Merge #216

216: Add unwind information to external assembly r=jonas-schievink a=Tiwalun

Add unwind information to the external assembly files, as discussed in #215.

The `.debug_frame` section is now present:
```

cortex-m.o   (ex bin/thumbv6m-none-eabi.a):
section              size   addr
.text                 0x0    0x0
.data                 0x0    0x0
.bss                  0x0    0x0
.text.__bkpt          0x4    0x0
.text.__control_r     0x6    0x0
.text.__control_w     0x6    0x0
.text.__cpsid         0x4    0x0
.text.__cpsie         0x4    0x0
.text.__delay         0x8    0x0
.text.__dmb           0x6    0x0
.text.__dsb           0x6    0x0
.text.__isb           0x6    0x0
.text.__msp_r         0x6    0x0
.text.__msp_w         0x6    0x0
.text.__nop           0x2    0x0
.text.__primask       0x6    0x0
.text.__psp_r         0x6    0x0
.text.__psp_w         0x6    0x0
.text.__sev           0x4    0x0
.text.__udf           0x2    0x0
.text.__wfe           0x4    0x0
.text.__wfi           0x4    0x0
.debug_line         0x161    0x0
.debug_info          0x22    0x0
.debug_abbrev        0x12    0x0
.debug_aranges       0xb0    0x0
.debug_str           0x30    0x0
.debug_ranges        0xa8    0x0
.debug_frame        0x140    0x0
.ARM.attributes      0x1c    0x0
Total               0x4d9
```


Co-authored-by: Dominik Boehi <dominik.boehi@gmail.com>

Author: bors[bot]

asm-cm7-r0p1.s

@@ -1,7 +1,10 @@
+  .cfi_sections .debug_frame
+
   .section .text.__basepri_max_cm7_r0p1
   .global __basepri_max_cm7_r0p1
   .syntax unified
   .thumb_func
+  .cfi_startproc
 __basepri_max_cm7_r0p1:
   mrs r1, PRIMASK
   cpsid i
@@ -11,12 +14,14 @@ __basepri_max_cm7_r0p1:
   bxne lr
   cpsie i
   bx lr
+  .cfi_endproc
   .size __basepri_max_cm7_r0p1, . - __basepri_max_cm7_r0p1
 
   .section .text.__basepri_w_cm7_r0p1
   .global __basepri_w_cm7_r0p1
   .syntax unified
   .thumb_func
+  .cfi_startproc
 __basepri_w_cm7_r0p1:
   mrs r1, PRIMASK
   cpsid i
@@ -26,4 +31,5 @@ __basepri_w_cm7_r0p1:
   bxne lr
   cpsie i
   bx lr
+  .cfi_endproc
   .size __basepri_w_cm7_r0p1, . - __basepri_w_cm7_r0p1

asm-v7.s

@@ -1,31 +1,41 @@
+  .cfi_sections .debug_frame
+
   .section .text.__basepri_max
   .global __basepri_max
   .thumb_func
+  .cfi_startproc
 __basepri_max:
   msr BASEPRI_MAX, r0
   bx lr
+  .cfi_endproc
   .size __basepri_max, . - __basepri_max
 
   .section .text.__basepri_r
   .global __basepri_r
   .thumb_func
+  .cfi_startproc
 __basepri_r:
   mrs r0, BASEPRI
   bx lr
+  .cfi_endproc
   .size __basepri_r, . - __basepri_r
 
   .section .text.__basepri_w
   .global __basepri_w
   .thumb_func
+  .cfi_startproc
 __basepri_w:
   msr BASEPRI, r0
   bx lr
+  .cfi_endproc
   .size __basepri_w, . - __basepri_w
 
   .section .text.__faultmask
   .global __faultmask
   .thumb_func
+  .cfi_startproc
 __faultmask:
   mrs r0, FAULTMASK
   bx lr
+  .cfi_endproc
   .size __faultmask, . - __faultmask

asm-v8-main.s

@@ -1,32 +1,43 @@
+
+  .cfi_sections .debug_frame
+
   .section .text.__msplim_r
   .global __msplim_r
   .thumb_func
+  .cfi_startproc
 __msplim_r:
   mrs r0, MSPLIM
   bx lr
+  .cfi_endproc
   .size __msplim_r, . - __msplim_r
 
   .section .text.__msplim_w
   .global __msplim_w
   .thumb_func
+  .cfi_startproc
 __msplim_w:
   msr MSPLIM, r0
   bx lr
+  .cfi_endproc
   .size __msplim_w, . - __msplim_w
 
   .section .text.__psplim_r
   .global __psplim_r
   .thumb_func
+  .cfi_startproc
 __psplim_r:
   mrs r0, PSPLIM
   bx lr
+  .cfi_endproc
   .size __psplim_r, . - __psplim_r
 
   .section .text.__psplim_w
   .global __psplim_w
   .thumb_func
+  .cfi_startproc
 __psplim_w:
   msr PSPLIM, r0
   bx lr
+  .cfi_endproc
   .size __psplim_w, . - __psplim_w
 

asm-v8.s

@@ -1,32 +1,42 @@
+  .cfi_sections .debug_frame
+
   .section .text.__tt
   .global __tt
   .thumb_func
+  .cfi_startproc
 __tt:
   tt r0, r0
   bx lr
+  .cfi_endproc
   .size __tt, . - __tt
 
   .section .text.__ttt
   .global __ttt
   .thumb_func
+  .cfi_startproc
 __ttt:
   ttt r0, r0
   bx lr
+  .cfi_endproc
   .size __ttt, . - __ttt
 
   .section .text.__tta
   .global __tta
   .thumb_func
+  .cfi_startproc
 __tta:
   tta r0, r0
   bx lr
+  .cfi_endproc
   .size __tta, . - __tta
 
 
   .section .text.__ttat
   .global __ttat
   .thumb_func
+  .cfi_startproc
 __ttat:
   ttat r0, r0
   bx lr
+  .cfi_endproc
   .size __ttat, . - __ttat

asm.s

@@ -1,86 +1,108 @@
+  .cfi_sections .debug_frame
+
   .section .text.__bkpt
   .global __bkpt
   .thumb_func
+  .cfi_startproc
 __bkpt:
   bkpt
   bx lr
+  .cfi_endproc
   .size __bkpt, . - __bkpt
 
   .section .text.__control_r
   .global __control_r
   .thumb_func
+  .cfi_startproc
 __control_r:
   mrs r0, CONTROL
   bx lr
+  .cfi_endproc
   .size __control_r, . - __control_r
 
   .section .text.__control_w
   .global __control_w
   .thumb_func
+  .cfi_startproc
 __control_w:
   msr CONTROL, r0
   bx lr
+  .cfi_endproc
   .size __control_w, . - __control_w
 
 
   .section .text.__cpsid
   .global __cpsid
   .thumb_func
+  .cfi_startproc
 __cpsid:
   cpsid i
   bx lr
+  .cfi_endproc
   .size __cpsid, . - __cpsid
 
   .section .text.__cpsie
   .global __cpsie
   .thumb_func
+  .cfi_startproc
 __cpsie:
   cpsie i
   bx lr
+  .cfi_endproc
   .size __cpsie, . - __cpsie
 
   .section .text.__delay
   .global __delay
   .syntax unified
   .thumb_func
+  .cfi_startproc
 __delay:
 1:
   nop
   subs r0, #1
   bne 1b  // Branch to 1 instead of __delay does not generate R_ARM_THM_JUMP8 relocation, which breaks linking on the thumbv6m-none-eabi target
   bx lr
+  .cfi_endproc
   .size __delay, . - __delay
 
   .section .text.__dmb
   .global __dmb
   .thumb_func
+  .cfi_startproc
 __dmb:
   dmb 0xF
   bx lr
+  .cfi_endproc
   .size __dmb, . - __dmb
 
   .section .text.__dsb
   .global __dsb
   .thumb_func
+  .cfi_startproc
 __dsb:
   dsb 0xF
   bx lr
+  .cfi_endproc
   .size __dsb, . - __dsb
 
   .section .text.__isb
   .global __isb
   .thumb_func
+  .cfi_startproc
 __isb:
   isb 0xF
   bx lr
+  .cfi_endproc
   .size __isb, . - __isb
 
   .section .text.__msp_r
   .global __msp_r
   .thumb_func
+  .cfi_startproc
 __msp_r:
   mrs r0, MSP
   bx lr
+  .cfi_endproc
   .size __msp_r, . - __msp_r
 
   .section .text.__msp_w
@@ -94,24 +116,30 @@ __msp_w:
   .section .text.__nop
   .global __nop
   .thumb_func
+  .cfi_startproc
 __nop:
   bx lr
+  .cfi_endproc
   .size __nop, . - __nop
 
   .section .text.__primask
   .global __primask
   .thumb_func
+  .cfi_startproc
 __primask:
   mrs r0, PRIMASK
   bx lr
+  .cfi_endproc
   .size __primask, . - __primask
 
   .section .text.__psp_r
   .global __psp_r
   .thumb_func
+  .cfi_startproc
 __psp_r:
   mrs r0, PSP
   bx lr
+  .cfi_endproc
   .size __psp_r, . - __psp_r
 
   .section .text.__psp_w
@@ -125,32 +153,40 @@ __psp_w:
   .section .text.__sev
   .global __sev
   .thumb_func
+  .cfi_startproc
 __sev:
   sev
   bx lr
+  .cfi_endproc
   .size __sev, . - __sev
 
 
   .section .text.__udf
   .global __udf
   .thumb_func
+  .cfi_startproc
 __udf:
   udf
+  .cfi_endproc
   .size __udf, . - __udf
 
   .section .text.__wfe
   .global __wfe
   .thumb_func
+  .cfi_startproc
 __wfe:
   wfe
   bx lr
+  .cfi_endproc
   .size __wfe, . - __wfe
 
 
   .section .text.__wfi
   .global __wfi
   .thumb_func
+  .cfi_startproc
 __wfi:
   wfi
-  .size __wfi, . - __wfi
   bx lr
+  .cfi_endproc
+  .size __wfi, . - __wfi