Re: [PATCH 00/58] Add support for Enhanced Virtual Addressing

[David Daney <ddaney.cavm@gmail.com>]

This whole thing seems very messy.  I see a couple of problems:

1) There are if(CONFIG_EVA) ... else ... endif  all over the place.  It 
is very ugly.

2) You cannot have a signel kernel with both EVA and non-EVA support.

Have you considered just tagging all the instructions that touch the 
user address space, and patching them at system boot with their EVA 
equivalents if EVA support is desired?

You might even be able to use the existing exception tables and not have 
to add a special table for EVA.  The instructions that can trap are 
exactly those where the EVA version should be used.

David Daney



On 01/27/2014 12:18 PM, Markos Chandras wrote:
> Hi,
>
> This patchset adds support for the Enhanced Virtual Addressing feature
> of the MIPS 3.5 ISA currently present in the *Aptiv processors.
> In Release 3, the memory architecture defines the partitioning of memory
> space into fixed‐size segments, whose access properties and cacheability
> attributes are programmable. The "mapped" and "unmapped" segment‐access
> properties can now be modified so as to extend system memory space
> (kseg0/kseg1) to include unmapped access to user space (xkseg), a
> feature called Enhanced Virtual Addressing (EVA). Instructions that
> facilitate system read/write access to xkseg have also been added to the
> R3 ISA (lwe, swe, lbue, etc).
>
> This patchset also adds EVA support for the Malta board. The unmapped
> address space (kseg0/kseg1) has been extended to 2GB.
>
> If you want to try it, you can use the 'eva-next' branch on
> the following git repository
>
> https://github.com/hwoarang/linux.git eva-next
>
> The patchset applies on top of the upstream-sfr/mips-for-linux-next tree.
>
> Leonid Yegoshin (18):
>    MIPS: Kconfig: Add Kconfig symbols for EVA support
>    MIPS: asm: Add prefetch instruction for EVA
>    MIPS: uapi: inst: Add new EVA opcodes
>    MIPS: uapi: inst: Add instruction format for SPECIAL3 instructions
>    MIPS: traps: Set correct address limit for breakpoints and traps
>    MIPS: asm: uaccess: Disable unaligned access macros for EVA
>    MIPS: kernel: unaligned: Handle unaligned accesses for EVA
>    MIPS: asm: checksum: Split kernel and user copy operations
>    MIPS: asm: checksum: Add MIPS specific csum_and_copy_from_user
>      function
>    MIPS: kernel: signal: Prevent save/restore FPU context in user memory
>    MIPS: asm: r4kcache: Build flushing code for instruction cache
>    MIPS: asm: r4kcache: Add protected cache operation for EVA
>    MIPS: asm: r4kcache: Add EVA cache flushing functions
>    MIPS: kernel: {ftrace,kgdb}: Set correct address limit for cache
>      flushes
>    MIPS: asm: page: Allow __pa_symbol overrides
>    MIPS: mm: c-r4k: Build EVA {d,i}cache flushing functions
>    MIPS: mm: c-r4k: Flush scache to avoid cache aliases
>    MIPS: malta: malta-init: Fix System Controller memory mapping for EVA
>
> Markos Chandras (40):
>    MIPS: asm: Add wrappers for EVA/non-EVA instructions
>    MIPS: futex: Add EVA support for futex operations
>    MIPS: kernel: scall32-o32: Use EVA wrappers to fetch syscall arguments
>    MIPS: kernel: traps: Whitespace clean up
>    MIPS: lib: strnlen_user: Use macro to build the strnlen_user symbol
>    MIPS: lib: strnlen_user: Add EVA support
>    MIPS: lib: strlen_user: Use macro to build the strlen_user symbol
>    MIPS: lib: strlen_user: Add EVA support
>    MIPS: lib: strncpy_user: Use macro to build the strncpy_from_user
>      symbol
>    MIPS: lib: strncpy_user: Add EVA support
>    MIPS: lib: memcpy: Merge EXC and load/store macros
>    MIPS: lib: memcpy: Split source and destination prefetch macros
>    MIPS: lib: memcpy: Use macro to build the copy_user code
>    MIPS: lib: memcpy: Add EVA support
>    MIPS: lib: memset: Whitespace fixes
>    MIPS: lib: memset: Use macro to build the __bzero symbol
>    MIPS: lib: memset: Add EVA support for the __bzero function.
>    MIPS: asm: uaccess: Add instruction argument to __{put,get}_user_asm
>    MIPS: asm: uaccess: Move duplicated code to common function
>    MIPS: asm: uaccess: Use EVA instructions wrappers
>    MIPS: asm: uaccess: Rename {get,put}_user_asm macros
>    MIPS: asm: uaccess: Add EVA support to copy_{in, to,from}_user
>    MIPS: asm: uaccess: Add EVA support for str*_user operations
>    MIPS: kernel: unaligned: Add EVA instruction wrappers
>    MIPS: checksum: Split the 'copy_user' symbol
>    MIPS: lib: csum_partial: Merge EXC and load/store macros
>    MIPS: lib: csum_partial: Add macro to build csum_partial symbols
>    MIPS: lib: csum_partial: Add EVA support
>    MIPS: asm: cpu: Add cpu flag for Enhanced Virtual Addressing
>    MIPS: kernel: cpu-probe: Enable EVA option on supported cores
>    MIPS: kernel: proc: Add EVA to the list of CPU features
>    MIPS: mm: init: Add free_init_pages() callback for EVA
>    MIPS: mm: c-r4k: Add support for flushing user pages from cache
>    MIPS: malta: Configure Segment Control registers for EVA boot
>    MIPS: malta: spaces.h: Add spaces.h file for Malta (EVA)
>    MIPS: malta: malta-memory: Add support for the 'ememsize' variable
>    MIPS: malta: malta-memory: Use the PHYS_OFFSET to build the memory map
>    MIPS: malta: malta-memory: Add free_init_pages_eva() callback
>    MIPS: malta: Add support for SMP EVA
>    MIPS: Enable MIPS 3.5 features on Malta
>
>   arch/mips/Kconfig                                  |  29 +-
>   arch/mips/include/asm/asm.h                        | 130 +++++
>   arch/mips/include/asm/bootinfo.h                   |   2 +
>   arch/mips/include/asm/checksum.h                   |  44 +-
>   arch/mips/include/asm/cpu-features.h               |   4 +-
>   arch/mips/include/asm/cpu.h                        |   1 +
>   arch/mips/include/asm/futex.h                      |   9 +-
>   arch/mips/include/asm/fw/fw.h                      |   2 +-
>   .../include/asm/mach-malta/kernel-entry-init.h     | 115 ++++-
>   arch/mips/include/asm/mach-malta/spaces.h          |  46 ++
>   arch/mips/include/asm/page.h                       |   2 +
>   arch/mips/include/asm/r4kcache.h                   | 173 ++++++-
>   arch/mips/include/asm/uaccess.h                    | 559 ++++++++++++++++-----
>   arch/mips/include/uapi/asm/inst.h                  |  25 +-
>   arch/mips/kernel/cpu-probe.c                       |   3 +
>   arch/mips/kernel/ftrace.c                          |   4 +
>   arch/mips/kernel/head.S                            |   2 +-
>   arch/mips/kernel/kgdb.c                            |  17 +-
>   arch/mips/kernel/mips_ksyms.c                      |  24 +-
>   arch/mips/kernel/proc.c                            |   1 +
>   arch/mips/kernel/scall32-o32.S                     |   9 +-
>   arch/mips/kernel/signal.c                          |  26 +
>   arch/mips/kernel/traps.c                           |  29 +-
>   arch/mips/kernel/unaligned.c                       | 135 ++++-
>   arch/mips/lib/csum_partial.S                       | 282 +++++++----
>   arch/mips/lib/memcpy.S                             | 416 ++++++++++-----
>   arch/mips/lib/memset.S                             | 146 ++++--
>   arch/mips/lib/strlen_user.S                        |  36 +-
>   arch/mips/lib/strncpy_user.S                       |  40 +-
>   arch/mips/lib/strnlen_user.S                       |  36 +-
>   arch/mips/mm/c-r4k.c                               |  64 ++-
>   arch/mips/mm/init.c                                |  12 +-
>   arch/mips/mti-malta/malta-init.c                   |  13 +
>   arch/mips/mti-malta/malta-memory.c                 |  58 ++-
>   arch/mips/mti-malta/malta-setup.c                  |   4 +
>   35 files changed, 1974 insertions(+), 524 deletions(-)
>   create mode 100644 arch/mips/include/asm/mach-malta/spaces.h
>