[PATCH 1/2] xen/arm: traps: report level 0 faults in panic_PAR()

decode_fsc() derives the fault level from the low two bits of the FSC, so
level 0 is a valid output: FSC_FLT_TRANS is 0x04, i.e. "translation fault,
level 0".

This is reachable on arm64 because xen_pgtable is the zeroeth-level root,
but fsc_level_str() has no case for it and prints " (level invalid)"
instead. At the time the function was created Xen used only three levels.

Add the missing case. On arm32 the zeroeth level does not exist, hence
guard the case by CONFIG_ARM_64.

While at it, make decode_fsc() decode also address size faults.

Signed-off-by: Michal Orzel <[email protected]>
---
 xen/arch/arm/include/asm/processor.h | 2 ++
 xen/arch/arm/traps.c                 | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/xen/arch/arm/include/asm/processor.h b/xen/arch/arm/include/asm/processor.h
index a3753c317fff..509040a1cdc0 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -521,6 +521,7 @@ extern register_t __cpu_logical_map[];
 /*
  * 543210 BIT
  * 00XXLL -- XX Fault Level LL
+ * ..00LL -- Address Size Fault LL
  * ..01LL -- Translation Fault LL
  * ..10LL -- Access Fault LL
  * ..11LL -- Permission Fault LL
@@ -534,6 +535,7 @@ extern register_t __cpu_logical_map[];
 #define FSC_TYPE_OTH   (_AC(0x02,U)<<4)
 #define FSC_TYPE_IMPL  (_AC(0x03,U)<<4)
 
+#define FSC_FLT_ADDR_SIZE (0x00)
 #define FSC_FLT_TRANS  (0x04)
 #define FSC_FLT_ACCESS (0x08)
 #define FSC_FLT_PERM   (0x0c)
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 0c01f37ad6b4..dc0ec8a345ed 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -307,6 +307,10 @@ static const char *decode_fsc(uint32_t fsc, int *level)
 
     switch ( fsc & 0x3f )
     {
+    case FSC_FLT_ADDR_SIZE ... FSC_FLT_ADDR_SIZE + 3:
+        msg = "Address size fault";
+        *level = fsc & FSC_LL_MASK;
+        break;
     case FSC_FLT_TRANS ... FSC_FLT_TRANS + 3:
         msg = "Translation fault";
         *level = fsc & FSC_LL_MASK;
@@ -363,6 +367,10 @@ static const char *fsc_level_str(int level)
     switch ( level )
     {
     case -1: return "";
+#ifdef CONFIG_ARM_64
+    /* On arm32 the zeroeth level does not exist */
+    case 0:  return " at level 0";
+#endif
     case 1:  return " at level 1";
     case 2:  return " at level 2";
     case 3:  return " at level 3";
-- 
2.43.0