Currently every VirtualMemory allocation on 64-bit systems
uses a random 46-bit address hint for ASLR.
This leads to wired page leak on MacOS discovered by Erik Chen (see
crbug.com/700928 and https://chromium-review.googlesource.com/c/557958/):
"The Darwin kernel [as of macOS 10.12.5] does not clean up page directory
entries [PDE] created from mmap or mach_vm_allocate, even after
the region is destroyed. Using a virtual address space that is too large
causes a leak of about 1 wired [can never be paged out] page per call to
mmap(). The page is only reclaimed when the process is killed."
This patch changes VirtualMemory to accept the hint parameter explicitly.
On MacOS the hints are confined to 4GB contiguous region. Algorithm:
- On startup, set heap.mmap_region_base_ to a random address.
- For each mmap use heap.mmap_region_base_ + (random_offset % (4*GB)).
BUG=chromium:700928
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I2ae6a024e02fbe63f940105d7920b57c19abacc6
Reviewed-on: https://chromium-review.googlesource.com/558876
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46656}
Original descriptions were:
- "Refactor and cleanup VirtualMemory."
- "Fix typo."
- "Deuglify V8_INLINE and V8_NOINLINE."
- "Don't align size on allocation granularity for unaligned ReserveRegion calls."
Reasons for the revert are:
- Our mjsunit test suite slower by a factor of 5(!) in release mode.
- Flaky cctest/test-alloc/CodeRange on all architectures and platforms.
- Tankage of Sunspider by about 6% overall (unverified).
TBR=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/23970004
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16662 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove a lot of platform duplication, and simplify the virtual
memory implementation. Also improve readability by avoiding bool
parameters for executability (use a dedicated Executability type
instead).
Get rid of the Isolate::UncheckedCurrent() call in the platform
code, as part of the Isolate TLS cleanup.
Use a dedicated random number generator for the address
randomization, instead of messing with the per-isolate random
number generators.
TEST=cctest/test-virtual-memory
R=verwaest@chromium.org
Review URL: https://codereview.chromium.org/23641009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16637 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The RandomNumberGenerator is a pseudorandom number generator
with 48-bit state. It is properly seeded using either
(1) the --random-seed if specified, or
(2) the entropy_source function if configured, or
(3) /dev/urandom if available, or
(4) falls back to Time and TimeTicks based seeding.
Each Isolate now contains a RandomNumberGenerator, which replaces
the previous private_random_seed.
Every native context still has its own random_seed. But this random
seed is now properly initialized during bootstrapping,
instead of on-demand initialization. This will allow us to cleanup
and speedup the HRandom implementation quite a lot (this is delayed
for a followup CL)!
Also stop messing with the system rand()/random(), which should
not be done from a library anyway! We probably re-seeded the
libc rand()/random() after the application (i.e. Chrome) already
seeded it (with better entropy than what we used).
Another followup CL will replace the use of the per-isolate
random number generator for the address randomization and
thereby get rid of the Isolate::UncheckedCurrent() usage in
the platform code.
TEST=cctest/test-random-number-generator,cctest/test-random
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23548024
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16612 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Condition variables are synchronization primitives that can be used
to block one or more threads while waiting for condition to become
true.
Right now we have only semaphores, mutexes and atomic operations for
synchronization, which results in quite complex solutions where an
implementation using condition variables and mutexes would be straight
forward.
There's also a performance benefit to condition variables and mutexes
vs semaphores, especially on Windows, where semaphores are kernel
objects, while mutexes are implemented as fast critical sections,
it CAN be beneficial performance-wise to use condition variables
instead of semaphores.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23548007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Drop the previous Mutex and ScopedLock classes from platform files.
Add new Mutex, RecursiveMutex and LockGuard classes, which are
designed after their C++11 counterparts, so that at some point
we can simply drop our custom code and switch to the C++11
classes. We distinguish regular and recursive mutexes, as the
latter don't work well with condition variables, which will be
introduced by a followup CL.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23625003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16416 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
In the shell sample don't print the result of executing a script, only
evaluating expressions.
Fixed issue when building samples on Windows using a shared V8
library. Added visibility option on Linux build which makes the
generated library 18% smaller.
Changed build system to accept multiple build modes in one build and
generate seperate objects, libraries and executables for each mode.
Removed deferred negation optimization (a * -b => -(a * b)) since this
visibly changes operand conversion order.
Improved parsing performance by introducing stack guard in preparsing.
Without a stack guard preparsing always bails out with stack overflow.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
