Summary:
Few changes to the secondary:
- mark `const` variables as such;
- change some `CHECK` to `DCHECK`: I don't feel we need to be as conservative as
we were with out checks, as they are the results of our own computation.
- mark a condition as `UNLIKELY`.
Reviewers: alekseyshl
Reviewed By: alekseyshl
Subscribers: delcypher, #sanitizers, llvm-commits
Differential Revision: https://reviews.llvm.org/D42696
llvm-svn: 323997
Summary:
This wasn't noticed: `RoundUpTo` doesn't produce a constant expression, so the
sizes were not constant either. Enforce them to be static const, replace
`RoundUpTo` by its expression. The compiler can now optimize the associated
computations accordingly.
Also looking at the produced assembly, `PageSize` was fetched multiple times
during `Allocate`, so keep a local value of it. As a result it's fetched once
and kept in a register.
Reviewers: alekseyshl, flowerhack
Reviewed By: alekseyshl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D40862
llvm-svn: 319903
Summary:
The ScudoAllocator uses a SecondaryHeader to keep track of the size and base address of each mmap'd chunk.
This aligns well with what the ReservedAddressRange is trying to do. This changeset converts the scudo allocator from using the MmapNoAccess/MmapFixed APIs to the ReservedAddressRange::Init and ::Map APIs. In doing so, it replaces the SecondayHeader struct with the ReservedAddressRange object.
This is part 3 of a 4 part changeset; part 1 https://reviews.llvm.org/D39072 and part 2 https://reviews.llvm.org/D38592
Reviewers: alekseyshl, mcgrathr, cryptoad, phosek
Reviewed By: cryptoad
Subscribers: llvm-commits, cryptoad, kubamracek
Differential Revision: https://reviews.llvm.org/D38593
llvm-svn: 318080
Summary:
Scudo abides by the coding style enforced by the sanitizer_common
linter, but as of right now, it's not linter-enforced.
Add Scudo to the list of directories checked by check_lint.sh.
Also: fixes some linter errors found after getting this running.
Reviewers: cryptoad
Reviewed By: cryptoad
Subscribers: llvm-commits, kubamracek
Differential Revision: https://reviews.llvm.org/D39757
llvm-svn: 317699
Summary:
Move cached allocator_may_return_null flag to sanitizer_allocator.cc and
provide API to consolidate and unify the behavior of all specific allocators.
Make all sanitizers using CombinedAllocator to follow
AllocatorReturnNullOrDieOnOOM() rules to behave the same way when OOM
happens.
When OOM happens, turn allocator_out_of_memory flag on regardless of
allocator_may_return_null flag value (it used to not to be set when
allocator_may_return_null == true).
release_to_os_interval_ms and rss_limit_exceeded will likely be moved to
sanitizer_allocator.cc too (later).
Reviewers: eugenis
Subscribers: srhines, kubamracek, llvm-commits
Differential Revision: https://reviews.llvm.org/D34310
llvm-svn: 305858
Summary:
The reasoning behind this change is twofold:
- the current combined allocator (sanitizer_allocator_combined.h) implements
features that are not relevant for Scudo, making some code redundant, and
some restrictions not pertinent (alignments for example). This forced us to
do some weird things between the frontend and our secondary to make things
work;
- we have enough information to be able to know if a chunk will be serviced by
the Primary or Secondary, allowing us to avoid extraneous calls to functions
such as `PointerIsMine` or `CanAllocate`.
As a result, the new scudo-specific combined allocator is very straightforward,
and allows us to remove some now unnecessary code both in the frontend and the
secondary. Unused functions have been left in as unimplemented for now.
It turns out to also be a sizeable performance gain (3% faster in some Android
memory_replay benchmarks, doing some more on other platforms).
Reviewers: alekseyshl, kcc, dvyukov
Reviewed By: alekseyshl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33007
llvm-svn: 302830
Summary:
This is part of D31947 that is being split into several smaller changes.
This one deals with all the minor changes, more specifically:
- Rename some variables and functions to make their purpose clearer;
- Reorder some code;
- Mark the hot termination incurring checks as `UNLIKELY`; if they happen, the
program will die anyway;
- Add a `getScudoChunk` method;
- Add an `eraseHeader` method to ScudoChunk that will clear a header with 0s;
- Add a parameter to `allocate` to know if the allocated chunk should be filled
with zeros. This allows `calloc` to not have to call
`GetActuallyAllocatedSize`; more changes to get rid of this function on the
hot paths will follow;
- reallocate was missing a check to verify that the pointer is properly
aligned on `MinAlignment`;
- The `Stats` in the secondary have to be protected by a mutex as the `Add`
and `Sub` methods are actually not atomic;
- The software CRC32 function was moved to the header to allow for inlining.
Reviewers: dvyukov, alekseyshl, kcc
Reviewed By: dvyukov
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32242
llvm-svn: 300846
Summary:
I atually had an integer overflow on 32-bit with D27428 that didn't reproduce
locally, as the test servers would manage allocate addresses in the 0xffffxxxx
range, which led to some issues when rounding addresses.
At this point, I feel that Scudo could benefit from having its own combined
allocator, as we don't get any benefit from the current one, but have to work
around some hurdles (alignment checks, rounding up that is no longer needed,
extraneous code).
Reviewers: kcc, alekseyshl
Subscribers: llvm-commits, kubabrecka
Differential Revision: https://reviews.llvm.org/D27681
llvm-svn: 289572
Summary:
The combined allocator rounds up the requested size with regard to the
alignment, which makes sense when being serviced by the primary as it comes
with alignment guarantees, but not with the secondary. For the rare case of
large alignments, it wastes memory, and entices unnecessarily large fields for
the Scudo header. With this patch, we pass the non-alignement-rounded-up size
to the secondary, and adapt the Scudo code for this change.
Reviewers: alekseyshl, kcc
Subscribers: llvm-commits, kubabrecka
Differential Revision: https://reviews.llvm.org/D27428
llvm-svn: 289088
Summary:
This update introduces i386 support for the Scudo Hardened Allocator, and
offers software alternatives for functions that used to require hardware
specific instruction sets. This should make porting to new architectures
easier.
Among the changes:
- The chunk header has been changed to accomodate the size limitations
encountered on 32-bit architectures. We now fit everything in 64-bit. This
was achieved by storing the amount of unused bytes in an allocation rather
than the size itself, as one can be deduced from the other with the help
of the GetActuallyAllocatedSize function. As it turns out, this header can
be used for both 64 and 32 bit, and as such we dropped the requirement for
the 128-bit compare and exchange instruction support (cmpxchg16b).
- Add 32-bit support for the checksum and the PRNG functions: if the SSE 4.2
instruction set is supported, use the 32-bit CRC32 instruction, and in the
XorShift128, use a 32-bit based state instead of 64-bit.
- Add software support for CRC32: if SSE 4.2 is not supported, fallback on a
software implementation.
- Modify tests that were not 32-bit compliant, and expand them to cover more
allocation and alignment sizes. The random shuffle test has been deactivated
for linux-i386 & linux-i686 as the 32-bit sanitizer allocator doesn't
currently randomize chunks.
Reviewers: alekseyshl, kcc
Subscribers: filcab, llvm-commits, tberghammer, danalbert, srhines, mgorny, modocache
Differential Revision: https://reviews.llvm.org/D26358
llvm-svn: 288255
Summary:
In order to support 32-bit platforms, we have to make some adjustments in
multiple locations, one of them being the Scudo chunk header. For it to fit on
64 bits (as a reminder, on x64 it's 128 bits), I had to crunch the space taken
by some of the fields. In order to keep the offset field small, the secondary
allocator was changed to accomodate aligned allocations for larger alignments,
hence making the offset constant for chunks serviced by it.
The resulting header candidate has been added, and further modifications to
allow 32-bit support will follow.
Another notable change is the addition of MaybeStartBackgroudThread() to allow
release of the memory to the OS.
Reviewers: kcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D25688
llvm-svn: 285209
Summary:
s/CHECK_LT/CHECK_LE/ in the secondary allocator, as under certain circumstances
Ptr + Size can be equal to MapEnd. This edge case was not found by the current
tests, so those were extended to be able to catch that.
Reviewers: kcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D25101
llvm-svn: 282913
Summary:
GetActuallyAllocatedSize() was not accounting for the last page of the mapping
being a guard page, and was returning the wrong number of actually allocated
bytes, which in turn would mess up with the realloc logic. Current tests didn't
find this as the size exercised was only serviced by the Primary.
Correct the issue by subtracting PageSize, and update the realloc test to
exercise paths in both the Primary and the Secondary.
Reviewers: kcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24787
llvm-svn: 282030
Summary:
The Sanitizer Secondary Allocator was not entirely ideal was Scudo for several
reasons: decent amount of unneeded code, redundant checks already performed by
the front end, unneeded data structures, difficulty to properly protect the
secondary chunks header.
Given that the second allocator is pretty straight forward, Scudo will use its
own, trimming all the unneeded code off of the Sanitizer one. A significant
difference in terms of security is that now each secondary chunk is preceded
and followed by a guard page, thus mitigating overflows into and from the
chunk.
A test was added as well to illustrate the overflow & underflow situations
into the guard pages.
Reviewers: kcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24737
llvm-svn: 281938
Kostya Kortchinsky