diff options
Diffstat (limited to 'src/asm.rs')
| -rw-r--r-- | src/asm.rs | 24 |
1 files changed, 14 insertions, 10 deletions
@@ -165,7 +165,7 @@ pub unsafe fn bx_ns(addr: u32) { call_asm!(__bxns(addr: u32)); } -/// Semihosing syscall. +/// Semihosting syscall. /// /// This method is used by cortex-m-semihosting to provide semihosting syscalls. #[inline] @@ -175,15 +175,20 @@ pub unsafe fn sh_syscall(nr: u32, arg: u32) -> u32 { /// Bootstrap. /// -/// Sets the active stack to the main stack, updates the main stack pointer to `msp`, -/// then jumps execution to the address in `rv`. -/// Writes `msp` to the MSP special register, then jumps to the address in `rv`. +/// Clears CONTROL.SPSEL (setting the main stack to be the active stack), +/// updates the main stack pointer to the address in `msp`, then jumps +/// to the address in `rv`. +/// +/// # Safety +/// +/// `msp` and `rv` must point to valid stack memory and executable code, +/// respectively. #[inline] pub unsafe fn bootstrap(msp: *const u32, rv: *const u32) -> ! { + // Ensure thumb mode is set. + let rv = (rv as u32) | 1; let msp = msp as u32; - let rv = rv as u32; - call_asm!(__bootstrap(msp: u32, rv: u32)); - core::hint::unreachable_unchecked(); + call_asm!(__bootstrap(msp: u32, rv: u32) -> !); } /// Bootload. @@ -191,14 +196,13 @@ pub unsafe fn bootstrap(msp: *const u32, rv: *const u32) -> ! { /// Reads the initial stack pointer value and reset vector from /// the provided vector table address, sets the active stack to /// the main stack, sets the main stack pointer to the new initial -/// stack pointer view, then jumps to the reset vector. +/// stack pointer, then jumps to the reset vector. /// /// # Safety /// /// The provided `vector_table` must point to a valid vector /// table, with a valid stack pointer as the first word and -/// a valid reset vector (in thumb mode, with the least significant -/// bit cleared) as the second word. +/// a valid reset vector as the second word. #[inline] pub unsafe fn bootload(vector_table: *const u32) -> ! { let msp = core::ptr::read_volatile(vector_table); |