Use proper llvm-target for armv7

arm-unknown-linux-gnueabihf was incorrectly used as llvm-target instead
of armv7-unknown-linux-gnueabihf when building for some Cortex A SoCs.
This may cause segfaults in non trivial rust applications on ARMv7
when e.g. +a7 is passed to LLVM. It seems to differ between different
versions of the compiler and LLVM versions.

classes/rust-common.bbclass

@@ -31,6 +31,24 @@ def determine_libc(d, thing):
 
     return libc
 
+def target_is_armv7(d):
+    '''Determine if target is armv7'''
+    # TUNE_FEATURES may include arm* even if the target is not arm
+    # in the case of *-native packages
+    if d.getVar('TARGET_ARCH') != 'arm':
+        return False
+
+    feat = d.getVar('TUNE_FEATURES')
+    feat = frozenset(feat.split())
+    mach_overrides = d.getVar('MACHINEOVERRIDES')
+    mach_overrides = frozenset(mach_overrides.split(':'))
+
+    v7=frozenset(['armv7a', 'armv7r', 'armv7m', 'armv7ve'])
+    if mach_overrides.isdisjoint(v7) and feat.isdisjoint(v7):
+        return False
+    else:
+        return True
+
 # Responsible for taking Yocto triples and converting it to Rust triples
 def rust_base_triple(d, thing):
     '''
@@ -40,7 +58,12 @@ def rust_base_triple(d, thing):
     Note that os is assumed to be some linux form
     '''
 
-    arch = d.getVar('{}_ARCH'.format(thing))
+    # The llvm-target for armv7 is armv7-unknown-linux-gnueabihf
+    if thing == "TARGET" and target_is_armv7(d):
+        arch = "armv7"
+    else:
+        arch = d.getVar('{}_ARCH'.format(thing))
+
     # All the Yocto targets are Linux and are 'unknown'
     vendor = "-unknown"
     os = d.getVar('{}_OS'.format(thing))

recipes-devtools/rust/rust.inc

@@ -72,9 +72,9 @@ def llvm_features_from_tune(d):
     if 'mips32r2' in feat:
         f.append("+mips32r2")
 
-    v7=frozenset(['armv7a', 'armv7r', 'armv7m', 'armv7ve'])
-    if (not mach_overrides.isdisjoint(v7)) or (not feat.isdisjoint(v7)):
-        f.append("+v7")
+    if target_is_armv7(d):
+        f.append('+v7')
+
     if ('armv6' in mach_overrides) or ('armv6' in feat):
         f.append("+v6")
 
@@ -83,8 +83,8 @@ def llvm_features_from_tune(d):
 
     if 'thumb' in feat:
         if d.getVar('ARM_THUMB_OPT') is "thumb":
-            if (not mach_overrides.isdisjoint(v7)) or (not feat.isdisjoint(v7)):
-                f.append("+thumb2")
+            if target_is_armv7(d):
+                f.append('+thumb2')
             f.append("+thumb-mode")
 
     if 'cortexa5' in feat:
@@ -154,6 +154,15 @@ TARGET_C_INT_WIDTH[arm] = "32"
 MAX_ATOMIC_WIDTH[arm] = "64"
 FEATURES[arm] = "+v6,+vfp2"
 
+## armv7-unknown-linux-gnueabihf
+DATA_LAYOUT[armv7] = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+LLVM_TARGET[armv7] = "${RUST_TARGET_SYS}"
+TARGET_ENDIAN[armv7] = "little"
+TARGET_POINTER_WIDTH[armv7] = "32"
+TARGET_C_INT_WIDTH[armv7] = "32"
+MAX_ATOMIC_WIDTH[armv7] = "64"
+FEATURES[armv7] = "+v7,+vfp2,+thumb2"
+
 ## aarch64-unknown-linux-{gnu, musl}
 DATA_LAYOUT[aarch64] = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 LLVM_TARGET[aarch64] = "${RUST_TARGET_SYS}"
@@ -243,7 +252,10 @@ TARGET_C_INT_WIDTH[riscv64] = "64"
 MAX_ATOMIC_WIDTH[riscv64] = "64"
 
 def arch_for(d, thing):
-    return d.getVar('{}_ARCH'.format(thing))
+    if thing == 'TARGET' and target_is_armv7(d):
+        return "armv7"
+    else:
+        return d.getVar('{}_ARCH'.format(thing))
 
 def sys_for(d, thing):
     return d.getVar('{}_SYS'.format(thing))
@@ -260,6 +272,8 @@ def arch_to_rust_target_arch(arch):
         return "mips"
     elif arch == "mip64sel":
         return "mips64"
+    elif arch == "armv7":
+        return "arm"
     else:
         return arch