Export the 'vsyscall' address to user space with the AT_SYSINFO

elf AUX-table entry.

Move the 'vsyscall' page to 0xffffe000, leaving a hole at the top
of the address space.

arch/i386/kernel/entry.S

@@ -232,7 +232,7 @@ need_resched:
 #endif
 
 /* Points to after the "sysenter" instruction in the vsyscall page */
-#define SYSENTER_RETURN 0xfffff007
+#define SYSENTER_RETURN 0xffffe007
 
 	# sysenter call handler stub
 	ALIGN

include/asm-i386/elf.h

@@ -100,6 +100,12 @@ typedef struct user_fxsr_struct elf_fpxregset_t;
 
 #define ELF_PLATFORM  (system_utsname.machine)
 
+/*
+ * Architecture-neutral AT_ values in 0-17, leave some room
+ * for more of them, start the x86-specific ones at 32.
+ */
+#define AT_SYSINFO	32
+
 #ifdef __KERNEL__
 #define SET_PERSONALITY(ex, ibcs2) set_personality((ibcs2)?PER_SVR4:PER_LINUX)
 
@@ -116,6 +122,11 @@ extern void dump_smp_unlazy_fpu(void);
 #define ELF_CORE_SYNC dump_smp_unlazy_fpu
 #endif
 
+#define ARCH_DLINFO					\
+do {							\
+		NEW_AUX_ENT(AT_SYSINFO, 0xffffe000);	\
+} while (0)
+
 #endif
 
 #endif

include/asm-i386/fixmap.h

@@ -42,8 +42,8 @@
  * task switches.
  */
 enum fixed_addresses {
-	FIX_VSYSCALL,
 	FIX_HOLE,
+	FIX_VSYSCALL,
 #ifdef CONFIG_X86_LOCAL_APIC
 	FIX_APIC_BASE,	/* local (CPU) APIC) -- required for SMP or not */
 #endif