The 32-bit conditional branches in Thumb-2 have a shorter range
(+/-512K) than their ARM counterparts (+/-32MB).  The linker does
not currently generate trampolines to extend the range of these
Thumb-2 conditional branches, resulting in link errors when vmlinux
is sufficiently large, e.g.:

head.o:(.text+0x464): relocation truncated to fit: R_ARM_THM_JUMP19

This patch forces the longer-range, unconditional branch encoding
by use of an explicit IT instruction.  The resulting branches are
triggered on the same conditions as before.
Signed-off-by: NDave Martin <dave.martin@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Directives such as .long and .word do not magically cause the
assembler location counter to become aligned in gas.  As a result,
using these directives in code sections can result in misaligned
data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL).

This is a Bad Thing, since the ABI permits the compiler to assume
that fundamental types of word size or above are word- aligned when
accessing them from C.  If the data is not really word-aligned,
this can cause impaired performance and stray alignment faults in
some circumstances.

In general, the following rules should be applied when using data
word declaration directives inside code sections:

    * .quad and .double:
         .align 3

    * .long, .word, .single, .float:
         .align (or .align 2)

    * .short:
        No explicit alignment required, since Thumb-2
        instructions are always 2 or 4 bytes in size.
        immediately after an instruction.
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NDave Martin <dave.martin@linaro.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Since we can get both physical and virtual addresses from the addruart
macro, we can use this to establish the debug mappings.

In the case of CONFIG_DEBUG_ICEDCC, we don't need any mappings, but
may still need to setup r7 correctly.

Incorporating ASM changes from Nicolas Pitre <npitre@fluxnic.net>.
Signed-off-by: NJeremy Kerr <jeremy.kerr@canonical.com>
Tested-by: NKevin Hilman <khilman@deeprootsystems.com>

Add some additional documentation on register usage in __enable_mmu
to help complete the overall picture.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move these two functions, both of which are required for secondary
CPU booting, into the cpuinit section.  Ensure bad processors call
__error_p for better diagnostics, rather than just __error.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

__enable_mmu is required to be executed in an identity mapped region
to ensure that variances in CPUs do not cause a crash.  We currently
achieve this by assuming that it will be co-located with
__create_page_tables.  With hotplug CPU support, this assumption
becomes invalid.  Implement a better solution which ensures that
it will be appropriately mapped no matter where it is placed.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This allows us to relocate __mmap_switched and associated data away
from the head section.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

UP systems do not implement all the instructions that SMP systems have,
so in order to boot a SMP kernel on a UP system, we need to rewrite
parts of the kernel.

Do this using an 'alternatives' scheme, where the kernel code and data
is modified prior to initialization to replace the SMP instructions,
thereby rendering the problematical code ineffectual.  We use the linker
to generate a list of 32-bit word locations and their replacement values,
and run through these replacements when we detect a UP system.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This has the consequence of changing the section name used for head
code from ".text.head" to ".head.text".  Since this commit changes all
users in the architecture, this change should be harmless.

The .text.head output section is eliminated and the head text code is
included at the start of the .init output section.
Signed-off-by: NTim Abbott <tabbott@ksplice.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch implements the ARM/Thumb-2 unified kernel start-up and
exception handling code.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

This declaration specifies the "function" type and size for various
assembly functions, mainly needed for generating the correct branch
instructions in Thumb-2.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move the definitions of ATAG_CORE and ATAG_CORE_SIZE in head.S to
head-common.S. There is no use of these in head.S itself, but they
are used in head-common.S. When building for the !CONFIG_MMU case
these were not defined when compiling head-nommu.S (which includes
head-common.S).
Signed-off-by: NGreg Ungerer <gerg@uclinux.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Examines the ATAGS pointer (r2) at boot, and interprets
a nonzero value as a reference to an ATAGS structure. A
suitable ATAGS structure replaces the kernel's command line.
Signed-off-by: NBill Gatliff <bgat@billgatliff.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Commit 86c0baf1 highlighted that we
may end up with the head text placed elsewhere in the kernel image.
Introduce a new .text.head section to contain the initial kernel
startup code, and always place this section at the beginning of the
kernel image.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Let's surround constructs like:

	orr	r3, r3, #(KERNEL_RAM_PADDR & 0x00f00000)

between .if .endif since (KERNEL_RAM_PADDR & 0x00f00000) is 0 in 99% of
all cases.

Also let's mask PHYS_OFFSET with 0x00f00000 instead of 0x00e00000.
Section mappings are really 1MB not 2MB and the 2MB groupping is
a higher level issue already much better enforced with

#if (PHYS_OFFSET & 0x001fffff)
#error "PHYS_OFFSET must be at an even 2MiB boundary!"
#endif

at the top of the file.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

 aware

Since TEXT_OFFSET is meant to determine RAM location for kernel use,
itshould affect .data and .bss initial mapping in the XIP case.
Otherwise a XIP kernel would crash if TEXT_OFFSET gets somewhat larger
than 2MB.

Corresponding code is also moved up a bit to be near the similar .text
mapping code making the whole a bit more straight forward to understand.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Since commit 2552fc27 XIP kernels failed
to boot because (_end - PAGE_OFFSET - 1) is much smaller than the size
of the kernel text and data in the XIP case, causing the kernel not to
be entirely mapped.

Even in the non-XIP case, the use of (_end - PAGE_OFFSET - 1) is wrong
because it produces a too large value if TEXT_OFFSET is larger than 1MB.

Finally the original code was performing one loop too many.

Let's break the loop when the section pointer has passed the last byte
of the kernel instead.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patchs allows the offset to the first page of
physical memory to be on any 2MB boundary
whereas the previous code could only handle psysical
offset to any 16MB boundary (0xNN000000) or any 1MB
boundary below 0x01000000 (e.g. 0x00N00000). The
problem is a consequence of the orr one-byte syntax,
so we fix this and we can place the first bank of
memory at 0x28e00000. I have also included an explicit
check that disallow compilation when PHYS_OFFSET is
not on a 2MiB boundary. head.S would be the proper place
to have this at since this is the first file that
attempts to use PHYS_OFFSET during compile.
Signed-off-by: NLinus Walleij <triad@df.lth.se>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Clean up the KERNEL_RAM_ADDR stuff in arch/arm/kernel/head.S to
make it clearer what's referring to what.  In doing so, remove
the usage of __virt_to_phys(), which is not guaranteed to be
something that the assembler can parse.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

These files want to provide/access ELF hwcap information, so should
be including asm/elf.h rather than asm/procinfo.h
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We currently have a hardcoded 4 megabyte uncompressed kernel image
size limit, which is easily exceeded by, for example, enabling some of
the various kernel debugging options.

When setting up the initial page tables (which is where this 4M limit
is hardcoded), it's actually relatively easy to find out the true size
of the uncompressed kernel image and create enough page table entries
for things to fit, so this patch makes it so.

In the decompressor, we also need to know the size of the uncompressed
kernel image, to figure out whether there is any chance that uncompressing
the kernel might overwrite the compressed kernel image stored elsewhere
in memory. We don't have that info at this boot stage, though, so we
approximate the size of the uncompressed kernel by taking the compressed
kernel image size and allowing for a maximum 4x expansion.
Signed-off-by: NLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Catalin Marinas

This is instead of a magic number.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Processor support files now use r6 in their CPU setup code, so
we can't rely on r6 being preserved.  Use r7 instead.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

On some CPUs, bit 4 of section mappings means "update the
cache when written to".  On others, this bit is required to
be one, and others it's required to be zero.  Finally, on
ARMv6 and above, setting it turns on "no execute" and prevents
speculative prefetches.

With all these combinations, no one value fits all CPUs, so we
have to pick a value depending on the CPU type, and the area
we're mapping.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

DEFAULT_FIQ was entirely unused.  MODE_* are just redefinitions
of *_MODE.  Use *_MODE instead.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Uwe Zeisberger

added the following constants:
- MACHINFO_TYPE
- MACHINFO_NAME
- MACHINFO_PHYSIO
- MACHINFO_PGOFFIO
- PROCINFO_INITFUNC
- PROCINFO_MMUFLAGS

and removed their definition from head.S and head-nommu.S
Signed-off-by: NUwe Zeisberger <Uwe_Zeisberger@digi.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch adds nommu version start-up code head-nommu.S.
The common part of the start-up codes is moved to head-common.S.
Signed-off-by: NHyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Nicolas Pitre

This field is redundent since it must be equal to PHYS_OFFSET anyway.

There is no reference to it anymore so remove it at last.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Read the processor ID at boot, and save it in "processor_id" as we
did before.  Later, when we re-parse the CPU type in the setup.c code,
re-use the value stored in "processor_id".

This allows a cleaner work-around for noMMU devices without CP#15.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Nicolas Pitre

This field is redundent since it must be equal to PHYS_OFFSET anyway.

First, let's  use PHYS_OFFSET directly instead.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We are coding the kernel link address into the makefiles, which is
invisibly dependent on PAGE_OFFSET.  If PAGE_OFFSET is changed, the
makefiles also need to be changed.

Make adjustments such that the makefiles encode just the offset from
PAGE_OFFSET for the kernel link address, and use PAGE_OFFSET in the
linker scripts directly.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We don't really need to check whether the machine type is Netwinder
or CATS before setting up the PCI IO mapping for debugging.  This
allows us to eliminate asm/mach-types.h from head.S
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Nicolas Pitre

Since vmlinux.lds.S is preprocessed, we can use the defines already
present in asm/memory.h (allowed by patch #3060) for the XIP kernel link
address instead of relying on a duplicated Makefile hardcoded value, and
also get rid of its dependency on awk to handle it at the same time.

While at it let's clean XIP stuff even further and make things clearer
in head.S with a nice code reduction.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Patch from Nicolas Pitre

This patch allows for assorted type of cleanups by letting assembly code
use the same set of defines for constant values and avoid duplicated
definitions that might not always be in sync, or that might simply be
confusing due to the different names for the same thing.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Delete obsoleted stuff from arch Makefile and rename
constants.h to asm-offsets.h
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

Make the magic address values in head.S more obvious as to where
they came from.  Wrap all debug code in CONFIG_DEBUG_LL.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Create a temporary page table to startup secondary processors.  This
page table must have a 1:1 virtual/physical mapping for the kernel
in addition to the standard mappings to ensure that the secondary
CPU can enable its MMU safely.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Various places in the ARM kernel implicitly assumed that kernel
stacks are always 8K due to hard coded constants.  Replace these
constants with definitions.

Correct the allowable range of kernel stack pointer values within
the allocation.  Arrange for the entire kernel stack to be zeroed,
not just the upper 4K if CONFIG_DEBUG_STACK_USAGE is set.
Signed-off-by: NRussell King <rmk@arm.linux.org.uk>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!