• eholk's avatar
    [wasm] Initial signal handler · 118c376f
    eholk authored
    This is basically the minimum viable signal handler for Wasm bounds checks.
    It includes the TLS check and the fine grained instructions checks. These
    two checks provide most of the safety for the signal handler. Future CLs will
    add code range and data range checks for more robustness.
    
    The trap handling code and data structures are all in src/trap-handler, with
    the code that actually runs in the signal handler confined to
    src/trap-handler/signal-handler.cc.
    
    This changes adds a new V8 API that the embedder should call from a signal
    handler that will give V8 the chance to handle the fault first. For hosts that
    do not want to implement their own signal handler, we include the option to
    install a simple one. This simple handler is also used for the tests.
    
    When a Wasm module is instantiated, information about each function is passed
    to the trap handler, which is used to classify faults. These are removed during
    the instance finalizer.
    
    Several future enhancements are planned before turning this on by default.
    Obviously, the additional checks will be added to MaybeHandleFault. We are
    also planning to add a two-level CodeObjectData table that is grouped by
    isolates to make cleanup easier and also reduce potential for contending on
    a single data structure.
    
    BUG= https://bugs.chromium.org/p/v8/issues/detail?id=5277
    
    Review-Url: https://codereview.chromium.org/2371833007
    Cr-Original-Original-Commit-Position: refs/heads/master@{#43523}
    Committed: https://chromium.googlesource.com/v8/v8/+/a5af7fe9ee388a636675f4a6872b1d34fa7d1a7a
    Review-Url: https://codereview.chromium.org/2371833007
    Cr-Original-Commit-Position: refs/heads/master@{#43755}
    Committed: https://chromium.googlesource.com/v8/v8/+/338622d7cae787a63cece1f2e79a8b030023940b
    Review-Url: https://codereview.chromium.org/2371833007
    Cr-Commit-Position: refs/heads/master@{#43759}
    118c376f
factory.cc 106 KB