Comment 11 for bug 947111

Here is a reference patch based on your previous one.
Both function do_t_mrs and do_t_msr need update.

diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 6ff64a6..7f69ffa 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -11201,8 +11201,14 @@ do_t_mrs (void)
       int flags = inst.operands[1].imm & (PSR_c|PSR_x|PSR_s|PSR_f|SPSR_BIT);

       if (ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_m))
- constraint (flags != 0, _("selected processor does not support "
- "requested special purpose register"));
+ {
+ /* PR gas/12698: The constraint is only applied for m_profile.
+ If the user has specified -march=all, we want to ignore it as
+ we are building for any CPU type, including non-m variants. */
+ bfd_boolean m_profile = selected_cpu.core != arm_arch_any.core;
+ constraint ((flags != 0) && m_profile, _("selected processor does "
+ "not support requested special purpose register"));
+ }
       else
  /* mrs only accepts APSR/CPSR/SPSR/CPSR_all/SPSR_all (for non-M profile
     devices). */
@@ -11235,11 +11241,14 @@ do_t_msr (void)
   if (ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_m))
     {
       int bits = inst.operands[0].imm & (PSR_c|PSR_x|PSR_s|PSR_f|SPSR_BIT);
-
- constraint ((ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_v6_dsp)
+ /* PR gas/12698: The constraint is only applied for m_profile.
+ If the user has specified -march=all, we want to ignore it as
+ we are building for any CPU type, including non-m variants. */
+ bfd_boolean m_profile = selected_cpu.core != arm_arch_any.core;
+ constraint (((ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_v6_dsp)
      && (bits & ~(PSR_s | PSR_f)) != 0)
     || (!ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_v6_dsp)
- && bits != PSR_f),
+ && bits != PSR_f)) && m_profile,
     _("selected processor does not support requested special "
       "purpose register"));
     }