• Igor Sheludko's avatar
    [ext-code-space] Fix CodeRange allocation logic · 695afbff
    Igor Sheludko authored
    1) when generating short builtin calls/jumps assemblers should use the
       offset from the CodeRange base rather than the start of the code
       range reservation because otherwise it's not guaranteed that the
       PC-relative offset will fit into architecture's constraints.
       The code range reservation start could be different from the code
       range base in the following cases:
         * when the "base bias size" is non-zero (on Windows 64),
         * when we ended up over-reserving the address space for the code
           range, which happens as a last resort to fulfil the CodeRange
           alignment requirements.
       See the VirtualMemoryCage description for details.
    
    Drive-by fixes:
    2) in case of over-reserving address space for external code range,
       the pre-calculated hint for where the remapped embedded builtins
       should be copied to was outside of the allocatable CodeRange region
       and thus useless. The fix is to use the allocatable region instead
       of the reservation region when calculating the hint.
    3) when allocating CodeRange with zero base bias size we can create
       the VirtualMemory reservation from the first attempt simply by
       passing the required base alignment to the VirtualMemory
       constructor.
    
    Bug: v8:11880, chromium:1290591
    Change-Id: If341418947e2170d967e22b38bcc371594939c1c
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3412089Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
    Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
    Commit-Queue: Igor Sheludko <ishell@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#78772}
    695afbff
assembler.cc 11.7 KB