[PATCH 4/5] ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault

[Kirill A. Shutsemov]

From: Kirill A. Shutemov <kirill at shutemov.name>

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 at shutemov.name>
---
 arch/arm/mm/alignment.c |   14 ++++++++++++--
 arch/arm/mm/fault.c     |   11 +++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 77cfdbe..d073b64 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 345a3c9..7e866e9 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -598,6 +598,17 @@ 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_MAPPERR,
+				"section access flag fault");
+		hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPPERR,
+				"section access flag fault");
+	}
+
 	return 0;
 }
 
-- 
1.7.1.1