[Xen-devel] [PATCH] x86/xenoprof: Fix kernel/user mode detection for HVM

[Jacob Shin <jacob.shin@xxxxxxx>]

x86/xenoprof: Fix kernel/user mode detection for HVM

While trying oprofile under Xen, I noticed that HVM passive domain's kernel 
addresses were showing up as user application. It turns out under HVM 
get_cpu_user_regs()->cs contains 0x0000beef.

Signed-off-by: Jacob Shin <jacob.shin@xxxxxxx>

diff -r e0e1350dfe9b xen/arch/x86/oprofile/xenoprof.c
--- a/xen/arch/x86/oprofile/xenoprof.c  Thu Oct 11 15:57:00 2012 +0100
+++ b/xen/arch/x86/oprofile/xenoprof.c  Fri Oct 12 10:48:37 2012 -0500
@@ -81,7 +81,11 @@ int xenoprofile_get_mode(const struct vc
         return 2;
 
     if ( is_hvm_vcpu(v) )
-        return ((regs->cs & 3) != 3);
+    {
+        struct segment_register cs;
+        hvm_get_segment_register((struct vcpu *)v, x86_seg_cs, &cs);
+        return ((cs.sel & 3) != 3);
+    }
 
     return guest_kernel_mode(v, regs);  
 }


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