[Xen-changelog] [xen-4.2-testing] x86/xenoprof: fix kernel/user mode detection for HVM

[Xen patchbot-4.2-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Jacob Shin <jacob.shin@xxxxxxx>
# Date 1351171346 -7200
# Node ID cbb6326377bb99d10dc288a23a389273f3a7ffbc
# Parent  36fce7db3b3120b42ec60efad348c89dce4c4dcd
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>

Don't cast away const-ness. Use SS instead of CS to determine ring.
Special-case real and protected mode.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
xen-unstable changeset: 26055:14e32621dbaf
xen-unstable date: Mon Oct 15 13:04:51 UTC 2012
---


diff -r 36fce7db3b31 -r cbb6326377bb xen/arch/x86/oprofile/xenoprof.c
--- a/xen/arch/x86/oprofile/xenoprof.c  Thu Oct 25 15:21:01 2012 +0200
+++ b/xen/arch/x86/oprofile/xenoprof.c  Thu Oct 25 15:22:26 2012 +0200
@@ -78,16 +78,26 @@ int compat_oprof_arch_counter(XEN_GUEST_
 }
 #endif
 
-int xenoprofile_get_mode(const struct vcpu *v,
-                         const struct cpu_user_regs *regs)
+int xenoprofile_get_mode(struct vcpu *curr, const struct cpu_user_regs *regs)
 {
     if ( !guest_mode(regs) )
         return 2;
 
-    if ( is_hvm_vcpu(v) )
-        return ((regs->cs & 3) != 3);
+    if ( !is_hvm_vcpu(curr) )
+        return guest_kernel_mode(curr, regs);
 
-    return guest_kernel_mode(v, regs);  
+    switch ( hvm_guest_x86_mode(curr) )
+    {
+        struct segment_register ss;
+
+    case 0: /* real mode */
+        return 1;
+    case 1: /* vm86 mode */
+        return 0;
+    default:
+        hvm_get_segment_register(curr, x86_seg_ss, &ss);
+        return (ss.sel & 3) != 3;
+    }
 }
 
 /*
diff -r 36fce7db3b31 -r cbb6326377bb xen/include/asm-x86/xenoprof.h
--- a/xen/include/asm-x86/xenoprof.h    Thu Oct 25 15:21:01 2012 +0200
+++ b/xen/include/asm-x86/xenoprof.h    Thu Oct 25 15:22:26 2012 +0200
@@ -56,7 +56,7 @@ static inline void ibs_init(void) {}
 #define ibs_caps 0
 #endif
 
-int xenoprofile_get_mode(const struct vcpu *, const struct cpu_user_regs *);
+int xenoprofile_get_mode(struct vcpu *, const struct cpu_user_regs *);
 
 static inline int xenoprof_backtrace_supported(void)
 {

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