Add guard pages in front of platform allocations

Add guard pages in front of platform allocations

BUG=89247

[Cris Neckar, 2011-07-12 23:19:12]

On 2011/07/12 23:12:51, Cris Neckar wrote:

hold off on reviewing this. there is some cleanup to do in linux and mac

[Vyacheslav Egorov (Chromium), 2011-07-12 23:23:28]

Preliminary comments.

I still think that we should do that inside MemoryAllocator not inside OS.

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc
File src/platform-linux.cc (right):

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc#newcode373
src/platform-linux.cc:373: void* mbase = mmap(NULL, msize + Page::kPageSize,
prot,
V8 uses "one argument per line" convention.

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc#newcode382
src/platform-linux.cc:382: mbase += Page::kPageSize;
I am a bit concerned that we are spreading (and duplicating) guard page
management across platform-* files instead of managing it uniformly in the
MemoryAllocator which seems more appropriate place to me (OS::* should be just a
low-level OS interface).

http://codereview.chromium.org/7352007/diff/1/src/platform-win32.cc
File src/platform-win32.cc (right):

http://codereview.chromium.org/7352007/diff/1/src/platform-win32.cc#newcode916
src/platform-win32.cc:916: msize + Page::kPageSize,
This looks slightly suspicious to me.

MemoryAllocator knows about 64k allocation granularity on Windows and allocates
space for 8 8k Pages per call to OS::Allocate.

Here you basically ask for 8*8k + 8k which will waste 7*8k of VAS which
MemoryAllocator tried to avoid.

[Cris Neckar, 2011-07-14 17:32:28]

This new patch moves everything into MemoryAllocator as you suggested Slava.

Thanks!

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc
File src/platform-linux.cc (right):

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc#newcode373
src/platform-linux.cc:373: void* mbase = mmap(NULL, msize + Page::kPageSize,
prot,
On 2011/07/12 23:23:29, Vyacheslav Egorov wrote:
> V8 uses "one argument per line" convention.

Done.

http://codereview.chromium.org/7352007/diff/1/src/platform-linux.cc#newcode382
src/platform-linux.cc:382: mbase += Page::kPageSize;
On 2011/07/12 23:23:29, Vyacheslav Egorov wrote:
> I am a bit concerned that we are spreading (and duplicating) guard page
> management across platform-* files instead of managing it uniformly in the
> MemoryAllocator which seems more appropriate place to me (OS::* should be just
a
> low-level OS interface).

Done.

http://codereview.chromium.org/7352007/diff/1/src/platform-win32.cc
File src/platform-win32.cc (right):

http://codereview.chromium.org/7352007/diff/1/src/platform-win32.cc#newcode916
src/platform-win32.cc:916: msize + Page::kPageSize,
On 2011/07/12 23:23:29, Vyacheslav Egorov wrote:
> This looks slightly suspicious to me.
> 
> MemoryAllocator knows about 64k allocation granularity on Windows and
allocates
> space for 8 8k Pages per call to OS::Allocate.
> 
> Here you basically ask for 8*8k + 8k which will waste 7*8k of VAS which
> MemoryAllocator tried to avoid.

Done.

[Cris Neckar, 2011-07-14 19:10:51]

This is replaced by http://codereview.chromium.org/7379004/