arm64: Check user stack pointer on syscall entry

Allow the user stack pointer value to be checked on system call entry
and deliver a SIGSEGV if the check does not pass.

Cc: Jann Horn <>
Cc: Andrew Morton <>
Cc: Matthew Wilcox <>
Cc: Michal Hocko <>
Cc: Peter Zijlstra <>
Reviewed-by: Kees Cook <>
Signed-off-by: Will Deacon <>
2 files changed