MFC 265852: Map device memory using PTE_DEVICE rather than PTE_NOCACHE.

MFC 262952, 262958, 262966, 262979, 262980, 262986, 262987, 262995, 262997,
263030, 263033, 263034, 263056, 263057,

Remove all the redundant external declarations of exception vectors and
runtime setting of the pointers that's scattered around various places.

Remove all traces of support for ARM chips prior to the arm9 series.

Make the default exception handler vectors point to where I thought they
were already pointing: the default handlers (not a panic that says there
is no default handler).

Eliminate irq_dispatch.S. Move the data items it contained into
arm/intr.c and the functionality it provided into arm/exception.S.

Move the exception vector table (so-called "page0" data) into exception.S
and eliminate vectors.S.

Change the way the asm GET_CURTHREAD_PTR() macro is defined so that code
using it doesn't have to have an "AST_LOCALS" macro somewhere in the file.

Arrange for arm fork_trampoline() to return to userland via the standard
swi_exit code in exception.S instead of having its own inline expansion
of the DO_AST and PULLFRAME macros.

Now that the PUSHFRAME and PULLFRAME macros are used only in the swi
entry/exit code, they don't need to be macros. Except that didn't work
and the whole change was reverted.

Remove some unnecessary indirection and jump right to the handler functions.

Use panic rather than printf to "handle" an arm26 address exception
(should never happen on arm32).

Remove the unreferenced DATA() macro.

Remove #include <machine/asmacros.h> from files that don't need it.

MFC r261643, r261646, r261648, r261649, r261651, r261656, r261657, r261663,
r261676, r261677, r261698, r261778

Consolidate code related to setting up physical memory configuration into
a new physmem.c file.

Replace compile-time constant KERNPHYSADDR with abp_physaddr

Calculate the kernel's load address from the PC in the elf / gzip
trampoline instead of relying on KERNPHYSADDR as a compile-time constant.

It turns out a global variable is the only straightforward way to
communicate the kernel's physical load address from where it's known in
initarm() into cpu_mp_start() which is called from non-arm code and
takes no parameters.

Remove the now unused MMU_INIT macro.

Use vm_paddr_t, not vm_offset_t, when dealing with physical addresses.

No need to set physmem in each initarm() instance anymore, it's handled
in common code now.

Pass the pagetable used from locore.S to initarm to allow it to map data
in as required.

Fix the physmem exclude-region clipping logic for the edge-trim case.

Add some extra debugging output when DEBUG is defined.

Update legacy platforms to use new arm_physmem helper routines.

MFC r257549, r261642

Don't create a distinct free page pool for segregating allocations that are
accessed through the direct map unless the kernel configuration actually
includes a direct map. Only a few configurations do, and for the rest the
unnecessary free page pool is a small pessimization.

Remove the ARM_USE_SMALL_ALLOC option and code related to it.

MFC r258392, r258412:

Call cpu_setup() immediately after the page tables are installed. This
enables data cache and other chip-specific features. It was previously
done via an early SYSINIT, but it was being done after pmap and vm setup,
and those setups need to use mutexes. On some modern ARM platforms,
the ldrex/strex instructions that implement mutexes require the data cache
to be enabled.

Call cpu_setup() from the initarm() routine on platforms that don't use
the common FDT-aware initarm() in arm/machdep.c.

MFC r257648, r257649, r257660:

Begin reducing code duplication in arm pmap.c and pmap-v6.c by factoring
out common code related to mapping device memory into a new devmap.c file.

Remove the growing duplication of code that used pmap_devmap_find_pa() and
then did some math with the returned results to generate a virtual address,
and likewise in reverse to get a physical address. Now there are a pair
of functions, arm_devmap_vtop() and arm_devmap_ptov(), to do that. The
bus_space_map() implementations are rewritten in terms of these.

Move remaining code and data related to static device mapping into the
new devmap.[ch] files. Emphasize the MD nature of these things by using
the prefix arm_devmap_ on the function and type names (already a few of
these things found their way into MI code, hopefully it will be harder to
do by accident in the future).

MFC 265852: Map device memory using PTE_DEVICE rather than PTE_NOCACHE.

MFC 262952, 262958, 262966, 262979, 262980, 262986, 262987, 262995, 262997,
263030, 263033, 263034, 263056, 263057,

Remove all the redundant external declarations of exception vectors and
runtime setting of the pointers that's scattered around various places.

Remove all traces of support for ARM chips prior to the arm9 series.

Make the default exception handler vectors point to where I thought they
were already pointing: the default handlers (not a panic that says there
is no default handler).

Eliminate irq_dispatch.S. Move the data items it contained into
arm/intr.c and the functionality it provided into arm/exception.S.

Move the exception vector table (so-called "page0" data) into exception.S
and eliminate vectors.S.

Change the way the asm GET_CURTHREAD_PTR() macro is defined so that code
using it doesn't have to have an "AST_LOCALS" macro somewhere in the file.

Arrange for arm fork_trampoline() to return to userland via the standard
swi_exit code in exception.S instead of having its own inline expansion
of the DO_AST and PULLFRAME macros.

Now that the PUSHFRAME and PULLFRAME macros are used only in the swi
entry/exit code, they don't need to be macros. Except that didn't work
and the whole change was reverted.

Remove some unnecessary indirection and jump right to the handler functions.

Use panic rather than printf to "handle" an arm26 address exception
(should never happen on arm32).

Remove the unreferenced DATA() macro.

Remove #include <machine/asmacros.h> from files that don't need it.

MFC r261643, r261646, r261648, r261649, r261651, r261656, r261657, r261663,
r261676, r261677, r261698, r261778

Consolidate code related to setting up physical memory configuration into
a new physmem.c file.

Replace compile-time constant KERNPHYSADDR with abp_physaddr

Calculate the kernel's load address from the PC in the elf / gzip
trampoline instead of relying on KERNPHYSADDR as a compile-time constant.

It turns out a global variable is the only straightforward way to
communicate the kernel's physical load address from where it's known in
initarm() into cpu_mp_start() which is called from non-arm code and
takes no parameters.

Remove the now unused MMU_INIT macro.

Use vm_paddr_t, not vm_offset_t, when dealing with physical addresses.

No need to set physmem in each initarm() instance anymore, it's handled
in common code now.

Pass the pagetable used from locore.S to initarm to allow it to map data
in as required.

Fix the physmem exclude-region clipping logic for the edge-trim case.

Add some extra debugging output when DEBUG is defined.

Update legacy platforms to use new arm_physmem helper routines.

MFC r257549, r261642

Don't create a distinct free page pool for segregating allocations that are
accessed through the direct map unless the kernel configuration actually
includes a direct map. Only a few configurations do, and for the rest the
unnecessary free page pool is a small pessimization.

Remove the ARM_USE_SMALL_ALLOC option and code related to it.

MFC r258392, r258412:

Call cpu_setup() immediately after the page tables are installed. This
enables data cache and other chip-specific features. It was previously
done via an early SYSINIT, but it was being done after pmap and vm setup,
and those setups need to use mutexes. On some modern ARM platforms,
the ldrex/strex instructions that implement mutexes require the data cache
to be enabled.

Call cpu_setup() from the initarm() routine on platforms that don't use
the common FDT-aware initarm() in arm/machdep.c.

MFC r257648, r257649, r257660:

Begin reducing code duplication in arm pmap.c and pmap-v6.c by factoring
out common code related to mapping device memory into a new devmap.c file.

Remove the growing duplication of code that used pmap_devmap_find_pa() and
then did some math with the returned results to generate a virtual address,
and likewise in reverse to get a physical address. Now there are a pair
of functions, arm_devmap_vtop() and arm_devmap_ptov(), to do that. The
bus_space_map() implementations are rewritten in terms of these.

Move remaining code and data related to static device mapping into the
new devmap.[ch] files. Emphasize the MD nature of these things by using
the prefix arm_devmap_ on the function and type names (already a few of
these things found their way into MI code, hopefully it will be harder to
do by accident in the future).