At boot we print the ranges we've mapped for the linear mapping and
what page size we've used. Also track whether the range is mapped
executable or not and display that as well.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If we look closely at the logic in create_physical_mapping(), when
we're doing STRICT_KERNEL_RWX, we do the following steps:
- determine the gap from where we are to the end of the range
- choose an appropriate mapping_size based on the gap
- check if that mapping_size would overlap the __init_begin
boundary, and if not choose an appropriate mapping_size
We can simplify the logic by taking the __init_begin boundary into
account when we calculate the initial gap.
So add a next_boundary() function which tells us what the next
boundary is, either the __init_begin boundary or end. In future we can
add more boundaries.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When we have CONFIG_STRICT_KERNEL_RWX enabled, we want to split the
linear mapping at the text/data boundary so we can map the kernel
text read only.
The current logic uses a goto inside the for loop, which works, but is
hard to reason about.
When we hit the goto retry case we set max_mapping_size to PMD_SIZE
and go back to the start.
Setting max_mapping_size means we skip the PUD case and go to the PMD
case.
We know we will pass the alignment and gap checks because the only
reason we are there is we hit the goto retry, and that is guarded by
mapping_size == PUD_SIZE, which means addr is PUD aligned and gap is
greater or equal to PUD_SIZE.
So the only part of the check that can fail is the mmu_psize_defs
check for the 2M page size.
If we just duplicate that check we can avoid the goto, and we get the
same result.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When we have CONFIG_STRICT_KERNEL_RWX enabled, we want to split the
linear mapping at the text/data boundary so we can map the kernel
text read only.
Currently we always use a small page at the text/data boundary, even
when that's not necessary:
Mapped 0x0000000000000000-0x0000000000e00000 with 2.00 MiB pages
Mapped 0x0000000000e00000-0x0000000001000000 with 64.0 KiB pages
Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages
This is because the check that the mapping crosses the __init_begin
boundary is too strict, it also returns true when we map exactly up to
the boundary.
So fix it to check that the mapping would actually map past
__init_begin, and with that we see:
Mapped 0x0000000000000000-0x0000000040000000 with 2.00 MiB pages
Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When we have CONFIG_STRICT_KERNEL_RWX enabled, we want to split the
linear mapping at the text/data boundary so we can map the kernel text
read only.
But the current logic uses small pages for the entire text section,
regardless of whether a larger page size would fit. eg. with the
boundary at 16M we could use 2M pages, but instead we use 64K pages up
to the 16M boundary:
Mapped 0x0000000000000000-0x0000000001000000 with 64.0 KiB pages
Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages
Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
This is because the test is checking if addr is < __init_begin
and addr + mapping_size is >= _stext. But that is true for all pages
between _stext and __init_begin.
Instead what we want to check is if we are crossing the text/data
boundary, which is at __init_begin. With that fixed we see:
Mapped 0x0000000000000000-0x0000000000e00000 with 2.00 MiB pages
Mapped 0x0000000000e00000-0x0000000001000000 with 64.0 KiB pages
Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages
Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
ie. we're correctly using 2MB pages below __init_begin, but we still
drop down to 64K pages unnecessarily at the boundary.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When we have CONFIG_STRICT_KERNEL_RWX enabled, we try to split the
kernel linear (1:1) mapping so that the kernel text is in a separate
page to kernel data, so we can mark the former read-only.
We could achieve that just by always using 64K pages for the linear
mapping, but we try to be smarter. Instead we use huge pages when
possible, and only switch to smaller pages when necessary.
However we have an off-by-one bug in that logic, which causes us to
calculate the wrong boundary between text and data.
For example with the end of the kernel text at 16M we see:
radix-mmu: Mapped 0x0000000000000000-0x0000000001200000 with 64.0 KiB pages
radix-mmu: Mapped 0x0000000001200000-0x0000000040000000 with 2.00 MiB pages
radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
ie. we mapped from 0 to 18M with 64K pages, even though the boundary
between text and data is at 16M.
With the fix we see we're correctly hitting the 16M boundary:
radix-mmu: Mapped 0x0000000000000000-0x0000000001000000 with 64.0 KiB pages
radix-mmu: Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages
radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The Nest MMU workaround is only needed for RW upgrades. Avoid doing
that for other PTE updates.
We also avoid clearing the PTE while marking it invalid. This is
because other page table walkers will find this PTE none and can
result in unexpected behaviour due to that. Instead we clear
_PAGE_PRESENT and set the software PTE bit _PAGE_INVALID.
pte_present() is already updated to check for both bits. This makes
sure page table walkers will find the PTE present and things like
pte_pfn(pte) returns the right value.
Based on an original patch from Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add statistics that show how memory is mapped within the kernel linear mapping.
This is similar to commit 37cd944c8d ("s390/pgtable: add mapping statistics")
We don't do this with Hash translation mode. Hash uses one size (mmu_linear_psize)
to map the kernel linear mapping and we print the linear psize during boot as
below.
"Page orders: linear mapping = 24, virtual = 16, io = 16, vmemmap = 24"
A sample output looks like:
DirectMap4k: 0 kB
DirectMap64k: 18432 kB
DirectMap2M: 1030144 kB
DirectMap1G: 11534336 kB
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
POWER9 DD1 was never a product. It is no longer supported by upstream
firmware, and it is not effectively supported in Linux due to lack of
testing.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
[mpe: Remove arch_make_huge_pte() entirely]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The ISA suggests ptesync after setting a pte, to prevent a table walk
initiated by a subsequent access from missing that store and causing a
spurious fault. This is an architectual allowance that allows an
implementation's page table walker to be incoherent with the store
queue.
However there is no correctness problem in taking a spurious fault in
userspace -- the kernel copes with these at any time, so the updated
pte will be found eventually. Spurious kernel faults on vmap memory
must be avoided, so a ptesync is put into flush_cache_vmap.
On POWER9 so far I have not found a measurable window where this can
result in more minor faults, so as an optimisation, remove the costly
ptesync from pte updates. If an implementation benefits from ptesync,
it would be better to add it back in update_mmu_cache, so it's not
done for things like fork(2).
fork --fork --exec benchmark improved 5.2% (12400->13100).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Radix flushes the TLB when updating ptes to increase permissiveness
of protection (increase access authority). Book3S does not require
TLB flushing in this case, and it is not done on hash. This patch
avoids the flush for radix.
>From Power ISA v3.0B, p.1090:
Setting a Reference or Change Bit or Upgrading Access Authority
(PTE Subject to Atomic Hardware Updates)
If the only change being made to a valid PTE that is subject to
atomic hardware updates is to set the Reference or Change bit to 1
or to add access authorities, a simpler sequence suffices because
the translation hardware will refetch the PTE if an access is
attempted for which the only problems were reference and/or change
bits needing to be set or insufficient access authority.
The nest MMU on POWER9 does not re-fetch the PTE after such an access
attempt before faulting, so address spaces with a coprocessor
attached will continue to flush in these cases.
This reduces tlbies for a kernel compile workload from 1.28M to 0.95M,
tlbiels from 20.17M 19.68M.
fork --fork --exec benchmark improved 2.77% (12000->12300).
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When relaxing access (read -> read_write update), pte needs to be marked invalid
to handle a nest MMU bug. We also need to do a tlb flush after the pte is
marked invalid before updating the pte with new access bits.
We also move tlb flush to platform specific __ptep_set_access_flags. This will
help us to gerid of unnecessary tlb flush on BOOK3S 64 later. We don't do that
in this patch. This also helps in avoiding multiple tlbies with coprocessor
attached.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In later patch, we use the vma and psize to do tlb flush. Do the prototype
update in separate patch to make the review easy.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In later patch we will update them which require them to be moved
to pgtable-radix.c. Keeping the function in radix.h results in
compile warning as below.
./arch/powerpc/include/asm/book3s/64/radix.h: In function ‘radix__ptep_set_access_flags’:
./arch/powerpc/include/asm/book3s/64/radix.h:196:28: error: dereferencing pointer to incomplete type ‘struct vm_area_struct’
struct mm_struct *mm = vma->vm_mm;
^~
./arch/powerpc/include/asm/book3s/64/radix.h:204:6: error: implicit declaration of function ‘atomic_read’; did you mean ‘__atomic_load’? [-Werror=implicit-function-declaration]
atomic_read(&mm->context.copros) > 0) {
^~~~~~~~~~~
__atomic_load
./arch/powerpc/include/asm/book3s/64/radix.h:204:21: error: dereferencing pointer to incomplete type ‘struct mm_struct’
atomic_read(&mm->context.copros) > 0) {
Instead of fixing header dependencies, we move the function to pgtable-radix.c
Also the function is now large to be a static inline . Doing the
move in separate patch helps in review.
No functional change in this patch. Only code movement.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In later patch we switch pmd_lock from mm->page_table_lock to split pmd ptlock.
It avoid compilations issues, use pmd_lockptr helper.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With split PTL (page table lock) config, we allocate the level
4 (leaf) page table using pte fragment framework instead of slab cache
like other levels. This was done to enable us to have split page table
lock at the level 4 of the page table. We use page->plt backing the
all the level 4 pte fragment for the lock.
Currently with Radix, we use only 16 fragments out of the allocated
page. In radix each fragment is 256 bytes which means we use only 4k
out of the allocated 64K page wasting 60k of the allocated memory.
This was done earlier to keep it closer to hash.
This patch update the pte fragment count to 256, thereby using the
full 64K page and reducing the memory usage. Performance tests shows
really low impact even with THP disabled. With THP disabled we will be
contenting further less on level 4 ptl and hence the impact should be
further low.
256 threads:
without patch (10 runs of ./ebizzy -m -n 1000 -s 131072 -S 100)
median = 15678.5
stdev = 42.1209
with patch:
median = 15354
stdev = 194.743
This is with THP disabled. With THP enabled the impact of the patch
will be less.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Bring in yet another series that touches KVM code, and might need to
be merged into the kvm-ppc branch to resolve conflicts.
This required some changes in pnv_power9_force_smt4_catch/release()
due to the paca array becomming an array of pointers.
Try to allocate kernel page tables for direct mapping and vmemmap
according to the node of the memory they will map. The node is not
available for the linear map in early boot, so use range allocation
to allocate the page tables from the region they map, which is
effectively node-local.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fix build error in radix__create_section_mapping()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Fix the warning messages for stop_machine_change_mapping(), and a number
of other affected functions in its call chain.
All modified functions are under CONFIG_MEMORY_HOTPLUG, so __meminit
is okay (keeps them / does not discard them).
Boot-tested on powernv/power9/radix-mmu and pseries/power8/hash-mmu.
$ make -j$(nproc) CONFIG_DEBUG_SECTION_MISMATCH=y vmlinux
...
MODPOST vmlinux.o
WARNING: vmlinux.o(.text+0x6b130): Section mismatch in reference from the function stop_machine_change_mapping() to the function .meminit.text:create_physical_mapping()
The function stop_machine_change_mapping() references
the function __meminit create_physical_mapping().
This is often because stop_machine_change_mapping lacks a __meminit
annotation or the annotation of create_physical_mapping is wrong.
WARNING: vmlinux.o(.text+0x6b13c): Section mismatch in reference from the function stop_machine_change_mapping() to the function .meminit.text:create_physical_mapping()
The function stop_machine_change_mapping() references
the function __meminit create_physical_mapping().
This is often because stop_machine_change_mapping lacks a __meminit
annotation or the annotation of create_physical_mapping is wrong.
...
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
To support memory keys, we moved the hash pte slot information to the
second half of the page table. This was ok with PTE entries at level
4 (PTE page) and level 3 (PMD). We already allocate larger page table
pages at those levels to accomodate extra details. For level 4 we
already have the extra space which was used to track 4k hash page
table entry details and at level 3 the extra space was allocated to
track the THP details.
With hugetlbfs PTE, we used this extra space at the PMD level to store
the slot details. But we also support hugetlbfs PTE at PUD level for
16GB pages and PUD level page didn't allocate extra space. This
resulted in memory corruption.
Fix this by allocating extra space at PUD level when HUGETLB is
enabled.
Fixes: bf9a95f9a6 ("powerpc: Free up four 64K PTE bits in 64K backed HPTE pages")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch splits the linear mapping if the hot-unplug range is
smaller than the mapping size. The code detects if the mapping needs
to be split into a smaller size and if so, uses the stop machine
infrastructure to clear the existing mapping and then remap the
remaining range using a smaller page size.
The code will skip any region of the mapping that overlaps with kernel
text and warn about it once. We don't want to remove a mapping where
the kernel text and the LMB we intend to remove overlap in the same
TLB mapping as it may affect the currently executing code.
I've tested these changes under a kvm guest with 2 vcpus, from a split
mapping point of view, some of the caveats mentioned above applied to
the testing I did.
Fixes: 4b5d62ca17 ("powerpc/mm: add radix__remove_section_mapping()")
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Tweak change log to match updated behaviour]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This change restores and formalises the behaviour that access to NULL
or other user addresses by the kernel during boot should fault rather
than succeed and modify memory. This was inadvertently broken when
fixing another bug, because it was previously not well defined and
only worked by chance.
powerpc/64s/radix uses high address bits to select an address space
"quadrant", which determines which PID and LPID are used to translate
the rest of the address (effective PID, effective LPID). The kernel
mapping at 0xC... selects quadrant 3, which uses PID=0 and LPID=0. So
the kernel page tables are installed in the PID 0 process table entry.
An address at 0x0... selects quadrant 0, which uses PID=PIDR for
translating the rest of the address (that is, it uses the value of the
PIDR register as the effective PID). If PIDR=0, then the translation
is performed with the PID 0 process table entry page tables. This is
the kernel mapping, so we effectively get another copy of the kernel
address space at 0. A NULL pointer access will access physical memory
address 0.
To prevent duplicating the kernel address space in quadrant 0, this
patch allocates a guard PID containing no translations, and
initializes PIDR with this during boot, before the MMU is switched on.
Any kernel access to quadrant 0 will use this guard PID for
translation and find no valid mappings, and therefore fault.
After boot, this PID will be switchd away to user context PIDs, but
those contain user mappings (and usually NULL pointer protection)
rather than kernel mapping, which is much safer (and by design). It
may be in future this is tightened further, which the guard PID could
be used for.
Commit 371b8044 ("powerpc/64s: Initialize ISAv3 MMU registers before
setting partition table"), introduced this problem because it zeroes
PIDR at boot. However previously the value was inherited from firmware
or kexec, which is not robust and can be zero (e.g., mambo).
Fixes: 371b80447f ("powerpc/64s: Initialize ISAv3 MMU registers before setting partition table")
Cc: stable@vger.kernel.org # v4.15+
Reported-by: Florian Weimer <fweimer@redhat.com>
Tested-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With the previous patch to switch to 64-bit mode after returning from
RTAS and before doing any memory accesses, the RMA limit need not be
clamped to 1GB to avoid RTAS bugs.
Keep the 1GB limit for older firmware (although this is more of a kernel
concern than RTAS), and remove it starting with POWER9.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The radix guest is not subject to the paravirtualized HPT VRMA limit,
so remove that from ppc64_rma_size calculation for that platform.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This removes the RMA limit on powernv platform, which constrains
early allocations such as PACAs and stacks. There are still other
restrictions that must be followed, such as bolted SLB limits, but
real mode addressing has no constraints.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are several cases outside the normal address space management
where a CPU's entire local TLB is to be flushed:
1. Booting the kernel, in case something has left stale entries in
the TLB (e.g., kexec).
2. Machine check, to clean corrupted TLB entries.
One other place where the TLB is flushed, is waking from deep idle
states. The flush is a side-effect of calling ->cpu_restore with the
intention of re-setting various SPRs. The flush itself is unnecessary
because in the first case, the TLB should not acquire new corrupted
TLB entries as part of sleep/wake (though they may be lost).
This type of TLB flush is coded inflexibly, several times for each CPU
type, and they have a number of problems with ISA v3.0B:
- The current radix mode of the MMU is not taken into account, it is
always done as a hash flushn For IS=2 (LPID-matching flush from host)
and IS=3 with HV=0 (guest kernel flush), tlbie(l) is undefined if
the R field does not match the current radix mode.
- ISA v3.0B hash must flush the partition and process table caches as
well.
- ISA v3.0B radix must flush partition and process scoped translations,
partition and process table caches, and also the page walk cache.
So consolidate the flushing code and implement it in C and inline asm
under the mm/ directory with the rest of the flush code. Add ISA v3.0B
cases for radix and hash, and use the radix flush in radix environment.
Provide a way for IS=2 (LPID flush) to specify the radix mode of the
partition. Have KVM pass in the radix mode of the guest.
Take out the flushes from early cputable/dt_cpu_ftrs detection hooks,
and move it later in the boot process after, the MMU registers are set
up and before relocation is first turned on.
The TLB flush is no longer called when restoring from deep idle states.
This was not be done as a separate step because booting secondaries
uses the same cpu_restore as idle restore, which needs the TLB flush.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When using the radix MMU on Power9 DD1, to work around a hardware
problem, radix__pte_update() is required to do a two stage update of
the PTE. First we write a zero value into the PTE, then we flush the
TLB, and then we write the new PTE value.
In the normal case that works OK, but it does not work if we're
updating the PTE that maps the code we're executing, because the
mapping is removed by the TLB flush and we can no longer execute from
it. Unfortunately the STRICT_RWX code needs to do exactly that.
The exact symptoms when we hit this case vary, sometimes we print an
oops and then get stuck after that, but I've also seen a machine just
get stuck continually page faulting with no oops printed. The variance
is presumably due to the exact layout of the text and the page size
used for the mappings. In all cases we are unable to boot to a shell.
There are possible solutions such as creating a second mapping of the
TLB flush code, executing from that, and then jumping back to the
original. However we don't want to add that level of complexity for a
DD1 work around.
So just detect that we're running on Power9 DD1 and refrain from
changing the permissions, effectively disabling STRICT_RWX on Power9
DD1.
Fixes: 7614ff3272 ("powerpc/mm/radix: Implement STRICT_RWX/mark_rodata_ro() for Radix")
Cc: stable@vger.kernel.org # v4.13+
Reported-by: Andrew Jeffery <andrew@aj.id.au>
[Changelog as suggested by Michael Ellerman <mpe@ellerman.id.au>]
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When we map memory at boot we print out the ranges of real addresses
that we mapped and the page size that was used.
Currently it's a bit ugly:
Mapped range 0x0 - 0x2000000000 with 0x40000000
Mapped range 0x200000000000 - 0x202000000000 with 0x40000000
Pad the addresses so they line up, and print the page size using
actual units, eg:
Mapped 0x0000000000000000-0x0000000001200000 with 64.0 KiB pages
Mapped 0x0000000001200000-0x0000000040000000 with 2.00 MiB pages
Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There's a non-trivial dependency between some commits we want to put in
next and the KVM prefetch work around that went into fixes. So merge
fixes into next.
Now that we made sure that lockless walk of linux page table is mostly
limitted to current task(current->mm->pgdir) we can update the THP
update sequence to only send IPI to CPUs on which this task has run.
This helps in reducing the IPI overload on systems with large number
of CPUs.
WRT kvm even though kvm is walking page table with vpc->arch.pgdir,
it is done only on secondary CPUs and in that case we have primary CPU
added to task's mm cpumask. Sending an IPI to primary will force the
secondary to do a vm exit and hence this mm cpumask usage is safe
here.
WRT CAPI, we still end up walking linux page table with capi context
MM. For now the pte lookup serialization sends an IPI to all CPUs in
CPI is in use. We can further improve this by adding the CAPI
interrupt handling CPU to task mm cpumask. That will be done in a
later patch.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The host process table base is stored in the partition table by calling
the function native_register_process_table(). Currently this just sets
the entry in memory and is missing a subsequent cache invalidation
instruction. Any update to the partition table should be followed by a
cache invalidation instruction specifying invalidation of the caching of
any partition table entries (RIC = 2, PRS = 0).
We already have a function to update the partition table with the
required cache invalidation instructions - mmu_partition_table_set_entry().
Update the native_register_process_table() function to call
mmu_partition_table_set_entry(), this ensures all appropriate
invalidation will be performed.
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Use a local for patb0 to clean it up slightly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently KERN_IO_START is defined as:
#define KERN_IO_START (KERN_VIRT_START + (KERN_VIRT_SIZE >> 1))
Although it looks like a constant, both the components are actually
variables, to allow us to have a different value between Radix and
Hash with a single kernel.
However that still requires both Radix and Hash to place the kernel IO
region at the same location relative to the start and end of the
kernel virtual region (namely 1/2 way through it), and we'd like to
change that.
So split KERN_IO_START out into its own variable, and initialise it
for Radix and Hash. In the medium term we should be able to
reconsolidate this, by doing a more involved rearrangement of the
location of the regions.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We do that because it's used by THP pmd collapsing, so use
instead a dedicated flush function.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There's a somewhat architectural issue with Radix MMU and KVM.
When coming out of a guest with AIL (Alternate Interrupt Location, ie,
MMU enabled), we start executing hypervisor code with the PID register
still containing whatever the guest has been using.
The problem is that the CPU can (and will) then start prefetching or
speculatively load from whatever host context has that same PID (if
any), thus bringing translations for that context into the TLB, which
Linux doesn't know about.
This can cause stale translations and subsequent crashes.
Fixing this in a way that is neither racy nor a huge performance
impact is difficult. We could just make the host invalidations always
use broadcast forms but that would hurt single threaded programs for
example.
We chose to fix it instead by partitioning the PID space between guest
and host. This is possible because today Linux only use 19 out of the
20 bits of PID space, so existing guests will work if we make the host
use the top half of the 20 bits space.
We additionally add support for a property to indicate to Linux the
size of the PID register which will be useful if we eventually have
processors with a larger PID space available.
There is still an issue with malicious guests purposefully setting the
PID register to a value in the hosts PID range. Hopefully future HW
can prevent that, but in the meantime, we handle it with a pair of
kludges:
- On the way out of a guest, before we clear the current VCPU in the
PACA, we check the PID and if it's outside of the permitted range
we flush the TLB for that PID.
- When context switching, if the mm is "new" on that CPU (the
corresponding bit was set for the first time in the mm cpumask), we
check if any sibling thread is in KVM (has a non-NULL VCPU pointer
in the PACA). If that is the case, we also flush the PID for that
CPU (core).
This second part is needed to handle the case where a process is
migrated (or starts a new pthread) on a sibling thread of the CPU
coming out of KVM, as there's a window where stale translations can
exist before we detect it and flush them out.
A future optimization could be added by keeping track of whether the
PID has ever been used and avoid doing that for completely fresh PIDs.
We could similarily mark PIDs that have been the subject of a global
invalidation as "fresh". But for now this will do.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Rework the asm to build with CONFIG_PPC_RADIX_MMU=n, drop
unneeded include of kvm_book3s_asm.h]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently even with STRICT_KERNEL_RWX we leave the __init text marked
executable after init, which is bad.
Add a hook to mark it NX (no-execute) before we free it, and implement
it for radix and hash.
Note that we use __init_end as the end address, not _einittext,
because overlaps_kernel_text() uses __init_end, because there are
additional executable sections other than .init.text between
__init_begin and __init_end.
Tested on radix and hash with:
0:mon> p $__init_begin
*** 400 exception occurred
Fixes: 1e0fc9d1eb ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the core logic into a helper, so we can use it for changing permissions
other than _PAGE_WRITE.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The Radix linear mapping code (create_physical_mapping()) tries to use
the largest page size it can at each step. Currently the only reason
it steps down to a smaller page size is if the start addr is
unaligned (never happens in practice), or the end of memory is not
aligned to a huge page boundary.
To support STRICT_RWX we need to break the mapping at __init_begin,
so that the text and rodata prior to that can be marked R_X and the
regular pages after can be marked RW.
Having done that we can now implement mark_rodata_ro() for Radix,
knowing that we won't need to split any mappings.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Split down to PAGE_SIZE, not 2MB, rewrite change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Commit 9abcc981de ("powerpc/mm/radix: Only add X for pages
overlapping kernel text") changed the linear mapping on Radix to only
mark the kernel text executable.
However if the kernel is run relocated, for example as a kdump kernel,
then the exception vectors are split from the kernel text, ie. they
remain at real address 0.
We tend to get away with it, because the kernel itself will usually be
below 1G, which means the 1G page at 0-1G is marked executable and
everything works OK. However if the kernel is loaded above 1G, or the
system has less than 1G in total (meaning we can't use a 1G page),
then the exception vectors will not be marked executable and the
kernel will fail to boot.
Fix it by also checking if the address range overlaps the exception
vectors when deciding if we should add PAGE_KERNEL_X.
Fixes: 9abcc981de ("powerpc/mm/radix: Only add X for pages overlapping kernel text")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Combine with the existing check, rewrite change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add support for the devmap bit on PTEs and PMDs for PPC64 Book3S. This
is used to differentiate device backed memory from transparent huge
pages since they are handled in more or less the same manner by the core
mm code.
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add a trace point for tlbie(l) (Translation Lookaside Buffer Invalidate
Entry (Local)) instructions.
The tlbie instruction has changed over the years, so not all versions
accept the same operands. Use the ISA v3 field operands because they are
the most verbose, we may change them in future.
Example output:
qemu-system-ppc-5371 [016] 1412.369519: tlbie:
tlbie with lpid 0, local 1, rb=67bd8900174c11c1, rs=0, ric=0 prs=0 r=0
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Add some missing trace_tlbie()s, reword change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently we map the whole linear mapping with PAGE_KERNEL_X. Instead we
should check if the page overlaps the kernel text and only then add
PAGE_KERNEL_X.
Note that we still use 1G pages if they're available, so this will
typically still result in a 1G executable page at KERNELBASE. So this fix is
primarily useful for catching stray branches to high linear mapping addresses.
Without this patch, we can execute at 1G in xmon using:
0:mon> m c000000040000000
c000000040000000 00 l
c000000040000000 00000000 01006038
c000000040000004 00000000 2000804e
c000000040000008 00000000 x
0:mon> di c000000040000000
c000000040000000 38600001 li r3,1
c000000040000004 4e800020 blr
0:mon> p c000000040000000
return value is 0x1
After we get a 400 as expected:
0:mon> p c000000040000000
*** 400 exception occurred
Fixes: 2bfd65e45e ("powerpc/mm/radix: Add radix callbacks for early init routines")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Five fairly small fixes for things that went in this cycle.
A fairly large patch to rework the CAS logic on Power9, necessitated by a late
change to the firmware API, and we can't boot without it.
Three fixes going to stable, allowing more instructions to be emulated on LE,
fixing a boot crash on 32-bit Freescale BookE machines, and the OPAL XICS
workaround.
And a patch from me to sort the selects under CONFIG PPC. Annoying churn, but
worth it in the long run, and best for it to go in now to avoid conflicts.
Thanks to:
Alexey Kardashevskiy, Anton Blanchard, Balbir Singh, Gautham R. Shenoy,
Laurentiu Tudor, Nicholas Piggin, Paul Mackerras, Ravi Bangoria, Sachin Sant,
Shile Zhang, Suraj Jitindar Singh.
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Merge tag 'powerpc-4.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
"Five fairly small fixes for things that went in this cycle.
A fairly large patch to rework the CAS logic on Power9, necessitated
by a late change to the firmware API, and we can't boot without it.
Three fixes going to stable, allowing more instructions to be emulated
on LE, fixing a boot crash on 32-bit Freescale BookE machines, and the
OPAL XICS workaround.
And a patch from me to sort the selects under CONFIG PPC. Annoying
churn, but worth it in the long run, and best for it to go in now to
avoid conflicts.
Thanks to:
Alexey Kardashevskiy, Anton Blanchard, Balbir Singh, Gautham R.
Shenoy, Laurentiu Tudor, Nicholas Piggin, Paul Mackerras, Ravi
Bangoria, Sachin Sant, Shile Zhang, Suraj Jitindar Singh"
* tag 'powerpc-4.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc: Sort the selects under CONFIG_PPC
powerpc/64: Fix L1D cache shape vector reporting L1I values
powerpc/64: Avoid panic during boot due to divide by zero in init_cache_info()
powerpc: Update to new option-vector-5 format for CAS
powerpc: Parse the command line before calling CAS
powerpc/xics: Work around limitations of OPAL XICS priority handling
powerpc/64: Fix checksum folding in csum_add()
powerpc/powernv: Fix opal tracepoints with JUMP_LABEL=n
powerpc/booke: Fix boot crash due to null hugepd
powerpc: Fix compiling a BE kernel with a powerpc64le toolchain
selftest/powerpc: Fix false failures for skipped tests
powerpc/powernv: Fix bug due to labeling ambiguity in power_enter_stop
powerpc/64: Invalidate process table caching after setting process table
powerpc: emulate_step() tests for load/store instructions
powerpc: Emulation support for load/store instructions on LE
The POWER9 MMU reads and caches entries from the process table.
When we kexec from one kernel to another, the second kernel sets
its process table pointer but doesn't currently do anything to
make the CPU invalidate any cached entries from the old process table.
This adds a tlbie (TLB invalidate entry) instruction with parameters
to invalidate caching of the process table after the new process
table is installed.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Update code that relied on sched.h including various MM types for them.
This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Highlights include:
- Support for direct mapped LPC on POWER9, giving Linux direct access to
devices that may be on there such as a UART.
- Memory hotplug support for the Power9 Radix MMU.
- Add new AUX vectors describing the processor's cache geometry, to be used by
glibc.
- The ability for a guest to ask the hypervisor to resize the guest's hash
table, and in addition support for doing so automatically when memory is
hotplugged into/out-of the guest. This allows the hash table to be sized
based on the current memory usage of the guest, rather than the maximum
possible memory usage.
- Implementation of optprobes (kprobe optimisation) for powerpc.
In addition there's the topic branch shared with the KVM tree, which includes
support for guests to use the Radix MMU on Power9.
Thanks to:
Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T, Anton Blanchard,
Benjamin Herrenschmidt, Chris Packham, Daniel Axtens, Daniel Borkmann, David
Gibson, Finn Thain, Gautham R. Shenoy, Gavin Shan, Greg Kurz, Joel Stanley,
John Allen, Madhavan Srinivasan, Mahesh Salgaonkar, Markus Elfring, Michael
Neuling, Nathan Fontenot, Naveen N. Rao, Nicholas Piggin, Paul Mackerras, Ravi
Bangoria, Reza Arbab, Shailendra Singh, Vaibhav Jain, Wei Yongjun.
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Merge tag 'powerpc-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Highlights include:
- Support for direct mapped LPC on POWER9, giving Linux direct access
to devices that may be on there such as a UART.
- Memory hotplug support for the Power9 Radix MMU.
- Add new AUX vectors describing the processor's cache geometry, to
be used by glibc.
- The ability for a guest to ask the hypervisor to resize the guest's
hash table, and in addition support for doing so automatically when
memory is hotplugged into/out-of the guest. This allows the hash
table to be sized based on the current memory usage of the guest,
rather than the maximum possible memory usage.
- Implementation of optprobes (kprobe optimisation) for powerpc.
In addition there's the topic branch shared with the KVM tree, which
includes support for guests to use the Radix MMU on Power9.
Thanks to:
Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T, Anton
Blanchard, Benjamin Herrenschmidt, Chris Packham, Daniel Axtens,
Daniel Borkmann, David Gibson, Finn Thain, Gautham R. Shenoy, Gavin
Shan, Greg Kurz, Joel Stanley, John Allen, Madhavan Srinivasan,
Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Nathan Fontenot,
Naveen N. Rao, Nicholas Piggin, Paul Mackerras, Ravi Bangoria, Reza
Arbab, Shailendra Singh, Vaibhav Jain, Wei Yongjun"
* tag 'powerpc-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (129 commits)
powerpc/mm/radix: Skip ptesync in pte update helpers
powerpc/mm/radix: Use ptep_get_and_clear_full when clearing pte for full mm
powerpc/mm/radix: Update pte update sequence for pte clear case
powerpc/mm: Update PROTFAULT handling in the page fault path
powerpc/xmon: Fix data-breakpoint
powerpc/mm: Fix build break with BOOK3S_64=n and MEMORY_HOTPLUG=y
powerpc/mm: Fix build break when CMA=n && SPAPR_TCE_IOMMU=y
powerpc/mm: Fix build break with RADIX=y & HUGETLBFS=n
powerpc/pseries: Fix typo in parameter description
powerpc/kprobes: Remove kprobe_exceptions_notify()
kprobes: Introduce weak variant of kprobe_exceptions_notify()
powerpc/ftrace: Fix confusing help text for DISABLE_MPROFILE_KERNEL
powerpc/powernv: Fix opal_exit tracepoint opcode
powerpc: Add a prototype for mcount() so it can be versioned
powerpc: Drop GPL from of_node_to_nid() export to match other arches
powerpc/kprobes: Optimize kprobe in kretprobe_trampoline()
powerpc/kprobes: Implement Optprobes
powerpc/kprobes: Fixes for kprobe_lookup_name() on BE
powerpc: Add helper to check if offset is within relative branch range
powerpc/bpf: Introduce __PPC_SH64()
...
