sh: Support thread fault code encoding.

This provides a simple interface modelled after sparc64/m32r to encode
the error code in the upper byte of thread_info for finer-grained
handling in the page fault path.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 36 insertions, 10 deletions

diff --git a/arch/sh/include/asm/thread_info.h b/arch/sh/include/asm/thread_info.h
index 20ee40af16e9..25a13e534ffe 100644
--- a/arch/sh/include/asm/thread_info.h
+++ b/arch/sh/include/asm/thread_info.h
@@ -10,8 +10,18 @@
  *  - Incorporating suggestions made by Linus Torvalds and Dave Miller
  */
 #ifdef __KERNEL__
+
 #include <asm/page.h>
 
+/*
+ * Page fault error code bits
+ */
+#define FAULT_CODE_WRITE	(1 << 0)	/* write access */
+#define FAULT_CODE_INITIAL	(1 << 1)	/* initial page write */
+#define FAULT_CODE_ITLB		(1 << 2)	/* ITLB miss */
+#define FAULT_CODE_PROT		(1 << 3)	/* protection fault */
+#define FAULT_CODE_USER		(1 << 4)	/* user-mode access */
+
 #ifndef __ASSEMBLY__
 #include <asm/processor.h>
 
@@ -107,10 +117,13 @@ extern void init_thread_xstate(void);
 #endif /* __ASSEMBLY__ */
 
 /*
- * thread information flags
- * - these are process state flags that various assembly files may need to access
- * - pending work-to-be-done flags are in LSW
- * - other flags in MSW
+ * Thread information flags
+ *
+ * - Limited to 24 bits, upper byte used for fault code encoding.
+ *
+ * - _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or
+ *   we blow the tst immediate size constraints and need to fix up
+ *   arch/sh/kernel/entry-common.S.
  */
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_SIGPENDING		1	/* signal pending */
@@ -133,12 +146,6 @@ extern void init_thread_xstate(void);
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 
-/*
- * _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or we
- * blow the tst immediate size constraints and need to fix up
- * arch/sh/kernel/entry-common.S.
- */
-
 /* work to do in syscall trace */
 #define _TIF_WORK_SYSCALL_MASK	(_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
 				 _TIF_SYSCALL_AUDIT | _TIF_SECCOMP    | \
@@ -165,6 +172,7 @@ extern void init_thread_xstate(void);
 #define TS_USEDFPU		0x0002	/* FPU used by this task this quantum */
 
 #ifndef __ASSEMBLY__
+
 #define HAVE_SET_RESTORE_SIGMASK	1
 static inline void set_restore_sigmask(void)
 {
@@ -172,6 +180,24 @@ static inline void set_restore_sigmask(void)
 	ti->status |= TS_RESTORE_SIGMASK;
 	set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
 }
+
+#define TI_FLAG_FAULT_CODE_SHIFT	24
+
+/*
+ * Additional thread flag encoding
+ */
+static inline void set_thread_fault_code(unsigned int val)
+{
+	struct thread_info *ti = current_thread_info();
+	ti->flags = (ti->flags & (~0 >> (32 - TI_FLAG_FAULT_CODE_SHIFT)))
+		| (val << TI_FLAG_FAULT_CODE_SHIFT);
+}
+
+static inline unsigned int get_thread_fault_code(void)
+{
+	struct thread_info *ti = current_thread_info();
+	return ti->flags >> TI_FLAG_FAULT_CODE_SHIFT;
+}
 #endif	/* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */