• Michael Achenbach's avatar
    Revert "[wasm] Add PKU alloc/free and support counter" · f98f496f
    Michael Achenbach authored
    This reverts commit a4c37558.
    
    Reason for revert: Speculative revert.
    Seems to break all gpu builders, e.g.:
    https://ci.chromium.org/p/v8/builders/ci/Linux%20V8%20FYI%20Release%20(NVIDIA)/14577
    
    See shards for detailed output, e.g.:
    https://chromium-swarm.appspot.com/task?id=534a8fbeaca4df10
    
    Check failed: valid_arguments. V8.WasmMemoryProtectionKeysSupport
    
    Original change's description:
    > [wasm] Add PKU alloc/free and support counter
    >
    > To enforce W^X for the WebAssembly code space, we want to explore using
    > Intel memory protection keys for userspace, also known as MPK, PKEYs, or
    > PKU. Instead of flipping page protection flags with mprotect (which
    > incurs a high syscall overhead; and which switches flags for the whole
    > process), this associates a key with each page once, and then changes
    > the permissions of that key with a fast thread-local register write.
    > That is, this gives both finger-grained permissions (per-thread) and
    > more performance.
    >
    > This CL is starts experimenting with PKUs by
    > (1) trying to allocate a protection key once per {WasmEngine} in x64
    > Linux systems, and
    > (2) adding a counter for recording the sucess/failure of that, to assess
    > the support for PKUs on the target machine.
    >
    > The low-level PKU allocating functions should be moved into base/platform
    > long-term, but are inside wasm/ for this CL.
    >
    > R=​clemensb@chromium.org
    > CC=​​jkummerow@chromium.org
    >
    > Bug: v8:11714
    > Change-Id: Ia4858970ced4d0b84cc8c2651e86dceb532c88a7
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2850932
    > Commit-Queue: Daniel Lehmann <dlehmann@google.com>
    > Reviewed-by: Clemens Backes <clemensb@chromium.org>
    > Cr-Commit-Position: refs/heads/master@{#74319}
    
    Bug: v8:11714
    Change-Id: I70349d413ac9092e2f033d138887678bfecaae17
    No-Presubmit: true
    No-Tree-Checks: true
    No-Try: true
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2868607
    Auto-Submit: Michael Achenbach <machenbach@chromium.org>
    Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
    Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
    Cr-Commit-Position: refs/heads/master@{#74339}
    f98f496f
counters-definitions.h 25.4 KB