Module in_guest_site_patching 

The check that an in-guest Tool image runs with syscall site patching off, and collects the statistics it reports at exit, when the host asked for it (Config::in_guest_site_patching_off, set for hermit --backend=in-guest-trap).

The in-guest LiteInst runtime takes both settings from the guest environment while it installs the Tool: REVERIE_LITEINST_SITE_PATCHING and the statistics coordinator’s variable. Hermit sets them, but code that runs in the guest before the runtime’s constructor (a constructor of one of the program’s own shared libraries), or code the runtime calls through interposable symbols during installation, could change them. So the check does not read the environment: the Tool’s constructor records the host’s request, which arrived in the configuration handshake that guest code cannot change (require_site_patching_off), and once installation has returned the runtime’s preload constructor (detcore_liteinst_initialize) compares it with the settings the runtime actually captured and refuses to run the program when they differ (violation).

Functions

require_site_patching_off

Records that the host asked this Tool image to run with syscall site patching off and statistics on. Called from the Tool’s constructor.

site_patching_off_required

Whether the host asked this Tool image to run with syscall site patching off (require_site_patching_off).

violation

Why an image whose runtime captured runtime_patches (whether it patches syscall sites) and runtime_collects (whether it collects its exit statistics) breaks the host’s request, or None when it does not or when nothing was requested (required false).