arm64: Add support for STACKLEAK gcc plugin
This adds support for the STACKLEAK gcc plugin to arm64 by implementing
stackleak_check_alloca(), based heavily on the x86 version, and adding the
two helpers used by the stackleak common code: current_top_of_stack() and
on_thread_stack(). The stack erasure calls are made at syscall returns.
Additionally, this disables the plugin in hypervisor and EFI stub code,
which are out of scope for the protection.
Acked-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index d1440f8..09dbea2 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -902,6 +902,9 @@
cbnz x2, work_pending
finish_ret_to_user:
enable_step_tsk x1, x2
+#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
+ bl stackleak_erase
+#endif
kernel_exit 0
ENDPROC(ret_to_user)
