diff options
| -rw-r--r-- | cortex-m-rt/Cargo.toml | 1 | ||||
| -rw-r--r-- | cortex-m-rt/link.x.in | 5 | ||||
| -rw-r--r-- | cortex-m-rt/src/lib.rs | 31 |
3 files changed, 23 insertions, 14 deletions
diff --git a/cortex-m-rt/Cargo.toml b/cortex-m-rt/Cargo.toml index d22c5df..9cd9d19 100644 --- a/cortex-m-rt/Cargo.toml +++ b/cortex-m-rt/Cargo.toml @@ -21,4 +21,3 @@ panic-abort = "0.2.0" [features] device = [] -pre_init = [] diff --git a/cortex-m-rt/link.x.in b/cortex-m-rt/link.x.in index dfcf262..02cdb32 100644 --- a/cortex-m-rt/link.x.in +++ b/cortex-m-rt/link.x.in @@ -51,6 +51,11 @@ PROVIDE(UserHardFault = DefaultUserHardFault); /* # Interrupt vectors */ EXTERN(__INTERRUPTS); /* `static` variable similar to `__EXCEPTIONS` */ +/* # Pre-initialization function */ +/* If the user overrides this using the `pre_init!` macro or by creating a `__pre_init` function, + then the function this points to will be called before the RAM is initialized. */ +PROVIDE(__pre_init = 0); + /* # Sections */ SECTIONS { diff --git a/cortex-m-rt/src/lib.rs b/cortex-m-rt/src/lib.rs index 7b023ed..d73dc4f 100644 --- a/cortex-m-rt/src/lib.rs +++ b/cortex-m-rt/src/lib.rs @@ -169,13 +169,6 @@ //! conjunction with crates generated using `svd2rust`. Those *device crates* will populate the //! missing part of the vector table when their `"rt"` feature is enabled. //! -//! ## `pre_init` -//! -//! If this feature is enabled then a user-defined function will be run at the start of the reset -//! handler, before RAM is initialized. If this feature is enabled then the macro `pre_init!` needs -//! to be called to set the function to be run. This feature is intended to perform actions that -//! cannot wait the time it takes for RAM to be initialized, such as disabling a watchdog. -//! //! # Inspection //! //! This section covers how to inspect a binary that builds on top of `cortex-m-rt`. @@ -244,6 +237,10 @@ //! have a size of 32 vectors (on ARMv6-M) or 240 vectors (on ARMv7-M). This array is located after //! `__EXCEPTIONS` in the `.vector_table` section. //! +//! - `__pre_init`. This is a function to be run before RAM is initialized. It defaults pointing at +//! `0` and if not changed to point to another address, usually by calling the `pre_init!` macro, +//! the `_pre_init` function is skipped. +//! //! If you override any exception handler you'll find it as an unmangled symbol, e.g. `SysTick` or //! `SVCall`, in the output of `objdump`, //! @@ -385,6 +382,14 @@ //! println!("cargo:rustc-link-search={}", out.display()); //! } //! ``` +//! +//! ## `pre_init!` +//! +//! A user-defined function can be run at the start of the reset handler, before RAM is +//! initialized. The macro `pre_init!` can be called to set the function to be run. The function is +//! intended to perform actions that cannot wait the time it takes for RAM to be initialized, such +//! as disabling a watchdog. As the function is called before RAM is initialized, any access of +//! static variables will result in undefined behavior. // # Developer notes // @@ -482,12 +487,13 @@ pub unsafe extern "C" fn Reset() -> ! { static mut __edata: u32; static __sidata: u32; - #[cfg(feature = "pre_init")] - fn _pre_init(); + fn __pre_init(); } - #[cfg(feature = "pre_init")] - _pre_init(); + let pre_init: unsafe extern "C" fn() = __pre_init; + if pre_init as usize != 0 { + pre_init(); + } // Initialize RAM r0::zero_bss(&mut __sbss, &mut __ebss); @@ -904,14 +910,13 @@ macro_rules! exception { /// } /// } /// ``` -#[cfg(feature = "pre_init")] #[macro_export] macro_rules! pre_init { ($handler:path) => { #[allow(unsafe_code)] #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible #[no_mangle] - pub unsafe extern "C" fn _pre_init() { + pub unsafe extern "C" fn __pre_init() { // validate user handler let f: unsafe fn() = $handler; f(); |