ltp: we can support exec like syscall

[Martins3]

Although dune can't make the program which is a parameter of syscall exec run in a virtualization environment, making the program run correctly without too many limitations is always better.

[Martins3]

• [x] what's the difference between this syscall?
• [x] should I close the kvm related file descriptors?
  • [x] close-on-exec?
  • [x] close manually?

[Martins3]

One way to do that is to always open files using the flag O_CLOEXEC, which ensures that this file descriptor is automatically closed when exec...() is ever called. [^1]

1. https://stackoverflow.com/questions/56650579/why-should-i-close-all-file-descriptors-after-calling-fork-and-prior-to-callin

[Martins3]

• [x] Why Linux doesn't close the file descriptor automatically when exec?

[Martins3]

• [x] https://stackoverflow.com/questions/5429141/what-happens-to-malloced-memory-after-exec-changes-the-program-image

All the memory freed, that's what we expected.

• [x] https://stackoverflow.com/questions/9583845/why-isnt-close-on-exec-the-default-configuration

[Martins3]

https://stackoverflow.com/questions/6125068/what-does-the-fd-cloexec-fcntl-flag-do

• [x] so, I should fnctl all the flags, then everything is fine ?
• [x] take care of the sequential?

[Martins3]

• [x] uselib syscall ?

MIPS doesn't use it.

[Martins3]

• kvm_vcpu_release
• kvm_device_release
• kvm_vm_release

These function called by KVM module, they should be carefully called properly.

[Martins3]

It works.