Re: [GIT PULL] RISC-V Cleanups and ABI Fixes for 4.15-rc2

[Andrea Parri <parri.andrea@gmail.com>]

Hi Palmer,

On Fri, Dec 01, 2017 at 01:39:12PM -0800, Palmer Dabbelt wrote:
> The following changes since commit 4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323:
> 
>   Linux 4.15-rc1 (2017-11-26 16:01:47 -0800)
> 
> are available in the git repository at:
> 
>   ssh://git@gitolite.kernel.org/pub/scm/linux/kernel/git/palmer/linux.git tags/riscv-for-linus-4.15-rc2_cleanups
> 
> for you to fetch changes up to 3b62de26cf5ef17340a0e986d3e53eb4f74f96d5:
> 
>   RISC-V: Fixes for clean allmodconfig build (2017-12-01 13:31:31 -0800)
> 
> ----------------------------------------------------------------
> RISC-V Cleanups and ABI Fixes for 4.15-rc2
> 
> This tag contains a handful of small cleanups that are a result of
> feedback that didn't make it into our original patch set, either because
> the feedback hadn't been given yet, I missed the original emails, or
> we weren't ready to submit the changes yet.
> 
> I've been maintaining the various cleanup patch sets I have as their own
> branches, which I then merged together and signed.  Each merge commit
> has a short summary of the changes, and each branch is based on your
> latest tag (4.15-rc1, in this case).  If this isn't the right way to do
> this then feel free to suggest something else, but it seems sane to me.
> 
> Here's a short summary of the changes, roughly in order of how
> interesting they are.
> 
> * libgcc.h has been moved from include/lib, where it's the only member,
>   to include/linux.  This is meant to avoid tab completion conflicts.
> * VDSO entries for clock_get/gettimeofday/getcpu have been added.  These
>   are simple syscalls now, but we want to let glibc use them from the
>   start so we can make them faster later.
> * A VDSO entry for instruction cache flushing has been added so
>   userspace can flush the instruction cache.
> * The VDSO symbol versions for __vdso_cmpxchg{32,64} have been removed,
>   as those VDSO entries don't actually exist.
> * __io_writes has been corrected to respect the given type.
> * A new READ_ONCE in arch_spin_is_locked().
> * __test_and_op_bit_ord() is now actually ordered.
> * Various small fixes throughout the tree to enable allmodconfig to
>   build cleanly.
> * Removal of some dead code in our atomic support headers.
> * Improvements to various comments in our atomic support headers.
> 
> ----------------------------------------------------------------
> Andrew Waterman (3):
>       RISC-V: Add VDSO entries for clock_get/gettimeofday/getcpu
>       RISC-V: Flush I$ when making a dirty page executable
>       RISC-V: Allow userspace to flush the instruction cache
> 
> Christoph Hellwig (1):
>       move libgcc.h to include/linux
> 
> Olof Johansson (8):
>       RISC-V: use generic serial.h
>       RISC-V: use RISCV_{INT,SHORT} instead of {INT,SHORT} for asm macros
>       RISC-V: io.h: type fixes for warnings
>       RISC-V: move empty_zero_page definition to C and export it
>       RISC-V: Export some expected symbols for modules
>       RISC-V: Provide stub of setup_profiling_timer()
>       RISC-V: Use define for get_cycles like other architectures
>       RISC-V: Add missing include
> 
> Palmer Dabbelt (16):
>       RISC-V: Remove __vdso_cmpxchg{32,64} symbol versions
>       RISC-V: Remove unused arguments from ATOMIC_OP
>       RISC-V: Comment on why {,cmp}xchg is ordered how it is
>       RISC-V: Remove __smp_bp__{before,after}_atomic
>       RISC-V: Remove smb_mb__{before,after}_spinlock()

I wonder whether you really meant to remove smp_mb__after_spinlock():
on the one hand, this primitive doesn't seem "obsolete" (as suggested
by the commit message); on the other hand, the Draft Specification at

  https://marc.info/?l=linux-kernel&m=151218405830993&w=2

suggests that you need "to strengthen" the generic implementation for
this primitive (considered the current spinlock.h in riscv).  What am
I missing?

  Andrea


>       RISC-V: __test_and_op_bit_ord should be strongly ordered
>       RISC-V: Add READ_ONCE in arch_spin_is_locked()
>       RISC-V: `sfence.vma` orderes the instruction cache
>       RISC-V: remove spin_unlock_wait()
>       RISC-V: Clean up an unused include
>       RISC-V: __io_writes should respect the length argument
>       RISC-V Atomic Cleanups
>       RISC-V: User-Visible Changes
>       RISC-V: __io_writes should respect the length argument
>       move libgcc.h to include/linux
>       RISC-V: Fixes for clean allmodconfig build
> 
>  arch/riscv/include/asm/Kbuild          |   1 +
>  arch/riscv/include/asm/asm.h           |  12 ++--
>  arch/riscv/include/asm/atomic.h        | 103 +++++++++++++++++----------------
>  arch/riscv/include/asm/barrier.h       |  23 --------
>  arch/riscv/include/asm/bitops.h        |   2 +-
>  arch/riscv/include/asm/bug.h           |   6 +-
>  arch/riscv/include/asm/cacheflush.h    |  30 ++++++++--
>  arch/riscv/include/asm/io.h            |  18 +++---
>  arch/riscv/include/asm/mmu.h           |   4 ++
>  arch/riscv/include/asm/mmu_context.h   |  45 ++++++++++++++
>  arch/riscv/include/asm/pgtable.h       |  58 ++++++++++---------
>  arch/riscv/include/asm/spinlock.h      |  11 +---
>  arch/riscv/include/asm/timex.h         |   3 +-
>  arch/riscv/include/asm/tlbflush.h      |   7 ++-
>  arch/riscv/include/asm/vdso-syscalls.h |  28 +++++++++
>  arch/riscv/include/asm/vdso.h          |   4 ++
>  arch/riscv/kernel/head.S               |   3 -
>  arch/riscv/kernel/riscv_ksyms.c        |   3 +
>  arch/riscv/kernel/setup.c              |   5 ++
>  arch/riscv/kernel/smp.c                |  55 ++++++++++++++++++
>  arch/riscv/kernel/sys_riscv.c          |  33 ++++++++++-
>  arch/riscv/kernel/syscall_table.c      |   2 +
>  arch/riscv/kernel/vdso/Makefile        |   7 ++-
>  arch/riscv/kernel/vdso/clock_getres.S  |  26 +++++++++
>  arch/riscv/kernel/vdso/clock_gettime.S |  26 +++++++++
>  arch/riscv/kernel/vdso/flush_icache.S  |  31 ++++++++++
>  arch/riscv/kernel/vdso/getcpu.S        |  26 +++++++++
>  arch/riscv/kernel/vdso/gettimeofday.S  |  26 +++++++++
>  arch/riscv/kernel/vdso/vdso.lds.S      |   7 ++-
>  arch/riscv/lib/delay.c                 |   1 +
>  arch/riscv/mm/Makefile                 |   1 +
>  arch/riscv/mm/cacheflush.c             |  23 ++++++++
>  arch/riscv/mm/ioremap.c                |   2 +-
>  include/{lib => linux}/libgcc.h        |   0
>  lib/ashldi3.c                          |   2 +-
>  lib/ashrdi3.c                          |   2 +-
>  lib/cmpdi2.c                           |   2 +-
>  lib/lshrdi3.c                          |   2 +-
>  lib/muldi3.c                           |   2 +-
>  lib/ucmpdi2.c                          |   2 +-
>  40 files changed, 498 insertions(+), 146 deletions(-)
>  create mode 100644 arch/riscv/include/asm/vdso-syscalls.h
>  create mode 100644 arch/riscv/kernel/vdso/clock_getres.S
>  create mode 100644 arch/riscv/kernel/vdso/clock_gettime.S
>  create mode 100644 arch/riscv/kernel/vdso/flush_icache.S
>  create mode 100644 arch/riscv/kernel/vdso/getcpu.S
>  create mode 100644 arch/riscv/kernel/vdso/gettimeofday.S
>  create mode 100644 arch/riscv/mm/cacheflush.c
>  rename include/{lib => linux}/libgcc.h (100%)