[Xen-users] intercept and capture fast system call of linux

[韩艳东 <hanyandong@xxxxxxxxx>]

hi,

I want to intercept and capture fast  system call of linux. 

(1)I set GUEST_SYSENTER_EIP to   0xDDDDD0AE in vmx_vmexit_handler, and save the real value.

(2)When a fast syscall come,  I will caputue it in sh_page_fault.

(3) Then I set the real GUEST_SYSENTER_EIP(c0103ef0, ia32_sysenter_target) to GUEST_RIP.

But, I encounter Infinite loops as below. I always capture the same syscall.  

In sh_page_fault, I have successfully set c0103ef0 to GUEST_RIP.But I still capure a page fault , the GUEST_RIP is ddddd0ae.

why?

(XEN) MIT SYSCALL 7

(XEN) MITCTL: sh_page_fault syscall real_rip  ddddd0ae ddddd0ae   

(XEN) MITCTL: sh_page_fault syscall real_rip  ddddd0ae

(XEN) MITCTL: sh_page_fault syscall real_rip  c0103ef0

(XEN) MITCTL:vmx_set_sysenter_msrs GUEST_SYSENTER_EIP ddddd0ae 60

(XEN)  vmx_vmenter_helper MITCTL: sh_page_fault syscall real_rip  c0103ef0

(XEN) TRAP_page_fault

(XEN) MIT SYSCALL 7

(XEN) MITCTL: sh_page_fault syscall real_rip  ddddd0ae ddddd0ae

(XEN) MITCTL: sh_page_fault syscall real_rip  ddddd0ae

(XEN) MITCTL: sh_page_fault syscall real_rip  c0103ef0

(XEN) MITCTL:vmx_set_sysenter_msrs GUEST_SYSENTER_EIP ddddd0ae 60

(XEN)  vmx_vmenter_helper MITCTL: sh_page_fault syscall real_rip  c0103ef0

(XEN) TRAP_page_fault

(XEN) MIT SYSCALL 7

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