Ok after discovering for several days i find out the real working code is not here, but in base/allocator/partition_allocator/src/partition_alloc/page_allocator_internals_posix.h, but why there are so much complete logics and code in src/v8 but some logical branch is never reached?
在2024年2月2日星期五 UTC+8 16:15:11<chen chang> 写道： > What I know or, understand the mechanic: > > I know that ARM based Apple Silicon(I call it M1 in following) doesn't > allow applications apply RWX memorys, so that v8 flag the codespace with > kNoAccessWillJitLater, in which way when calling mmap(), the MAP_JIT bit is > set, so that compiler can switch the memory between RW and RX. I try to > borrow the method in my own project, so I change the code in > v8/src/base/page-allocator.cc:47, where restrict the flag only work in M1 > environment. > > There are only two places where JitLater is used as param: > v8/src/utils/allocation.cc:221 > v8/src/heap/code-range.cc:365 > and both of them call page_allocator->AllocatePages() > > but PageAllocator is a class with 5 different subclass, since in > v8/src/base/page-allocator.cc v8 block the JitLater in not-M1 system(I > remove the block, it is not its fault, I also change the logic where > judging access in platform-posix.cc GetFlagsForMemoryPermisson()), I > thought it is where the call really goes. > And I write my code in v8/scr/base/platform/platform-posix.cc(I develop in > linux), and listen in linux kernel, expecting browser make mmap() request > with flag which has MAP_JIT bit, but no answer is got. > > Potential answer: the caller is caling with other classes but not > subclass in src/base/page-allocator, but i figure this deeper need lots of > time. > > Hope someone can help me with this problem, after removing two bypassing > about kNoAccessWillJitLater, why cant see my change in kernel log？ > P.S. not sys/mman.h and MAP_JIT fault, i test it with fixed bit. > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/2c7ddee5-9a61-474c-a194-3a489543d9e1n%40googlegroups.com.
