef CONFIG_THREAD_INFO_IN_TASK +#define current_thread_info() ((struct thread_info *)current) +#endif + /* * System call restart block. */ diff --git a/init/Kconfig b/init/Kconfig index f755a602d4a1..0c83af6d3753 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -26,6 +26,9 @@ config IRQ_WORK config BUILDTIME_EXTABLE_SORT bool +config THREAD_INFO_IN_TASK + bool + menu "General setup" config BROKEN diff --git a/init/init_task.c b/init/init_task.c index ba0a7f362d9e..11f83be1fa79 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -22,5 +22,8 @@ EXPORT_SYMBOL(init_task); * Initial thread structure. Alignment of this is handled by a special * linker map entry. */ -union thread_union init_thread_union __init_task_data = - { INIT_THREAD_INFO(init_task) }; +union thread_union init_thread_union __init_task_data = { +#ifndef CONFIG_THREAD_INFO_IN_TASK + INIT_THREAD_INFO(init_task) +#endif +}; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 7cbeb92a1cb9..a1cabcea4c54 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -999,7 +999,11 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) * per-task data have been completed by this moment. */ smp_wmb(); +#ifdef CONFIG_THREAD_INFO_IN_TASK + p->cpu = cpu; +#else task_thread_info(p)->cpu = cpu; +#endif p->wake_cpu = cpu; #endif } -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html