diff --git a/pvmfw/src/exceptions.rs b/pvmfw/src/exceptions.rs
index 03fc220..42f4c3b 100644
--- a/pvmfw/src/exceptions.rs
+++ b/pvmfw/src/exceptions.rs
@@ -14,22 +14,21 @@
 
 //! Exception handlers.
 
-use crate::helpers::page_4kb_of;
-use core::arch::asm;
+use crate::{helpers::page_4kb_of, read_sysreg};
 use vmbase::console;
 use vmbase::{console::emergency_write_str, eprintln, power::reboot};
 
-const ESR_32BIT_EXT_DABT: u64 = 0x96000010;
+const ESR_32BIT_EXT_DABT: usize = 0x96000010;
 const UART_PAGE: usize = page_4kb_of(console::BASE_ADDRESS);
 
 #[no_mangle]
 extern "C" fn sync_exception_current(_elr: u64, _spsr: u64) {
-    let esr = read_esr();
-    let far = read_far();
+    let esr = read_sysreg!("esr_el1");
+    let far = read_sysreg!("far_el1");
     // Don't print to the UART if we're handling the exception it could raise.
-    if esr != ESR_32BIT_EXT_DABT || page_4kb_of(far as usize) != UART_PAGE {
+    if esr != ESR_32BIT_EXT_DABT || page_4kb_of(far) != UART_PAGE {
         emergency_write_str("sync_exception_current\n");
-        print_esr(esr);
+        eprintln!("esr={esr:#08x}");
     }
     reboot();
 }
@@ -48,17 +47,17 @@
 
 #[no_mangle]
 extern "C" fn serr_current(_elr: u64, _spsr: u64) {
-    let esr = read_esr();
+    let esr = read_sysreg!("esr_el1");
     emergency_write_str("serr_current\n");
-    print_esr(esr);
+    eprintln!("esr={esr:#08x}");
     reboot();
 }
 
 #[no_mangle]
 extern "C" fn sync_lower(_elr: u64, _spsr: u64) {
-    let esr = read_esr();
+    let esr = read_sysreg!("esr_el1");
     emergency_write_str("sync_lower\n");
-    print_esr(esr);
+    eprintln!("esr={esr:#08x}");
     reboot();
 }
 
@@ -76,31 +75,8 @@
 
 #[no_mangle]
 extern "C" fn serr_lower(_elr: u64, _spsr: u64) {
-    let esr = read_esr();
+    let esr = read_sysreg!("esr_el1");
     emergency_write_str("serr_lower\n");
-    print_esr(esr);
+    eprintln!("esr={esr:#08x}");
     reboot();
 }
-
-#[inline]
-fn read_esr() -> u64 {
-    let mut esr: u64;
-    unsafe {
-        asm!("mrs {esr}, esr_el1", esr = out(reg) esr);
-    }
-    esr
-}
-
-#[inline]
-fn print_esr(esr: u64) {
-    eprintln!("esr={:#08x}", esr);
-}
-
-#[inline]
-fn read_far() -> u64 {
-    let mut far: u64;
-    unsafe {
-        asm!("mrs {far}, far_el1", far = out(reg) far);
-    }
-    far
-}
diff --git a/pvmfw/src/helpers.rs b/pvmfw/src/helpers.rs
index e6e3406..9560d8d 100644
--- a/pvmfw/src/helpers.rs
+++ b/pvmfw/src/helpers.rs
@@ -22,6 +22,39 @@
 
 pub const GUEST_PAGE_SIZE: usize = SIZE_4KB;
 
+/// Read a value from a system register.
+#[macro_export]
+macro_rules! read_sysreg {
+    ($sysreg:literal) => {{
+        let mut r: usize;
+        // Safe because it reads a system register and does not affect Rust.
+        unsafe {
+            core::arch::asm!(
+                concat!("mrs {}, ", $sysreg),
+                out(reg) r,
+                options(nomem, nostack, preserves_flags),
+            )
+        }
+        r
+    }};
+}
+
+/// Write a value to a system register.
+#[macro_export]
+macro_rules! write_sysreg {
+    ($sysreg:literal, $val:expr) => {{
+        let value: usize = $val;
+        // Safe because it writes a system register and does not affect Rust.
+        unsafe {
+            core::arch::asm!(
+                concat!("msr ", $sysreg, ", {}"),
+                in(reg) value,
+                options(nomem, nostack, preserves_flags),
+            )
+        }
+    }};
+}
+
 /// Computes the largest multiple of the provided alignment smaller or equal to the address.
 ///
 /// Note: the result is undefined if alignment isn't a power of two.
@@ -78,9 +111,7 @@
 fn min_dcache_line_size() -> usize {
     const DMINLINE_SHIFT: usize = 16;
     const DMINLINE_MASK: usize = 0xf;
-    let ctr_el0: usize;
-
-    unsafe { asm!("mrs {x}, ctr_el0", x = out(reg) ctr_el0) }
+    let ctr_el0 = read_sysreg!("ctr_el0");
 
     // DminLine: log2 of the number of words in the smallest cache line of all the data caches.
     let dminline = (ctr_el0 >> DMINLINE_SHIFT) & DMINLINE_MASK;