[nrf fromtree] arch: arm: cortex_m: use local label in ASM code

Regular label are exported in the object file and cause gdb to consider
them as function start. Local labels on the other hand are not exported.
For example, using `disassemble z_arm_pendsv` after this change will
disassemble the whole function rather than stop at the first branch.

Signed-off-by: Wilfried Chauveau <[email protected]>
(cherry picked from commit 5261680)

Author: ithinuel

arch/arm/core/cortex_m/pm_s2ram.S

@@ -221,10 +221,10 @@ SECTION_FUNC(TEXT, arch_pm_s2ram_resume)
 	bl 	pm_s2ram_mark_check_and_clear
 	mov 	lr, r1
 	cmp     r0, #0x1
-	beq     resume
+	beq     .L_resume
 	bx      lr
 
-resume:
+.L_resume:
 	/*
 	 * Restore the CPU context
 	 */

arch/arm/core/cortex_m/swap_helper.S

@@ -98,7 +98,7 @@ SECTION_FUNC(TEXT, z_arm_pendsv)
 #ifdef CONFIG_FPU_SHARING
     /* Assess whether switched-out thread had been using the FP registers. */
     tst lr, #_EXC_RETURN_FTYPE_Msk
-    bne out_fp_endif
+    bne .L_out_fp_endif
 
     /* FP context active: set FP state and store callee-saved registers.
      * Note: if Lazy FP stacking is enabled, storing the callee-saved
@@ -108,7 +108,7 @@ SECTION_FUNC(TEXT, z_arm_pendsv)
     add r0, r2, #_thread_offset_to_preempt_float
     vstmia r0, {s16-s31}
 
-out_fp_endif:
+.L_out_fp_endif:
     /* At this point FPCCR.LSPACT is guaranteed to be cleared,
      * regardless of whether the thread has an active FP context.
      */
@@ -204,9 +204,9 @@ out_fp_endif:
      * were enabled before irq_lock was called.
      */
     cmp r0, #0
-    bne _thread_irq_disabled
+    bne .L_thread_irq_disabled
     cpsie i
-_thread_irq_disabled:
+.L_thread_irq_disabled:
 
 #if defined(CONFIG_MPU_STACK_GUARD) || defined(CONFIG_USERSPACE)
     /* Re-program dynamic memory map */
@@ -259,25 +259,25 @@ _thread_irq_disabled:
 #ifdef CONFIG_FPU_SHARING
     /* Assess whether switched-in thread had been using the FP registers. */
     tst lr, #_EXC_RETURN_FTYPE_Msk
-    beq in_fp_active
+    beq .L_in_fp_active
     /* FP context inactive for swapped-in thread:
      * - reset FPSCR to 0
      * - set EXC_RETURN.F_Type (prevents FP frame un-stacking when returning
      *   from pendSV)
      */
     movs.n r3, #0
     vmsr fpscr, r3
-    b in_fp_endif
+    b .L_in_fp_endif
 
-in_fp_active:
+.L_in_fp_active:
     /* FP context active:
      * - clear EXC_RETURN.F_Type
      * - FPSCR and caller-saved registers will be restored automatically
      * - restore callee-saved FP registers
      */
     add r0, r2, #_thread_offset_to_preempt_float
     vldmia r0, {s16-s31}
-in_fp_endif:
+.L_in_fp_endif:
     /* Clear CONTROL.FPCA that may have been set by FP instructions */
     mrs r3, CONTROL
     bic r3, #_CONTROL_FPCA_Msk
@@ -361,12 +361,12 @@ SECTION_FUNC(TEXT, z_arm_svc)
   movs r0, #_EXC_RETURN_SPSEL_Msk
   mov r1, lr
   tst r1, r0
-  beq _stack_frame_msp
+  beq .L_stack_frame_msp
   mrs r0, PSP
-  bne _stack_frame_endif
-_stack_frame_msp:
+  bne .L_stack_frame_endif
+.L_stack_frame_msp:
   mrs r0, MSP
-_stack_frame_endif:
+.L_stack_frame_endif:
 #elif defined(CONFIG_ARMV7_M_ARMV8_M_MAINLINE)
     tst lr, #_EXC_RETURN_SPSEL_Msk /* did we come from thread mode ? */
     ite eq  /* if zero (equal), came from handler mode */
@@ -399,7 +399,7 @@ _stack_frame_endif:
     mrs r2, CONTROL
 
     cmp r1, #3
-    beq _do_syscall
+    beq .L_do_syscall
 
     /*
      * check that we are privileged before invoking other SVCs
@@ -411,12 +411,12 @@ _stack_frame_endif:
 #elif defined(CONFIG_ARMV7_M_ARMV8_M_MAINLINE)
     tst r2, #0x1
 #endif
-    bne _oops
+    bne .L_oops
 
 #endif /* CONFIG_USERSPACE */
 
     cmp r1, #2
-    beq _oops
+    beq .L_oops
 
 #if defined(CONFIG_IRQ_OFFLOAD)
     push {r0, lr}
@@ -434,7 +434,7 @@ _stack_frame_endif:
 
 #endif
 
-_oops:
+.L_oops:
     push {r0, lr}
 #if defined(CONFIG_EXTRA_EXCEPTION_INFO)
 #if defined(CONFIG_ARMV7_M_ARMV8_M_MAINLINE)
@@ -484,7 +484,7 @@ _oops:
      * r6 - call_id
      * r8 - saved link register
      */
-_do_syscall:
+.L_do_syscall:
 #if defined(CONFIG_ARMV6_M_ARMV8_M_BASELINE)
     movs r3, #24
     ldr r1, [r0, r3]   /* grab address of PC from stack frame */
@@ -510,15 +510,15 @@ _do_syscall:
     /* The supplied syscall_id must be lower than the limit
      * (Requires unsigned integer comparison)
      */
-    blo valid_syscall_id
+    blo .L_valid_syscall_id
 
     /* bad syscall id.  Set arg1 to bad id and set call_id to SYSCALL_BAD */
     str r6, [r0]
     ldr r6, =K_SYSCALL_BAD
 
     /* Bad syscalls treated as valid syscalls with ID K_SYSCALL_BAD. */
 
-valid_syscall_id:
+.L_valid_syscall_id:
     ldr r0, =_kernel
     ldr r0, [r0, #_kernel_offset_to_current]
 #if defined(CONFIG_ARMV6_M_ARMV8_M_BASELINE)