Messages in this thread Patch in this message | | | From | Wang Dongsheng <> | Subject | [PATCH 1/1] sched/headers: fix thread_info.<first> is overwritten by STACK_END_MAGIC | Date | Fri, 23 Nov 2018 15:54:48 +0800 |
| |
When select ARCH_TASK_STRUCT_ON_STACK the first of thread_info variable is overwritten by STACK_END_MAGIC. In fact, the ARCH_TASK_STRUCT_ON_STACK is not a real task on stack, it's only init_task on init_stack.
Commit 0500871f21b2 ("Construct init thread stack in the linker script rather than by union") added this macro and put task_strcut into thread_union. This brings us the following possibilities: TASK_ON_STACK THREAD_INFO_IN_TASK STACK ----- <-- thread_info & stack N N | | --- <-- task | | | | ----- ---
----- <-- stack N Y | | --- <-- task(Including thread_info) | | | | ----- ---
----- <-- stack & task & thread_info Y N | | | | -----
----- <-- stack & task(Including thread_info) Y Y | | | | ----- The kernel has handled the first two cases correctly.
For the third case: TASK_ON_STACK: Y. THREAD_INFO_IN_TASK: N. this case should never happen, because the task and thread_info will overlap. So when TASK_ON_STACK is selected, THREAD_INFO_IN_TASK must be selected too.
For the fourth case: When task on stack, the end of stack should add a sizeof(task_struct) offset.
This patch handled with the third and fourth case.
Fixes: 0500871f21b2 ("Construct init thread stack in the linker ...")
Signed-off-by: Wang Dongsheng <dongsheng.wang@hxt-semitech.com> Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com> --- arch/Kconfig | 1 + include/linux/sched/task_stack.h | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/Kconfig b/arch/Kconfig index e1e540ffa979..0a2c73e73195 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -251,6 +251,7 @@ config ARCH_HAS_SET_MEMORY # Select if arch init_task must go in the __init_task_data section config ARCH_TASK_STRUCT_ON_STACK bool + depends on THREAD_INFO_IN_TASK || IA64 # Select if arch has its private alloc_task_struct() function config ARCH_TASK_STRUCT_ALLOCATOR diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h index 6a841929073f..624c48defb9e 100644 --- a/include/linux/sched/task_stack.h +++ b/include/linux/sched/task_stack.h @@ -7,6 +7,7 @@ */ #include <linux/sched.h> +#include <linux/sched/task.h> #include <linux/magic.h> #ifdef CONFIG_THREAD_INFO_IN_TASK @@ -25,7 +26,9 @@ static inline void *task_stack_page(const struct task_struct *task) static inline unsigned long *end_of_stack(const struct task_struct *task) { - return task->stack; + if (!IS_ENABLED(CONFIG_ARCH_TASK_STRUCT_ON_STACK) || task != &init_task) + return task->stack; + return (unsigned long *)(task + 1); } #elif !defined(__HAVE_THREAD_FUNCTIONS) -- 2.19.1
| |