Jacob Shin
2012-Oct-12 16:11 UTC
[PATCH] x86/xenoprof: Fix kernel/user mode detection for HVM
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@amd.com>
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);
}
Jan Beulich
2012-Oct-15 11:51 UTC
[PATCH, v2] 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@amd.com>
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@suse.com>
--- a/xen/arch/x86/oprofile/xenoprof.c
+++ b/xen/arch/x86/oprofile/xenoprof.c
@@ -74,16 +74,26 @@ int compat_oprof_arch_counter(XEN_GUEST_
return 0;
}
-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;
+ }
}
/*
--- a/xen/include/asm-x86/xenoprof.h
+++ b/xen/include/asm-x86/xenoprof.h
@@ -51,7 +51,7 @@ struct cpu_user_regs;
void ibs_init(void);
extern u32 ibs_caps;
-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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Keir Fraser
2012-Oct-15 12:09 UTC
Re: [PATCH, v2] x86/xenoprof: fix kernel/user mode detection for HVM
On 15/10/2012 12:51, "Jan Beulich" <JBeulich@suse.com> wrote:> 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@amd.com> > > 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@suse.com>Acked-by: Keir Fraser <keir@xen.org>> --- a/xen/arch/x86/oprofile/xenoprof.c > +++ b/xen/arch/x86/oprofile/xenoprof.c > @@ -74,16 +74,26 @@ int compat_oprof_arch_counter(XEN_GUEST_ > return 0; > } > > -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; > + } > } > > /* > --- a/xen/include/asm-x86/xenoprof.h > +++ b/xen/include/asm-x86/xenoprof.h > @@ -51,7 +51,7 @@ struct cpu_user_regs; > void ibs_init(void); > extern u32 ibs_caps; > > -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) > { > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel