There is just no point mapping up to 512MB for a serial port.
Using a single 1MB entry is way sufficient for all users.
This will create less interference for the following debugging patch.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This is a very simple method for code running in an emulator, or under
the supervision of a debugger, to use I/O facilities on the controlling
host.
Tested with OpenOCD, and ARM's Fast Models.
Details on semihosting can be found in chapter 8 of
DUI0203I_rvct_developer_guide.pdf from ARM Ltd.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch adds a check for the presence of the LPAE feature during the
CPU initialisation. If not present, it reports an error when
CONFIG_DEBUG_LL is enabled.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch adds the MMU initialisation for the LPAE page table format.
The swapper_pg_dir size with LPAE is 5 rather than 4 pages. A new
proc-v7-3level.S file contains the TTB initialisation, context switch
and PTE setting code with the LPAE. The TTBRx split is based on the
PAGE_OFFSET with TTBR1 used for the kernel mappings. The 36-bit mappings
(supersections) and a few other memory types in mmu.c are conditionally
compiled.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Before we enable the MMU, we must ensure that the TTBR registers contain
sane values. After the MMU has been enabled, we jump to the *virtual*
address of the following function, so we also need to ensure that the
SCTLR write has taken effect.
This patch adds ISB instructions around the SCTLR write to ensure the
visibility of the above.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The ARM SMP booting code allocates a temporary set of page tables
containing an identity mapping of the kernel image and provides this
to secondary CPUs for initial booting.
In reality, we only need to include the __turn_mmu_on function in the
identity mapping since the rest of the kernel is executing from virtual
addresses after this point.
This patch adds __turn_mmu_on to the .idmap.text section, allowing the
SMP booting code to use the idmap_pgd directly and not have to populate
its own set of page table.
As a result of this patch, we can make the identity_mapping_add function
static (since it is only used within mm/idmap.c) and also remove the
identity_mapping_del function. The identity map population is moved to
an early initcall so that it is setup in time for secondary CPU bringup.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
__create_page_tables identity maps the region of memory from
__enable_mmu to the end of __turn_mmu_on.
In preparation for including __turn_mmu_on in the .idmap.text section,
this patch modifies the identity mapping so that it only includes the
__turn_mmu_on code.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Recent gcc versions generate unaligned accesses by default on ARMv6 and
later processors. This patch ensures that the SCTLR.A bit is always
cleared on such processors to avoid kernel traping before
alignment_init() is called.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: John Linn <John.Linn@xilinx.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When the CONFIG_NO_MACH_MEMORY_H symbol is selected by a particular
machine class, the machine specific memory.h include file is no longer
used and can be removed. In that case the equivalent information can
be obtained dynamically at runtime by enabling CONFIG_ARM_PATCH_PHYS_VIRT
or by specifying the physical memory address at kernel configuration time.
If/when all instances of mach/memory.h are removed then this symbol could
be removed.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Some platforms (like OMAP not to name it) are doing rather complicated
hacks just to determine the base UART address to use. Let's give their
addruart macro some slack by providing an extra work register which will
allow for much needed cleanups.
This is basically a no-op as this commit is only adding the extra argument
to the macro but no one is using it yet.
Signed-off-by: nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Kevin Hilman <khilman@ti.com>
PGDIR_SHIFT and PMD_SHIFT for the classic 2-level page table format have
the same value (21). This patch converts the PGDIR_* uses in the kernel
to the PMD_* equivalent so that LPAE builds can reuse the same code.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Currently, the documented kernel entry requirements are not
explicit about whether the kernel should be entered in ARM or
Thumb, leading to an ambiguitity about how to enter Thumb-2
kernels. As a result, the kernel is reliant on the zImage
decompressor to enter the kernel proper in the correct instruction
set state.
This patch changes the boot entry protocol for head.S and Image to
be the same as for zImage: in all cases, the kernel is now entered
in ARM.
Documentation/arm/Booting is updated to reflect this new policy.
A different rule will be needed for Cortex-M class CPUs as and when
support for those lands in mainline, since these CPUs don't support
the ARM instruction set at all: a note is added to the effect that
the kernel must be entered in Thumb on such systems.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch makes TTBR1 point to swapper_pg_dir so that global, kernel
mappings can be used exclusively on v6 and v7 cores where they are
needed.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The dtb is passed to the kernel via register r2, which is the same
method that is used to pass an atags pointer. This patch modifies
__vet_atags to not clear r2 when it encounters a dtb image.
v2: fixed bugs pointed out by Nicolas Pitre
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Adding Thumb2 support to the runtime patching of the virt_to_phys and
phys_to_virt opcodes.
Tested both the 8-bit and the 16-bit fixups, using different placements
in memory to exercize all code paths.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
If ATAGs or DTB pointer is not within first 1MB of RAM, then the boot params
will not be mapped early enough, so map the 1MB region that r2 points to. Only
map the first 1MB when r2 is 0.
Some assembly improvements from Nicolas Pitre.
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
