[PATCH v6 07/19] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat)

On Fri, Dec 04, 2015 at 08:05:23PM +0300, Yury Norov wrote:

On Thu, Dec 03, 2015 at 12:13:03PM +0000, Catalin Marinas wrote:

quoted

On Wed, Nov 18, 2015 at 12:16:47AM +0300, Yury Norov wrote:

quoted

diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
index 7fbed69..9700e5e 100644
--- a/arch/arm64/include/asm/compat.h
+++ b/arch/arm64/include/asm/compat.h

@@ -299,19 +299,44 @@ struct compat_shmid64_ds {
 	compat_ulong_t __unused5;
 };
 
-static inline int is_compat_task(void)
+#ifdef CONFIG_AARCH32_EL0
+
+static inline int is_a32_compat_task(void)
 {
 	return test_thread_flag(TIF_32BIT);
 }
 
-static inline int is_compat_thread(struct thread_info *thread)
+static inline int is_a32_compat_thread(struct thread_info *thread)
 {
 	return test_ti_thread_flag(thread, TIF_32BIT);
 }
 
+#else
+
+static inline int is_a32_compat_task(void)
+{
+	return 0;
+}
+
+static inline int is_a32_compat_thread(struct thread_info *thread)
+{
+	return 0;
+}
+#endif
+
+static inline int is_compat_task(void)
+{
+	return is_a32_compat_task();
+}
+
 #else /* !CONFIG_COMPAT */
 
-static inline int is_compat_thread(struct thread_info *thread)
+static inline int is_a32_compat_thread(struct thread_info *thread)
+{
+	return 0;
+}
+
+static inline int is_a32_compat_task(void)
 {
 	return 0;
 }

My main worry with this patch is a potential #include mess. I can see
that you already had to include asm/compat.h explicitly in
hw_breakpoint.c even though linux/compat.h was already included. In
subsequent files (asm/elf.h, asm/memory.h) you check is_compat_task()
without explicitly including asm/compat.h and hope that it won't break.

A solution would be to add these functions in a separate header file
that gets included where needed (also by asm/compat.h).

Thank you for pointing that. I don't see big advantage in moving that
to new file, only if you insist. What about just fixing that mess?

As I said above, you use is_compat_task() in asm/elf.h for example
without including asm/compat.h. At some point, you may get a build error
in some unrelated C file. You could wait until it happens and then sort
it out (by either including asm/compat.h in asm/elf.h or creating a new
header file). My preference is to prevent such build errors early.

-- 
Catalin