[PATCH 4/5] x86/fixmap: add a predicate for usermode fixmaps

[Jeremy Fitzhardinge]

Some set of fixmaps are intented to be mapped into usermode.  Add an
predicate to test for those fixmaps.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/include/asm/fixmap.h |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index ff3cffa..0edc2bb 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -181,6 +181,24 @@ static inline void __set_fixmap(enum fixed_addresses idx,
 
 extern void __this_fixmap_does_not_exist(void);
 
+static inline bool user_fixmap(enum fixed_addresses fixmap)
+{
+	switch (fixmap) {
+#ifdef CONFIG_X86_32
+	case FIX_HOLE ... FIX_VDSO:
+#else
+	case VSYSCALL_LAST_PAGE ... VSYSCALL_HPET:
+#ifdef CONFIG_PARAVIRT_CLOCK_VSYSCALL
+	case FIX_PVCLOCK_TIME_INFO:
+#endif
+#endif
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 /*
  * 'index to address' translation. If anyone tries to use the idx
  * directly without translation, we catch the bug with a NULL-deference
-- 
1.6.2.5

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