Merge #144

144: [RFC] rename UserHardFault to HardFault r=adamgreig a=japaric

so it matches the exception name (`#[exception] fn HardFault(..`)

Right now the symbol name of all exception handlers match the name of the
function used with the `#[exception]` attribute *except* for `HardFault`, whose
symbol name actually is `UserHardFault`.

This PR corrects that inconsistency by renaming the `UserHardFault` symbol to
`HardFault`, and the `HardFault` symbol to `HardFaultTrampoline`.

This change doesn't break compilation or changes functionality but it does soft
break GDB scripts that include the command `break UserHardFault` (e.g. the GDB
script in cortex-m-quickstart) in the sense that the breakpoint will no longer
work. However the rest of the GDB script will continue to work.

RFC questions: (a) do we want to do this rename? (b) if the answer is yes, do we
want to include this rename in the v0.5.x release, or should we consider it a
breaking change and postpone it until v0.6.0?

Co-authored-by: Jorge Aparicio <[email protected]>

Author: bors[bot]

cortex-m-rt/asm.s

@@ -1,10 +1,10 @@
   # LLD requires that the section flags are explicitly set here
-  .section .HardFault, "ax"
-  .global HardFault
+  .section .HardFaultTrampoline, "ax"
+  .global HardFaultTrampoline
   # .type and .thumb_func are both required; otherwise its Thumb bit does not
   # get set and an invalid vector table is generated
-  .type HardFault,%function
+  .type HardFaultTrampoline,%function
   .thumb_func
-HardFault:
+HardFaultTrampoline:
   mrs r0, MSP
-  b UserHardFault
+  b HardFault

cortex-m-rt/bin/thumbv6m-none-eabi.a

@@ -35,7 +35,7 @@ EXTERN(__EXCEPTIONS); /* depends on all the these PROVIDED symbols */
 EXTERN(DefaultHandler);
 
 PROVIDE(NonMaskableInt = DefaultHandler);
-EXTERN(HardFault);
+EXTERN(HardFaultTrampoline);
 PROVIDE(MemoryManagement = DefaultHandler);
 PROVIDE(BusFault = DefaultHandler);
 PROVIDE(UsageFault = DefaultHandler);
@@ -46,7 +46,7 @@ PROVIDE(PendSV = DefaultHandler);
 PROVIDE(SysTick = DefaultHandler);
 
 PROVIDE(DefaultHandler = DefaultHandler_);
-PROVIDE(UserHardFault = UserHardFault_);
+PROVIDE(HardFault = HardFault_);
 
 /* # Interrupt vectors */
 EXTERN(__INTERRUPTS); /* `static` variable similar to `__EXCEPTIONS` */
@@ -86,8 +86,8 @@ SECTIONS
   .text _stext :
   {
     *(.text .text.*);
-    *(.HardFault);
-    *(.UserHardFault);
+    *(.HardFaultTrampoline);
+    *(.HardFault.*);
   } > FLASH
 
   /* ### .rodata */

cortex-m-rt/bin/thumbv7em-none-eabi.a

@@ -397,8 +397,8 @@ pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream {
             let pat = &arg.pat;
 
             quote!(
-                #[export_name = "UserHardFault"]
-                #[link_section = ".UserHardFault"]
+                #[export_name = "HardFault"]
+                #[link_section = ".HardFault.user"]
                 #(#attrs)*
                 pub #unsafety extern "C" fn #hash(#arg) -> ! {
                     extern crate cortex_m_rt;

cortex-m-rt/bin/thumbv7em-none-eabihf.a

@@ -203,12 +203,12 @@
 //! - `DefaultHandler`. This is the default handler. If not overridden using `#[exception] fn
 //! DefaultHandler(..` this will be an infinite loop.
 //!
-//! - `HardFault`. This is the hard fault handler. This function is simply a trampoline that jumps
-//! into the user defined hard fault handler named `UserHardFault`. The trampoline is required to
-//! set up the pointer to the stacked exception frame.
+//! - `HardFaultTrampoline`. This is the real hard fault handler. This function is simply a
+//! trampoline that jumps into the user defined hard fault handler named `HardFault`. The
+//! trampoline is required to set up the pointer to the stacked exception frame.
 //!
-//! - `UserHardFault`. This is the user defined hard fault handler. If not overridden using
-//! `#[exception] fn HardFault(..` this will be an infinite loop.
+//! - `HardFault`. This is the user defined hard fault handler. If not overridden using
+//! `#[exception] fn HardFault(..` it will default to an infinite loop.
 //!
 //! - `__STACK_START`. This is the first entry in the `.vector_table` section. This symbol contains
 //! the initial value of the stack pointer; this is where the stack will be located -- the stack
@@ -534,9 +534,9 @@ pub unsafe extern "C" fn Reset() -> ! {
 
 #[allow(unused_variables)]
 #[doc(hidden)]
-#[link_section = ".UserHardFault"]
+#[link_section = ".HardFault.default"]
 #[no_mangle]
-pub unsafe extern "C" fn UserHardFault_(ef: &ExceptionFrame) -> ! {
+pub unsafe extern "C" fn HardFault_(ef: &ExceptionFrame) -> ! {
     loop {
         // add some side effect to prevent this from turning into a UDF instruction
         // see rust-lang/rust#28728 for details
@@ -590,7 +590,7 @@ pub enum Exception {
 extern "C" {
     fn NonMaskableInt();
 
-    fn HardFault();
+    fn HardFaultTrampoline();
 
     #[cfg(not(armv6m))]
     fn MemoryManagement();
@@ -629,7 +629,7 @@ pub static __EXCEPTIONS: [Vector; 14] = [
         handler: NonMaskableInt,
     },
     // Exception 3: Hard Fault Interrupt.
-    Vector { handler: HardFault },
+    Vector { handler: HardFaultTrampoline },
     // Exception 4: Memory Management Interrupt [not on Cortex-M0 variants].
     #[cfg(not(armv6m))]
     Vector {

cortex-m-rt/bin/thumbv7m-none-eabi.a

@@ -19,7 +19,7 @@ fn HardFault(_ef: &ExceptionFrame) -> ! {
 pub mod reachable {
     use cortex_m_rt::{exception, ExceptionFrame};
 
-    #[exception] //~ ERROR symbol `UserHardFault` is already defined
+    #[exception] //~ ERROR symbol `HardFault` is already defined
     fn HardFault(_ef: &ExceptionFrame) -> ! {
         loop {}
     }