• Milad Fa's avatar
    PPC/s390: [wasm][x64] Fix OSR shadow stack violation · 80aaae9e
    Milad Fa authored
    Port 06a2c2e0
    
    Original Commit Message:
    
        We currently allow OSR (On-Stack Replacement) of arbitrarily deep return
        addresses. This is in direct violation of Intel CET's shadow stack,
        which we plan to enable eventually.
    
        This change works around this by postponing OSR until after we return to
        the old code. The main changes are:
        - Reserve a slot in Liftoff frames to store the OSR target,
        - Skip the return address modification, and instead store the new code
        pointer in the dedicated slot,
        - Upon returning to the old code, check the slot and do an indirect jump
        to the new code if needed.
    
        CET also prevents indirect jumps to arbitrary locations, so the last
        point is also a CET violation. Valid indirect jump targets must be
        marked with the ENDBRANCH instruction, which I will do in a follow-up
        CL.
    
    R=thibaudm@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
    BUG=
    LOG=N
    
    Change-Id: Id972de1ba7556474cb00b377ea3a38eb4332eae3
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2828870Reviewed-by: 's avatarJunliang Yan <junyan@redhat.com>
    Commit-Queue: Milad Fa <mfarazma@redhat.com>
    Cr-Commit-Position: refs/heads/master@{#73984}
    80aaae9e
liftoff-assembler-ppc.h 69.8 KB