| Message ID | 1424778380-28036-1-git-send-email-james.hogan@imgtec.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 24 Feb 2015 11:46:20 +0000 James Hogan <james.hogan@imgtec.com> wrote: > Lets save the actual PC in the structure so that the correct value is > accessible later. > > Fixes: 669e846e6c4e ("KVM/MIPS32: MIPS arch specific APIs for KVM") > Signed-off-by: James Hogan <james.hogan@imgtec.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Ralf Baechle <ralf@linux-mips.org> > Cc: Marcelo Tosatti <mtosatti@redhat.com> > Cc: Gleb Natapov <gleb@kernel.org> > Cc: Steven Rostedt <rostedt@goodmis.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> -- Steve > Cc: Ingo Molnar <mingo@redhat.com> > Cc: linux-mips@linux-mips.org > Cc: kvm@vger.kernel.org > Cc: <stable@vger.kernel.org> # v3.10+ > --- > arch/mips/kvm/trace.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Feb 24, 2015 at 11:46:20AM +0000, James Hogan wrote: > Currently the guest exit trace event saves the VCPU pointer to the > structure, and the guest PC is retrieved by dereferencing it when the > event is printed rather than directly from the trace record. This isn't > safe as the printing may occur long afterwards, after the PC has changed > and potentially after the VCPU has been freed. Usually this results in > the same (wrong) PC being printed for multiple trace events. It also > isn't portable as userland has no way to access the VCPU data structure > when interpreting the trace record itself. > > Lets save the actual PC in the structure so that the correct value is > accessible later. Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/mips/kvm/trace.h b/arch/mips/kvm/trace.h index c1388d40663b..bd6437f67dc0 100644 --- a/arch/mips/kvm/trace.h +++ b/arch/mips/kvm/trace.h @@ -24,18 +24,18 @@ TRACE_EVENT(kvm_exit, TP_PROTO(struct kvm_vcpu *vcpu, unsigned int reason), TP_ARGS(vcpu, reason), TP_STRUCT__entry( - __field(struct kvm_vcpu *, vcpu) + __field(unsigned long, pc) __field(unsigned int, reason) ), TP_fast_assign( - __entry->vcpu = vcpu; + __entry->pc = vcpu->arch.pc; __entry->reason = reason; ), TP_printk("[%s]PC: 0x%08lx", kvm_mips_exit_types_str[__entry->reason], - __entry->vcpu->arch.pc) + __entry->pc) ); #endif /* _TRACE_KVM_H */
Currently the guest exit trace event saves the VCPU pointer to the structure, and the guest PC is retrieved by dereferencing it when the event is printed rather than directly from the trace record. This isn't safe as the printing may occur long afterwards, after the PC has changed and potentially after the VCPU has been freed. Usually this results in the same (wrong) PC being printed for multiple trace events. It also isn't portable as userland has no way to access the VCPU data structure when interpreting the trace record itself. Lets save the actual PC in the structure so that the correct value is accessible later. Fixes: 669e846e6c4e ("KVM/MIPS32: MIPS arch specific APIs for KVM") Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Cc: <stable@vger.kernel.org> # v3.10+ --- arch/mips/kvm/trace.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)