In preparation for performing actions during ptrace syscall exit, save the syscall number during ptrace syscall entry. Some architectures do no have the syscall number available during ptrace syscall exit. Suggested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Link: https://lore.kernel.org/linux-kselftest/20200911181012.171027-1-cascardo@canonical.com/ Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/lkml/20200921074354.6shkt2e5yhzhj3sn@wittgenstein/ Signed-off-by: Kees Cook <keescook@chromium.org>