ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault

Statuses 3 (0b00011) and 6 (0x00110) of DFSR are Access Flags faults on
ARMv6K and ARMv7. Let's patch fsr_info[] at runtime if we are on ARMv7
or later.

Unfortunately, we don't have runtime check for 'K' extension, so we
can't check for it.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 23 insertions, 2 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 77cfdbed9501..d073b64ae87e 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -926,8 +926,18 @@ static int __init alignment_init(void)
 
         hook_fault_code(1, do_alignment, SIGBUS, BUS_ADRALN,
                         "alignment exception");
-        hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
-                        "alignment exception");
+
+        /*
+         * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
+         * fault, not as alignment error.
+         *
+         * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
+         * needed.
+         */
+        if (cpu_architecture() <= CPU_ARCH_ARMv6) {
+                hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
+                                "alignment exception");
+        }
 
         return 0;
 }
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 5835e63454ff..23b0b03af5ea 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -607,6 +607,17 @@ static int __init exceptions_init(void)
                                 "I-cache maintenance fault");
         }
 
+        if (cpu_architecture() >= CPU_ARCH_ARMv7) {
+                /*
+                 * TODO: Access flag faults introduced in ARMv6K.
+                 * Runtime check for 'K' extension is needed
+                 */
+                hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
+                                "section access flag fault");
+                hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
+                                "section access flag fault");
+        }
+
         return 0;
 }