In many cases, page tables can be accessed concurrently by either another
CPU (due to things like fast gup) or by the hardware page table walker
itself, which may set access/dirty bits. In such cases, it is important
to use READ_ONCE/WRITE_ONCE when accessing page table entries so that
entries cannot be torn, merged or subject to apparent loss of coherence
due to compiler transformations.
Whilst there are some scenarios where this cannot happen (e.g. pinned
kernel mappings for the linear region), the overhead of using READ_ONCE
/WRITE_ONCE everywhere is minimal and makes the code an awful lot easier
to reason about. This patch consistently uses these macros in the arch
code, as well as explicitly namespacing pointers to page table entries
from the entries themselves by using adopting a 'p' suffix for the former
(as is sometimes used elsewhere in the kernel source).
Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Tested-by: Richard Ruigrok <rruigrok@codeaurora.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In ptdump_check_wx(), we pass walk_pgd() a start address of 0 (rather
than VA_START) for the init_mm. This means that any reported W&X
addresses are offset by VA_START, which is clearly wrong and can make
them appear like userspace addresses.
Fix this by telling the ptdump code that we're walking init_mm starting
at VA_START. We don't need to update the addr_markers, since these are
still valid bounds regardless.
Cc: <stable@vger.kernel.org>
Fixes: 1404d6f13e ("arm64: dump: Add checking for writable and exectuable pages")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <labbott@redhat.com>
Reported-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Page mappings with full RWX permissions are a security risk. x86
has an option to walk the page tables and dump any bad pages.
(See e1a58320a3 ("x86/mm: Warn on W^X mappings")). Add a similar
implementation for arm64.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[catalin.marinas@arm.com: folded fix for KASan out of bounds from Mark Rutland]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The page table dumping code always assumes it will be dumping to a
seq_file to userspace. Future code will be taking advantage of
the page table dumping code but will not need the seq_file. Make
the seq_file optional for these cases.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
ptdump_register currently initializes a set of page table information and
registers debugfs. There are uses for the ptdump option without wanting the
debugfs options. Split this out to make it a separate option.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
When building with 48-bit VAs and 16K page configuration, it's possible
to get the following warning when building the arm64 page table dumping
code:
arch/arm64/mm/dump.c: In function ‘walk_pud’:
arch/arm64/mm/dump.c:274:102: warning: right shift count >= width of type [-Wshift-count-overflow]
This is because pud_offset(pgd, 0) performs a shift to the right by 36
while the value 0 has the type 'int' by default, therefore 32-bit.
This patch modifies all the p*_offset() uses in arch/arm64/mm/dump.c to
use 0UL for the address argument.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
For debugging purposes, it would be nice if we could export page tables
other than the swapper_pg_dir to userspace. To enable this, this patch
refactors the arm64 page table dumping code such that multiple tables
may be registered with the framework, and exported under debugfs.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The page table dump code logs spans of entries at the same level
(pgd/pud/pmd/pte) which have the same attributes. While we log the
(decoded) attributes, we don't log the level, which leaves the output
ambiguous and/or confusing in some cases.
For example:
0xffff800800000000-0xffff800980000000 6G RW NX SHD AF BLK UXN MEM/NORMAL
If using 4K pages, this may describe a span of 6 1G block entries at the
PGD/PUD level, or 3072 2M block entries at the PMD level.
This patch adds the page table level to each output line, removing this
ambiguity. For the example above, this will produce:
0xffffffc800000000-0xffffffc980000000 6G PUD RW NX SHD AF BLK UXN MEM/NORMAL
When 3 level tables are in use, and we use the asm-generic/nopud.h
definitions, the dump code treats each entry in the PGD as a 1 element
table at the PUD level, and logs spans as being PUDs, which can be
confusing. To counteract this, the "PUD" mnemonic is replaced with "PGD"
when CONFIG_PGTABLE_LEVELS <= 3. Likewise for "PMD" when
CONFIG_PGTABLE_LEVELS <= 2.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Huang Shijie <shijie.huang@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Annotate the KASAN shadow region with boundary markers, so that its
mappings stand out in the page table dumper output.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
There is no need to initialize the vmemmap region boundaries dynamically,
since they are compile time constants. So just add these constants to the
global struct initializer, and drop the dynamic assignment and related code.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This moves the vmemmap region right below PAGE_OFFSET, aka the start
of the linear region, and redefines its size to be a power of two.
Due to the placement of PAGE_OFFSET in the middle of the address space,
whose size is a power of two as well, this guarantees that virt to
page conversions and vice versa can be implemented efficiently, by
masking and shifting rather than ordinary arithmetic.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Use VA_START macro in asm/memory.h instead of private LOWEST_ADDR
definition in dump.c.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This moves the module area to right before the vmalloc area, and moves
the kernel image to the base of the vmalloc area. This is an intermediate
step towards implementing KASLR, which allows the kernel image to be
located anywhere in the vmalloc area.
Since other subsystems such as hibernate may still need to refer to the
kernel text or data segments via their linears addresses, both are mapped
in the linear region as well. The linear alias of the text region is
mapped read-only/non-executable to prevent inadvertent modification or
execution.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
With CONFIG_DEBUG_PAGEALLOC, pages do not have the valid bit
set when free in the buddy allocator. Add an indiciation to
the page table dumping code that the valid bit is not set,
'F' for fault, to make this easier to understand.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This patch fixes a typo in mm/dump.c:
"MODUELS_END_NR" should be "MODULES_END_NR".
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The kernel page dump utility needs to be aware of the CONT bit before
it will break up pages ranges for display.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This fix the below build error:
arch/arm64/mm/dump.c: In function ‘ptdump_init’:
arch/arm64/mm/dump.c:331:18: error: ‘VMEMMAP_START_NR’ undeclared (first use in this function)
address_markers[VMEMMAP_START_NR].start_address =
^
arch/arm64/mm/dump.c:331:18: note: each undeclared identifier is reported only once for each
function it appears in
arch/arm64/mm/dump.c:333:18: error: ‘VMEMMAP_END_NR’ undeclared (first use in this function)
address_markers[VMEMMAP_END_NR].start_address =
^
Acked-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Jungseung Lee <js07.lee@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
- reimplementation of the virtual remapping of UEFI Runtime Services in
a way that is stable across kexec
- emulation of the "setend" instruction for 32-bit tasks (user
endianness switching trapped in the kernel, SCTLR_EL1.E0E bit set
accordingly)
- compat_sys_call_table implemented in C (from asm) and made it a
constant array together with sys_call_table
- export CPU cache information via /sys (like other architectures)
- DMA API implementation clean-up in preparation for IOMMU support
- macros clean-up for KVM
- dropped some unnecessary cache+tlb maintenance
- CONFIG_ARM64_CPU_SUSPEND clean-up
- defconfig update (CPU_IDLE)
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
"arm64 updates for 3.20:
- reimplementation of the virtual remapping of UEFI Runtime Services
in a way that is stable across kexec
- emulation of the "setend" instruction for 32-bit tasks (user
endianness switching trapped in the kernel, SCTLR_EL1.E0E bit set
accordingly)
- compat_sys_call_table implemented in C (from asm) and made it a
constant array together with sys_call_table
- export CPU cache information via /sys (like other architectures)
- DMA API implementation clean-up in preparation for IOMMU support
- macros clean-up for KVM
- dropped some unnecessary cache+tlb maintenance
- CONFIG_ARM64_CPU_SUSPEND clean-up
- defconfig update (CPU_IDLE)
The EFI changes going via the arm64 tree have been acked by Matt
Fleming. There is also a patch adding sys_*stat64 prototypes to
include/linux/syscalls.h, acked by Andrew Morton"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (47 commits)
arm64: compat: Remove incorrect comment in compat_siginfo
arm64: Fix section mismatch on alloc_init_p[mu]d()
arm64: Avoid breakage caused by .altmacro in fpsimd save/restore macros
arm64: mm: use *_sect to check for section maps
arm64: drop unnecessary cache+tlb maintenance
arm64:mm: free the useless initial page table
arm64: Enable CPU_IDLE in defconfig
arm64: kernel: remove ARM64_CPU_SUSPEND config option
arm64: make sys_call_table const
arm64: Remove asm/syscalls.h
arm64: Implement the compat_sys_call_table in C
syscalls: Declare sys_*stat64 prototypes if __ARCH_WANT_(COMPAT_)STAT64
compat: Declare compat_sys_sigpending and compat_sys_sigprocmask prototypes
arm64: uapi: expose our struct ucontext to the uapi headers
smp, ARM64: Kill SMP single function call interrupt
arm64: Emulate SETEND for AArch32 tasks
arm64: Consolidate hotplug notifier for instruction emulation
arm64: Track system support for mixed endian EL0
arm64: implement generic IOMMU configuration
arm64: Combine coherent and non-coherent swiotlb dma_ops
...
The {pgd,pud,pmd}_bad family of macros have slightly fuzzy
cross-architecture semantics, and seem to imply a populated entry that
is not a next-level table, rather than a particular type of entry (e.g.
a section map).
In arm64 code, for those cases where we care about whether an entry is a
section mapping, we can instead use the {pud,pmd}_sect macros to
explicitly check for this case. This helps to document precisely what we
care about, making the code easier to read, and allows for future
relaxation of the *_bad macros to check for other "bad" entries.
To that end this patch updates the table dumping and initial table setup
to check for section mappings with {pud,pmd}_sect, and adds/restores
BUG_ON(*_bad((*p)) checks after we've handled the *_sect and *_none
cases so as to catch remaining "bad" cases.
In the fault handling code, show_pte is left with *_bad checks as it
only cares about whether it can walk the next level table, and this path
is used for both kernel and userspace fault handling. The former case
will be followed by a die() where we'll report the address that
triggered the fault, which can be useful context for debugging.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Steve Capper <steve.capper@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The arm64 dump code is currently relying on some definitions which are
pulled in via transitive dependencies. It seems we have implicit
dependencies on the following definitions:
* MODULES_VADDR (asm/memory.h)
* MODULES_END (asm/memory.h)
* PAGE_OFFSET (asm/memory.h)
* PTE_* (asm/pgtable-hwdef.h)
* ENOMEM (linux/errno.h)
* device_initcall (linux/init.h)
This patch ensures we explicitly include the relevant headers for the
above items, fixing the observed build issue and hopefully preventing
future issues as headers are refactored.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Mark Brown <broonie@kernel.org>
Acked-by: Steve Capper <steve.capper@linaro.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
PCI IO space was intended to be 16MiB, at 32MiB below MODULES_VADDR, but
commit d1e6dc91b5 ("arm64: Add architectural support for PCI")
extended this to cover the full 32MiB. The final 8KiB of this 32MiB is
also allocated for the fixmap, allowing for potential clashes between
the two.
This change was masked by assumptions in mem_init and the page table
dumping code, which assumed the I/O space to be 16MiB long through
seaparte hard-coded definitions.
This patch changes the definition of the PCI I/O space allocation to
live in asm/memory.h, along with the other VA space allocations. As the
fixmap allocation depends on the number of fixmap entries, this is moved
below the PCI I/O space allocation. Both the fixmap and PCI I/O space
are guarded with 2MB of padding. Sites assuming the I/O space was 16MiB
are moved over use new PCI_IO_{START,END} definitions, which will keep
in sync with the size of the IO space (now restored to 16MiB).
As a useful side effect, the use of the new PCI_IO_{START,END}
definitions prevents a build issue in the dumping code due to a (now
redundant) missing include of io.h for PCI_IOBASE.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
[catalin.marinas@arm.com: reorder FIXADDR and PCI_IO address_markers_idx enum]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Since c9465b4ec3 (arm64: add support to dump the kernel page tables)
allmodconfig has failed to build on arm64 as a result of:
../arch/arm64/mm/dump.c:55:20: error: 'PCI_IOBASE' undeclared here (not in a function)
Fix this by explicitly including io.h to ensure that a definition is
present.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
If the final page table entry we walk is a valid mapping, the page table
dumping code will not log the region this entry is part of, as the final
note_page call in ptdump_show will trigger an early return. Luckily this
isn't seen on contemporary systems as they typically don't have enough
RAM to extend the linear mapping right to the end of the address space.
In note_page, we log a region when we reach its end (i.e. we hit an
entry immediately afterwards which has different prot bits or is
invalid). The final entry has no subsequent entry, so we will not log
this immediately. We try to cater for this with a subsequent call to
note_page in ptdump_show, but this returns early as 0 < LOWEST_ADDR, and
hence we will skip a valid mapping if it spans to the final entry we
note.
Unlike 32-bit ARM, the pgd with the kernel mapping is never shared with
user mappings, so we do not need the check to ensure we don't log user
page tables. Due to the way addr is constructed in the walk_* functions,
it can never be less than LOWEST_ADDR when walking the page tables, so
it is not necessary to avoid dereferencing invalid table addresses. The
existing checks for st->current_prot and st->marker[1].start_address are
sufficient to ensure we will not print and/or dereference garbage when
trying to log information.
This patch removes the unnecessary check against LOWEST_ADDR, ensuring
we log all regions in the kernel page table, including those which span
right to the end of the address space.
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Laura Abbott <lauraa@codeaurora.org>
Acked-by: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When building with 48-bit VAs, it's possible to get the following
warning when building the arm64 page table dumping code:
arch/arm64/mm/dump.c: In function ‘walk_pgd’:
arch/arm64/mm/dump.c:266:2: warning: right shift count >= width of type
pgd_t *pgd = pgd_offset(mm, 0);
^
As pgd_offset is a macro and the second argument is not cast to any
particular type, the zero will be given integer type by the compiler.
As pgd_offset passes the pargument to pgd_index, we then try to shift
the 32-bit integer by at least 39 bits (for 4k pages).
Elsewhere the pgd_offset is passed a second argument of unsigned long
type, so let's do the same here by passing '0UL' rather than '0'.
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Laura Abbott <lauraa@codeaurora.org>
Acked-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
In a similar manner to arm, it's useful to be able to dump the page
tables to verify permissions and memory types. Add a debugfs file
to check the page tables.
Acked-by: Steve Capper <steve.capper@linaro.org>
Tested-by: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
[will: s/BUFFERABLE/NORMAL-NC/]
Signed-off-by: Will Deacon <will.deacon@arm.com>
