x86: don't use privilege stack areas as a guard
This is causing problems, as if we create a thread in a system call we will *not* be using the kernel page tables if CONFIG_KPTI=n, resulting in a crash when the later call to copy_page_tables() tries to initialize the PDPT (which is in the same page as the privilege stack). Just don't fiddle with this page's permissions; we don't need it as a guard area anyway since we have a stack guard placed immediately before it, and this page is unused if user mode isn't active. Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
parent
6cfd8113a7
commit
9849c7d3e7
1 changed files with 3 additions and 23 deletions
|
@ -112,14 +112,6 @@ static FUNC_NORETURN void drop_to_user(k_thread_entry_t user_entry,
|
|||
FUNC_NORETURN void arch_user_mode_enter(k_thread_entry_t user_entry,
|
||||
void *p1, void *p2, void *p3)
|
||||
{
|
||||
struct z_x86_thread_stack_header *header =
|
||||
(struct z_x86_thread_stack_header *)_current->stack_obj;
|
||||
|
||||
/* Set up the kernel stack used during privilege elevation */
|
||||
z_x86_mmu_set_flags(&z_x86_kernel_ptables, &header->privilege_stack,
|
||||
MMU_PAGE_SIZE, MMU_ENTRY_WRITE, Z_X86_MMU_RW,
|
||||
true);
|
||||
|
||||
/* Initialize per-thread page tables, since that wasn't done when
|
||||
* the thread was initialized (K_USER was not set at creation time)
|
||||
*/
|
||||
|
@ -179,27 +171,15 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
|
|||
char *stack_buf;
|
||||
char *stack_high;
|
||||
struct _x86_initial_frame *initial_frame;
|
||||
#if defined(CONFIG_X86_USERSPACE) || defined(CONFIG_X86_STACK_PROTECTION)
|
||||
struct z_x86_thread_stack_header *header =
|
||||
(struct z_x86_thread_stack_header *)stack;
|
||||
#endif
|
||||
|
||||
Z_ASSERT_VALID_PRIO(priority, entry);
|
||||
stack_buf = Z_THREAD_STACK_BUFFER(stack);
|
||||
z_new_thread_init(thread, stack_buf, stack_size, priority, options);
|
||||
|
||||
#ifdef CONFIG_X86_USERSPACE
|
||||
/* Set MMU properties for the privilege mode elevation stack.
|
||||
* If we're not starting in user mode, this functions as a guard
|
||||
* area.
|
||||
*/
|
||||
z_x86_mmu_set_flags(&z_x86_kernel_ptables, &header->privilege_stack,
|
||||
MMU_PAGE_SIZE,
|
||||
((options & K_USER) == 0U) ? MMU_ENTRY_READ : MMU_ENTRY_WRITE,
|
||||
Z_X86_MMU_RW, true);
|
||||
#endif /* CONFIG_X86_USERSPACE */
|
||||
|
||||
#if CONFIG_X86_STACK_PROTECTION
|
||||
struct z_x86_thread_stack_header *header =
|
||||
(struct z_x86_thread_stack_header *)stack;
|
||||
|
||||
/* Set guard area to read-only to catch stack overflows */
|
||||
z_x86_mmu_set_flags(&z_x86_kernel_ptables, &header->guard_page,
|
||||
MMU_PAGE_SIZE, MMU_ENTRY_READ, Z_X86_MMU_RW,
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue