When CONFIG_ARCH_HAS_VARIABLE_STACK_SIZE is enabled, the kernel stack may not be fully populated with the THREAD_SIZE virtual area.
Teach task_stack_size() to return the size of the vm area and not a fixed size. This propagates to end_of_stack() which makes functions like stack_not_used() and set_task_stack_end_magic() to use the lowest valid stack address instead of THREAD_SIZE which would cause data aborts. Signed-off-by: Mostafa Saleh <[email protected]> --- arch/Kconfig | 10 ++++++++++ include/linux/sched/task_stack.h | 5 +++++ 2 files changed, 15 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index 45c657772362..d6fa2ccb0599 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -431,6 +431,16 @@ config HAVE_ASM_MODVERSIONS <asm/asm-prototypes.h> to support the module versioning for symbols exported from assembly code. +config ARCH_HAS_VARIABLE_STACK_SIZE + bool + depends on VMAP_STACK + depends on !STACK_GROWSUP + depends on THREAD_INFO_IN_TASK + help + An arch should select this if it supports dynamically configuring the + kernel stack size. + For example the kernel stack size can be from the command line. + config HAVE_REGS_AND_STACK_ACCESS_API bool help diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h index 4a808f9c4631..07d73adaecd1 100644 --- a/include/linux/sched/task_stack.h +++ b/include/linux/sched/task_stack.h @@ -10,6 +10,7 @@ #include <linux/magic.h> #include <linux/refcount.h> #include <linux/kasan.h> +#include <linux/vmalloc.h> #ifdef CONFIG_THREAD_INFO_IN_TASK @@ -96,6 +97,10 @@ static inline unsigned long *end_of_stack(const struct task_struct *p) */ static __always_inline unsigned long task_stack_size(const struct task_struct *task) { +#ifdef CONFIG_ARCH_HAS_VARIABLE_STACK_SIZE + if (task->stack_vm_area) + return task->stack_vm_area->nr_pages * PAGE_SIZE; +#endif return THREAD_SIZE; } -- 2.56.0.rc1.315.gc6ed9934b7-goog
