To cope with the variety in ARM architectures and configurations, the
pagetable attributes for kernel memory are generated at runtime to match
the system the kernel finds itself on. This calculated value is stored
in pgprot_kernel.
However, when early fixmap support was added for ARM (commit
a5f4c561b3) the attributes used for mappings were hard coded because
pgprot_kernel is not set up early enough. Unfortunately, when fixmap is
used after early boot this means the memory being mapped can have
different attributes to existing mappings, potentially leading to
unpredictable behaviour. A specific problem also exists due to the hard
coded values not include the 'shareable' attribute which means on
systems where this matters (e.g. those with multiple CPU clusters) the
cache contents for a memory location can become inconsistent between
CPUs.
To resolve these issues we change fixmap to use the same memory
attributes (from pgprot_kernel) that the rest of the kernel uses. To
enable this we need to refactor the initialisation code so
build_mem_type_table() is called early enough. Note, that relies on early
param parsing for memory type overrides passed via the kernel command
line, so we need to make sure this call is still after
parse_early_params().
[ardb: keep early_fixmap_init() before param parsing, for earlycon]
Fixes: a5f4c561b3 ("ARM: 8415/1: early fixmap support for earlycon")
Cc: <stable@vger.kernel.org> # v4.3+
Tested-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This enables the generic early_ioremap implementation for ARM.
It uses the fixmap region reserved for kmap. Since early_ioremap
is only supported before paging_init(), and kmap is only supported
afterwards, this is guaranteed not to cause any clashes.
Tested-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Add early fixmap support, initially to support permanent, fixed
mapping support for early console. A temporary, early pte is
created which is migrated to a permanent mapping in paging_init.
This is also needed since the attributes may change as the memory
types are initialized. The 3MiB range of fixmap spans two pte
tables, but currently only one pte is created for early fixmap
support.
Re-add FIX_KMAP_BEGIN to the index calculation in highmem.c since
the index for kmap does not start at zero anymore. This reverts
4221e2e6b3 ("ARM: 8031/1: fixmap: remove FIX_KMAP_BEGIN and
FIX_KMAP_END") to some extent.
Cc: Mark Salter <msalter@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Use fixmaps for text patching when the kernel text is read-only,
inspired by x86. This makes jump labels and kprobes work with the
currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming
CONFIG_DEBUG_RODATA options.
Signed-off-by: Rabin Vincent <rabin@rab.in>
[kees: fixed up for merge with "arm: use generic fixmap.h"]
[kees: added parse acquire/release annotations to pass C=1 builds]
[kees: always use stop_machine to keep TLB flushing local]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h.
Also makes sure that the fixmap allocation fits into the expected range.
Based on patch by Rabin Vincent.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rabin Vincent <rabin@rab.in>
Acked-by: Nicolas Pitre <nico@linaro.org>
With commit a05e54c103 ("ARM: 8031/2: change fixmap mapping region to
support 32 CPUs"), the fixmap region was expanded to 2MB, but it
precluded any other uses of the fixmap region. In order to support other
uses the fixmap region needs to be expanded beyond 2MB. Fortunately, the
adjacent 1MB range 0xffe00000-0xfff00000 is availabe.
Remove fixmap_page_table ptr and lookup the page table via the virtual
address so that the fixmap region can span more that one pmd. The 2nd
pmd is already created since it is shared with the vector page.
Signed-off-by: Rob Herring <robh@kernel.org>
[kees: fixed CONFIG_DEBUG_HIGHMEM get_fixmap() calls]
[kees: moved pte allocation outside of CONFIG_HIGHMEM]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
ARM is different from other architectures in that fixmap pages are indexed
with a positive offset from FIXADDR_START. Other architectures index with
a negative offset from FIXADDR_TOP. In order to use the generic fixmap.h
definitions, this patch redefines FIXADDR_TOP to be inclusive of the
useable range. That is, FIXADDR_TOP is the virtual address of the topmost
fixed page. The newly defined FIXADDR_END is the first virtual address
past the fixed mappings.
Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
[kees: update for a05e54c103 ("ARM: 8031/2: change fixmap ...")]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Rob Herring <robh@kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
In 32-bit ARM systems, the fixmap mapping region can support no more
than 14 CPUs(total: 896k; one CPU: 64K). And we can configure NR_CPUS
up to 32. So there is a mismatch.
This patch moves fixmapping region downwards to region 0xffc00000-
0xffe00000. Then the fixmap mapping region can support up to 32 CPUs.
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Liu Hua <sdu.liu@huawei.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
It seems that these two macros are not used by non architecture
specific code. And on ARM FIX_KMAP_BEGIN equals zero.
This patch removes these two macros. Instead, using FIX_KMAP_NR_PTES to
tell the pte number belonged to fixmap mapping region. The code will
become clearer when I introduce a bugfix on fixmap mapping region.
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Liu Hua <sdu.liu@huawei.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This is the minimum fixmap interface expected to be implemented by
architectures supporting highmem.
We have a second level page table already allocated and covering
0xfff00000-0xffffffff because the exception vector page is located
at 0xffff0000, and various cache tricks already use some entries above
0xffff0000. Therefore the PTEs covering 0xfff00000-0xfffeffff are free
to be used.
However the XScale cache flushing code already uses virtual addresses
between 0xfffe0000 and 0xfffeffff.
So this reserves the 0xfff00000-0xfffdffff range for fixmap stuff.
The Documentation/arm/memory.txt information is updated accordingly,
including the information about the actual top of DMA memory mapping
region which didn't match the code.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
