From f1b94abefa7d00a21e029de6d9732d7d7efea574 Mon Sep 17 00:00:00 2001
From: Marc Hartmayer <mhartmay@linux.ibm.com>
Date: Wed, 13 Nov 2024 12:32:57 +0000
Subject: [PATCH] rust/pv_core: Implement `Zeroize` trait for u* and i*
 primtives

Use a macro for the trait implementations.
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 rust/pv_core/src/confidential.rs | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/rust/pv_core/src/confidential.rs b/rust/pv_core/src/confidential.rs
index 61d7a067..5f51d798 100644
--- a/rust/pv_core/src/confidential.rs
+++ b/rust/pv_core/src/confidential.rs
@@ -12,6 +12,35 @@ pub trait Zeroize {
     fn zeroize(&mut self);
 }
 
+macro_rules! integer_impl {
+    ($typ:ty) => {
+        impl Zeroize for $typ {
+            /// Reliably overwrites the given number with zeros,
+            /// by performing a volatile write followed by a memory barrier
+            fn zeroize(&mut self) {
+                unsafe {
+                    std::ptr::write_volatile(self as *mut $typ, <$typ>::default());
+                }
+                std::sync::atomic::compiler_fence(std::sync::atomic::Ordering::SeqCst);
+            }
+        }
+    };
+}
+
+integer_impl!(u8);
+integer_impl!(u16);
+integer_impl!(u32);
+integer_impl!(u64);
+integer_impl!(u128);
+integer_impl!(usize);
+
+integer_impl!(i8);
+integer_impl!(i16);
+integer_impl!(i32);
+integer_impl!(i64);
+integer_impl!(i128);
+integer_impl!(isize);
+
 // Automatically impl Zeroize for u8 arrays
 impl<T: Default, const COUNT: usize> Zeroize for [T; COUNT] {
     /// Reliably overwrites the given buffer with zeros,