Merge #294

294: add CFI and size info r=jonas-schievink a=japaric

like it was done in rust-embedded/cortex-m#216 and rust-embedded/cortex-m#212

Co-authored-by: Jorge Aparicio <jorge.aparicio@ferrous-systems.com>

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Various fixes to the linker script ([#265], [#286]).
 - Use the correct ABI for the `main` symbol ([#278]).
 - Add barriers after FPU enabling ([#279]).
+- (ARMv6-M) Set LR value to a known value on reset (as the ARM spec requires)
+- Added CFI and size info to external assembly subroutines (`HardFaultTrampoline` and `FpuTrampoline`)
 
 [#265]: https://github.com/rust-embedded/cortex-m-rt/pull/265
 [#278]: https://github.com/rust-embedded/cortex-m-rt/pull/278

asm.s

@@ -1,10 +1,13 @@
+  .cfi_sections .debug_frame
+
   # LLD requires that the section flags are explicitly set here
   .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 HardFaultTrampoline,%function
   .thumb_func
+  .cfi_startproc
 HardFaultTrampoline:
   # depending on the stack mode in EXC_RETURN, fetch stack pointer from
   # PSP or MSP
@@ -17,13 +20,16 @@ HardFaultTrampoline:
 0:
   mrs r0, PSP
   b HardFault
+  .cfi_endproc
+  .size HardFaultTrampoline, . - HardFaultTrampoline
 
   .section .text.FpuTrampoline, "ax"
   .global FpuTrampoline
   # .type and .thumb_func are both required; otherwise its Thumb bit does not
   # get set and an invalid vector table is generated
   .type FpuTrampoline,%function
   .thumb_func
+  .cfi_startproc
   # This enables the FPU and jumps to the main function.
 FpuTrampoline:
   # Address of SCB.CPACR.
@@ -40,6 +46,8 @@ FpuTrampoline:
   # Hand execution over to `main`.
   bl main
   # Note: `main` must not return. `bl` is used only because it has a wider range than `b`.
+  .cfi_endproc
+  .size FpuTrampoline, . - FpuTrampoline
 
   # ARMv6-M leaves LR in an unknown state on Reset
   # this trampoline sets LR before it's pushed onto the stack by Reset
@@ -49,8 +57,11 @@ FpuTrampoline:
   # get set and an invalid vector table is generated
   .type PreResetTrampoline,%function
   .thumb_func
+  .cfi_startproc
 PreResetTrampoline:
   # set LR to the initial value used by the ARMv7-M (0xFFFF_FFFF)
   ldr r0,=0xffffffff
   mov lr,r0
   b Reset
+  .cfi_endproc
+  .size PreResetTrampoline, . - PreResetTrampoline