diff --git a/cortex-m-rt/ci/script.sh b/cortex-m-rt/ci/script.sh index 60e88d7d..713121c7 100755 --- a/cortex-m-rt/ci/script.sh +++ b/cortex-m-rt/ci/script.sh @@ -21,6 +21,7 @@ main() { divergent-default-handler divergent-exception entry-static + hard-fault-trampoline main minimal override-exception diff --git a/cortex-m-rt/examples/hard-fault-trampoline.rs b/cortex-m-rt/examples/hard-fault-trampoline.rs new file mode 100644 index 00000000..995e7ce2 --- /dev/null +++ b/cortex-m-rt/examples/hard-fault-trampoline.rs @@ -0,0 +1,31 @@ +//! This is not an example; this is a linker test that ensures +//! that the jump from HardFault to _HardFault doesn't exceed +//! the 2kB limit of the branch instruction. + +#![deny(warnings)] +#![no_main] +#![no_std] + +extern crate cortex_m_rt; +extern crate panic_halt; + +use core::arch::asm; +use cortex_m_rt::{entry, exception, ExceptionFrame}; + +// This defines both `HardFault` and `_HardFault`. Both should have +// link_section attributes placing them at the end of the .text section, +// close to each other. If one of them is missing that attribute, they +// will end up separated by `foo`, which will make the linker fail. +#[exception(trampoline = true)] +unsafe fn HardFault(_ef: &ExceptionFrame) -> ! { + loop {} +} + +#[entry] +fn foo() -> ! { + unsafe { + // 2kB of NOP instructions to make the function artificially larger + asm!(".fill 1024,2,0xbf00",); + } + loop {} +} diff --git a/cortex-m-rt/macros/src/lib.rs b/cortex-m-rt/macros/src/lib.rs index f8f0ca0f..d10a711a 100644 --- a/cortex-m-rt/macros/src/lib.rs +++ b/cortex-m-rt/macros/src/lib.rs @@ -368,6 +368,10 @@ pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream { #(#attrs)* #[doc(hidden)] #[export_name = "_HardFault"] + // Only emit link_section when building for embedded targets, + // because some hosted platforms (used to check the build) + // cannot handle the long link section names. + #[cfg_attr(target_os = "none", link_section = ".HardFault.user")] unsafe extern "C" fn #tramp_ident(frame: &::cortex_m_rt::ExceptionFrame) { #ident(frame) } @@ -379,7 +383,7 @@ pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream { // Depending on the stack mode in EXC_RETURN, fetches stack from either MSP or PSP. core::arch::global_asm!( ".cfi_sections .debug_frame - .section .HardFault.user, \"ax\" + .section .HardFaultTrampoline, \"ax\" .global HardFault .type HardFault,%function .thumb_func