Try #77:

Author: bors[bot]

asm.s

@@ -12,7 +12,7 @@ fn main() {
     let is_armv6m = is_armv6m(&target);
 
     if target.starts_with("thumbv") {
-        cc::Build::new().file("asm.s").compile("asm");
+        cc::Build::new().file("hardfault.s").compile("asm");
     }
 
     // Put the linker script somewhere the linker can find it

build.rs

@@ -0,0 +1,16 @@
+  .global HardFault
+  .thumb_func
+HardFault:
+  movs r0, #4
+  mov  r1, lr
+  tst  r0, r1      // Test bit[3] of EXC_RETURN to determine thread mode
+
+  beq HardFault.MSP
+
+HardFault.PSP:
+  mrs r0, PSP      // Use Process Stack Pointer (if in user mode)
+  bl UserHardFault // Jump to hard fault handler
+
+HardFault.MSP:
+  mrs r0, MSP      // Use Main Stack Pointer (if in privileged mode)
+  bl UserHardFault // Jump to hard fault handler