Re: [PATCH 2/7] exec: Split out variable page size support to exec-vary.c

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 9/20/19 1:29 AM, Richard Henderson wrote:
> The next patch will play a trick with "const" that will
> confuse the compiler about the uses of target_page_bits
> within exec.c.  Moving everything to a new file prevents
> this confusion.
> 
> No functional change so far.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  Makefile.target       |  2 +-
>  include/qemu-common.h |  6 +++++
>  exec-vary.c           | 57 +++++++++++++++++++++++++++++++++++++++++++
>  exec.c                | 34 --------------------------
>  4 files changed, 64 insertions(+), 35 deletions(-)
>  create mode 100644 exec-vary.c
> 
> diff --git a/Makefile.target b/Makefile.target
> index 5e916230c4..ca3d14efe1 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -107,7 +107,7 @@ obj-y += trace/
>  
>  #########################################################
>  # cpu emulator library
> -obj-y += exec.o
> +obj-y += exec.o exec-vary.o
>  obj-y += accel/
>  obj-$(CONFIG_TCG) += tcg/tcg.o tcg/tcg-op.o tcg/tcg-op-vec.o tcg/tcg-op-gvec.o
>  obj-$(CONFIG_TCG) += tcg/tcg-common.o tcg/optimize.o
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index 0235cd3b91..3e800c2224 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -74,6 +74,12 @@ void cpu_exec_step_atomic(CPUState *cpu);
>   */
>  bool set_preferred_target_page_bits(int bits);
>  
> +/**
> + * finalize_target_page_bits:
> + * Commit the final value set by set_preferred_target_page_bits.
> + */
> +void finalize_target_page_bits(void);
> +
>  /**
>   * Sends a (part of) iovec down a socket, yielding when the socket is full, or
>   * Receives data into a (part of) iovec from a socket,
> diff --git a/exec-vary.c b/exec-vary.c
> new file mode 100644
> index 0000000000..48c0ab306c
> --- /dev/null
> +++ b/exec-vary.c
> @@ -0,0 +1,57 @@
> +/*
> + * Variable page size handling
> + *
> + *  Copyright (c) 2003 Fabrice Bellard
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +#include "exec/exec-all.h"
> +
> +#ifdef TARGET_PAGE_BITS_VARY
> +int target_page_bits;
> +bool target_page_bits_decided;
> +#endif
> +
> +bool set_preferred_target_page_bits(int bits)
> +{
> +    /*
> +     * The target page size is the lowest common denominator for all
> +     * the CPUs in the system, so we can only make it smaller, never
> +     * larger. And we can't make it smaller once we've committed to
> +     * a particular size.
> +     */
> +#ifdef TARGET_PAGE_BITS_VARY
> +    assert(bits >= TARGET_PAGE_BITS_MIN);
> +    if (target_page_bits == 0 || target_page_bits > bits) {
> +        if (target_page_bits_decided) {
> +            return false;
> +        }
> +        target_page_bits = bits;
> +    }
> +#endif
> +    return true;
> +}
> +
> +void finalize_target_page_bits(void)
> +{
> +#ifdef TARGET_PAGE_BITS_VARY
> +    if (target_page_bits == 0) {
> +        target_page_bits = TARGET_PAGE_BITS_MIN;
> +    }
> +    target_page_bits_decided = true;
> +#endif
> +}
> diff --git a/exec.c b/exec.c
> index 8b998974f8..33bd0e36c1 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -92,11 +92,6 @@ MemoryRegion io_mem_rom, io_mem_notdirty;
>  static MemoryRegion io_mem_unassigned;
>  #endif
>  
> -#ifdef TARGET_PAGE_BITS_VARY
> -int target_page_bits;
> -bool target_page_bits_decided;
> -#endif
> -
>  CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus);
>  
>  /* current CPU in the current thread. It is only valid inside
> @@ -110,37 +105,8 @@ int use_icount;
>  uintptr_t qemu_host_page_size;
>  intptr_t qemu_host_page_mask;
>  
> -bool set_preferred_target_page_bits(int bits)
> -{
> -    /* The target page size is the lowest common denominator for all
> -     * the CPUs in the system, so we can only make it smaller, never
> -     * larger. And we can't make it smaller once we've committed to
> -     * a particular size.
> -     */
> -#ifdef TARGET_PAGE_BITS_VARY
> -    assert(bits >= TARGET_PAGE_BITS_MIN);
> -    if (target_page_bits == 0 || target_page_bits > bits) {
> -        if (target_page_bits_decided) {
> -            return false;
> -        }
> -        target_page_bits = bits;
> -    }
> -#endif
> -    return true;
> -}
> -
>  #if !defined(CONFIG_USER_ONLY)
>  
> -static void finalize_target_page_bits(void)
> -{
> -#ifdef TARGET_PAGE_BITS_VARY
> -    if (target_page_bits == 0) {
> -        target_page_bits = TARGET_PAGE_BITS_MIN;
> -    }
> -    target_page_bits_decided = true;
> -#endif
> -}
> -
>  typedef struct PhysPageEntry PhysPageEntry;
>  
>  struct PhysPageEntry {
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>