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path: root/Kernel/VM/Region.cpp
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2021-08-06Kernel: Rename Kernel/VM/ to Kernel/Memory/Andreas Kling
This directory isn't just about virtual memory, it's about all kinds of memory management.
2021-07-25Kernel: Remove unnecessary counting of VMObject-attached RegionsAndreas Kling
VMObject already has an IntrusiveList of all the Regions that map it. We were keeping a counter in addition to this, and only using it in a single place to avoid iterating over the list in case it only had 1 entry. Simplify VMObject by removing this counter and always iterating the list even if there's only 1 entry. :^)
2021-07-25Kernel: Remove unnecessary weak pointer from Region to owning ProcessAndreas Kling
This was previously used for a single debug logging statement during memory purging. There are no remaining users of this weak pointer, so let's get rid of it.
2021-07-25Kernel: Make purgeable memory a VMObject level concept (again)Andreas Kling
This patch changes the semantics of purgeable memory. - AnonymousVMObject now has a "purgeable" flag. It can only be set when constructing the object. (Previously, all anonymous memory was effectively purgeable.) - AnonymousVMObject now has a "volatile" flag. It covers the entire range of physical pages. (Previously, we tracked ranges of volatile pages, effectively making it a page-level concept.) - Non-volatile objects maintain a physical page reservation via the committed pages mechanism, to ensure full coverage for page faults. - When an object is made volatile, it relinquishes any unused committed pages immediately. If later made non-volatile again, we then attempt to make a new committed pages reservation. If this fails, we return ENOMEM to userspace. mmap() now creates purgeable objects if passed the MAP_PURGEABLE option together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
2021-07-23Kernel: No need to use safe_memcpy() when handling an inode faultAndreas Kling
We're copying the inode contents from a stack buffer into a page that we just quick-mapped, so there's no reason for this memcpy() to fail.
2021-07-23Kernel: Simplify VMObject locking & page fault handlersAndreas Kling
This patch greatly simplifies VMObject locking by doing two things: 1. Giving VMObject an IntrusiveList of all its mapping Region objects. 2. Removing VMObject::m_paging_lock in favor of VMObject::m_lock Before (1), VMObject::for_each_region() was forced to acquire the global MM lock (since it worked by walking MemoryManager's list of all regions and checking for regions that pointed to itself.) With each VMObject having its own list of Regions, VMObject's own m_lock is all we need. Before (2), page fault handlers used a separate mutex for preventing overlapping work. This design required multiple temporary unlocks and was generally extremely hard to reason about. Instead, page fault handlers now use VMObject's own m_lock as well.
2021-07-23Kernel: Remove unused MAP_SHARED_ZERO_PAGE_LAZILY code pathAndreas Kling
2021-07-22Kernel: Convert Region to east-const styleAndreas Kling
2021-07-22Kernel: Make committed physical page allocation return NonnullRefPtrAndreas Kling
Since we're taking from the committed set of pages, there should never be a reason for this call to fail. Also add a Badge to disallow taking committed pages from anywhere but the Region class.
2021-07-18Kernel: Rename Locker => MutexLockerAndreas Kling
2021-07-12Kernel: Allow Lock to block from BlockConditionTom
This enables the Lock class to block a thread even while the thread is working on a BlockCondition. A thread can still only be either blocked by a Lock or a BlockCondition. This also establishes a linked list of threads that are blocked by a Lock and unblocking directly unlocks threads and wakes them directly.
2021-07-11Kernel: Rename VMObject::clone() => try_clone()Andreas Kling
And fix an unsafe dereference in SharedInodeVMObject::try_clone() to make it OOM-safe.
2021-07-11Kernel: Rename Region::create_kernel_only() => try_create_kernel_only()Andreas Kling
2021-07-11Kernel: Make Region::try_create_user_accessible() OOM-safeAndreas Kling
Previously we would simply assume that Region allocation always succeeded. There is still one such assumption when splitting user regions inside a Space. That will be dealt with in a separate commit.
2021-06-24Everywhere: Use nothrow new with `adopt_{ref,own}_if_nonnull`Daniel Bertalan
This commit converts naked `new`s to `AK::try_make` and `AK::try_create` wherever possible. If the called constructor is private, this can not be done, so we instead now use the standard-defined and compiler-agnostic `new (nothrow)`.
2021-06-16Kernel: Remove various other uses of ssize_tGunnar Beutner
2021-05-29Kernel: Make Region creation API OOM safeBrian Gianforcaro
- Make Region::create_kernel_only OOM safe. - Make Region::create_user_accessible mostly OOM safe, there are still some tendrils to untangle before it and be completely fixed.
2021-05-28Kernel: Use KString for Region namesAndreas Kling
Replace the AK::String used for Region::m_name with a KString. This seems beneficial across the board, but as a specific data point, it reduces time spent in sys$set_mmap_name() by ~50% on test-js. :^)
2021-05-25Kernel: Release the paging lock while reading from the diskTom
Because reading from the disk may preempt, we need to release the paging lock.
2021-05-02Kernel: Change Inode::{read/write}_bytes interface to KResultOr<ssize_t>Brian Gianforcaro
The error handling in all these cases was still using the old style negative values to indicate errors. We have a nicer solution for this now with KResultOr<T>. This change switches the interface and then all implementers to use the new style.
2021-05-01Everywhere: Turn #if *_DEBUG into dbgln_if/if constexprGunnar Beutner
2021-04-25Kernel: Remove the now defunct `LOCKER(..)` macro.Brian Gianforcaro
2021-04-22Everything: Move to SPDX license identifiers in all files.Brian Gianforcaro
SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
2021-03-09Kernel: Convert klog() to dmesgln() in RegionAndreas Kling
2021-03-08Kernel: Make MemoryManager API type-safe for Region::Access enumBrian Gianforcaro
Increase type-safety moving the MemoryManager APIs which take a Region::Access to actually use that type instead of a `u8`. Eventually the actually m_access can be moved there as well, but I hit some weird bug where it wasn't using the correct operators in `set_access_bit(..)` even though it's declared (and tested). Something to fix-up later.
2021-03-03Kernel: Skip TLB flushes while cloning regions in sys$fork()Andreas Kling
Since we know for sure that the virtual memory regions in the new process being created are not being used on any CPU, there's no need to do TLB flushes for every mapped page.
2021-02-23Everywhere: Rename ASSERT => VERIFYAndreas Kling
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED) Since all of these checks are done in release builds as well, let's rename them to VERIFY to prevent confusion, as everyone is used to assertions being compiled out in release. We can introduce a new ASSERT macro that is specifically for debug checks, but I'm doing this wholesale conversion first since we've accumulated thousands of these already, and it's not immediately obvious which ones are suitable for ASSERT.
2021-02-14Kernel: Assert if rounding-up-to-page-size would wrap around to 0Andreas Kling
If we try to align a number above 0xfffff000 to the next multiple of the page size (4 KiB), it would wrap around to 0. This is most likely never what we want, so let's assert if that happens.
2021-02-14Kernel: Panic on attempt to map mmap'ed page at a kernel addressAndreas Kling
If we somehow get tricked into mapping user-controlled mmap memory at a kernel address, let's just panic the kernel.
2021-02-14Kernel: Make the Region constructor privateAndreas Kling
We can use adopt_own(*new T) instead of make<T>().
2021-02-14Kernel: Remove user/kernel flags from RegionAndreas Kling
Now that we no longer need to support the signal trampolines being user-accessible inside the kernel memory range, we can get rid of the "kernel" and "user-accessible" flags on Region and simply use the address of the region to determine whether it's kernel or user. This also tightens the page table mapping code, since it can now set user-accessibility based solely on the virtual address of a page.
2021-02-13Kernel: Sanity check the VM range when constructing a RegionAndreas Kling
This should help us catch bogus VM ranges ending up in a process's address space sooner.
2021-02-08Everywhere: Replace dbgln<flag>(...) with dbgln_if(flag, ...)AnotherTest
Replacement made by `find Kernel Userland -name '*.h' -o -name '*.cpp' | sed -i -Ee 's/dbgln\b<(\w+)>\(/dbgln_if(\1, /g'`
2021-02-02Kernel: Add a way to specify which memory regions can make syscallsAndreas Kling
This patch adds sys$msyscall() which is loosely based on an OpenBSD mechanism for preventing syscalls from non-blessed memory regions. It works similarly to pledge and unveil, you can call it as many times as you like, and when you're finished, you call it with a null pointer and it will stop accepting new regions from then on. If a syscall later happens and doesn't originate from one of the previously blessed regions, the kernel will simply crash the process.
2021-01-29Kernel: Enforce W^X more strictly (like PaX MPROTECT)Andreas Kling
This patch adds enforcement of two new rules: - Memory that was previously writable cannot become executable - Memory that was previously executable cannot become writable Unfortunately we have to make an exception for text relocations in the dynamic loader. Since those necessitate writing into a private copy of library code, we allow programs to transition from RW to RX under very specific conditions. See the implementation of sys$mprotect()'s should_make_executable_exception_for_dynamic_loader() for details.
2021-01-27Kernel: Release MM lock while yielding from inode page fault handlerTom
We need to make sure other processors can grab the MM lock while we wait, so release it when we might block. Reading the page from disk may also block, so release it during that time as well.
2021-01-26Meta: Split debug defines into multiple headers.asynts
The following script was used to make these changes: #!/bin/bash set -e tmp=$(mktemp -d) echo "tmp=$tmp" find Kernel \( -name '*.cpp' -o -name '*.h' \) | sort > $tmp/Kernel.files find . \( -path ./Toolchain -prune -o -path ./Build -prune -o -path ./Kernel -prune \) -o \( -name '*.cpp' -o -name '*.h' \) -print | sort > $tmp/EverythingExceptKernel.files cat $tmp/Kernel.files | xargs grep -Eho '[A-Z0-9_]+_DEBUG' | sort | uniq > $tmp/Kernel.macros cat $tmp/EverythingExceptKernel.files | xargs grep -Eho '[A-Z0-9_]+_DEBUG' | sort | uniq > $tmp/EverythingExceptKernel.macros comm -23 $tmp/Kernel.macros $tmp/EverythingExceptKernel.macros > $tmp/Kernel.unique comm -1 $tmp/Kernel.macros $tmp/EverythingExceptKernel.macros > $tmp/EverythingExceptKernel.unique cat $tmp/Kernel.unique | awk '{ print "#cmakedefine01 "$1 }' > $tmp/Kernel.header cat $tmp/EverythingExceptKernel.unique | awk '{ print "#cmakedefine01 "$1 }' > $tmp/EverythingExceptKernel.header for macro in $(cat $tmp/Kernel.unique) do cat $tmp/Kernel.files | xargs grep -l $macro >> $tmp/Kernel.new-includes ||: done cat $tmp/Kernel.new-includes | sort > $tmp/Kernel.new-includes.sorted for macro in $(cat $tmp/EverythingExceptKernel.unique) do cat $tmp/Kernel.files | xargs grep -l $macro >> $tmp/Kernel.old-includes ||: done cat $tmp/Kernel.old-includes | sort > $tmp/Kernel.old-includes.sorted comm -23 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.new comm -13 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.old comm -12 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.mixed for file in $(cat $tmp/Kernel.includes.new) do sed -i -E 's/#include <AK\/Debug\.h>/#include <Kernel\/Debug\.h>/' $file done for file in $(cat $tmp/Kernel.includes.mixed) do echo "mixed include in $file, requires manual editing." done
2021-01-26Kernel: Assert on attempt to map private region backed by shared inodeAndreas Kling
If we find ourselves with a user-accessible, non-shared Region backed by a SharedInodeVMObject, that's pretty bad news, so let's just panic the kernel instead of getting abused. There might be a better place for this kind of check, so I've added a FIXME about putting more thought into that.
2021-01-26Kernel: sys$munmap() region splitting did not preserve "shared" flagAndreas Kling
This was exploitable since the shared flag determines whether inode permission checks are applied in sys$mprotect(). The bug was pretty hard to spot due to default arguments being used instead. This patch removes the default arguments to make explicit at each call site what's being done.
2021-01-25Everywhere: Debug macros instead of constexpr.asynts
This was done with the following script: find . \( -name '*.cpp' -o -name '*.h' -o -name '*.in' \) -not -path './Toolchain/*' -not -path './Build/*' -exec sed -i -E 's/dbgln<debug_([a-z_]+)>/dbgln<\U\1_DEBUG>/' {} \; find . \( -name '*.cpp' -o -name '*.h' -o -name '*.in' \) -not -path './Toolchain/*' -not -path './Build/*' -exec sed -i -E 's/if constexpr \(debug_([a-z0-9_]+)/if constexpr \(\U\1_DEBUG/' {} \;
2021-01-25Everywhere: Use CMake to generate AK/Debug.h.asynts
This was done with the help of several scripts, I dump them here to easily find them later: awk '/#ifdef/ { print "#cmakedefine01 "$2 }' AK/Debug.h.in for debug_macro in $(awk '/#ifdef/ { print $2 }' AK/Debug.h.in) do find . \( -name '*.cpp' -o -name '*.h' -o -name '*.in' \) -not -path './Toolchain/*' -not -path './Build/*' -exec sed -i -E 's/#ifdef '$debug_macro'/#if '$debug_macro'/' {} \; done # Remember to remove WRAPPER_GERNERATOR_DEBUG from the list. awk '/#cmake/ { print "set("$2" ON)" }' AK/Debug.h.in
2021-01-22Everywhere: Replace a bundle of dbg with dbgln.asynts
These changes are arbitrarily divided into multiple commits to make it easier to find potentially introduced bugs with git bisect.
2021-01-16Kernel: Remove unused syscall sys$minherit()Andreas Kling
This is no longer used. We can bring it back the day we need it.
2021-01-11Kernel: Remove MM_DEBUG debug spam codeAndreas Kling
This was too spammy to ever actually be used anyway.
2021-01-11Kernel: Convert a bunch of String::format() => String::formatted()Andreas Kling
2021-01-11Everywhere: Fix incorrect uses of String::format and StringBuilder::appendfSahan Fernando
These changes are arbitrarily divided into multiple commits to make it easier to find potentially introduced bugs with git bisect.
2021-01-11Everywhere: Replace a bundle of dbg with dbgln.asynts
These changes are arbitrarily divided into multiple commits to make it easier to find potentially introduced bugs with git bisect.Everything:
2021-01-09Everywhere: Replace a bundle of dbg with dbgln.asynts
These changes are arbitrarily divided into multiple commits to make it easier to find potentially introduced bugs with git bisect.Everything: The modifications in this commit were automatically made using the following command: find . -name '*.cpp' -exec sed -i -E 's/dbg\(\) << ("[^"{]*");/dbgln\(\1\);/' {} \;
2021-01-02Kernel: Ignore TLB flush requests for user addresses of other processesTom
If a TLB flush request is broadcast to other processors and the addresses to flush are user mode addresses, we can ignore such a request on the target processor if the page directory currently in use doesn't match the addresses to be flushed. We still need to broadcast to all processors in that case because the other processors may switch to that same page directory at any time.
2021-01-02Kernel: If a VMObject is shared, broadcast page remappingsTom
If we remap pages (e.g. lazy allocation) inside a VMObject that is shared among more than one region, broadcast it to any other region that may be mapping the same page.
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