When allocating user memory space for a compat system call, don't consider
whether the originating code is IA32 or X32, just allocate from a safe
region for both, beyond the redzone. This should be safe for IA32, and has
the benefit of avoiding TIF_IA32, which is about to be removed.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201004032536.1229030-3-krisman@collabora.com
static inline void __user *arch_compat_alloc_user_space(long len)
{
- compat_uptr_t sp;
-
- if (test_thread_flag(TIF_IA32)) {
- sp = task_pt_regs(current)->sp;
- } else {
- /* -128 for the x32 ABI redzone */
- sp = task_pt_regs(current)->sp - 128;
- }
+ compat_uptr_t sp = task_pt_regs(current)->sp;
+
+ /*
+ * -128 for the x32 ABI redzone. For IA32, it is not strictly
+ * necessary, but not harmful.
+ */
+ sp -= 128;
return (void __user *)round_down(sp - len, 16);
}