Merge #295

295: [backport] add CFI and size info to external assembly r=therealprof a=japaric

backport of #294

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

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Fixed
+
+- (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`)
+
 ## [v0.6.12] - 2020-01-26
 
 ### Fixed

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
@@ -17,6 +20,8 @@ HardFaultTrampoline:
 0:
   mrs r0, PSP
   b HardFault
+  .cfi_endproc
+  .size HardFaultTrampoline, . - HardFaultTrampoline
 
   # ARMv6-M leaves LR in an unknown state on Reset
   # this trampoline sets LR before it's pushed onto the stack by Reset
@@ -26,8 +31,11 @@ HardFaultTrampoline:
   # 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