On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauer...@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebied...@xmission.com>
> Cc: Dave Young <dyo...@redhat.com>
> Cc: ke...@lists.infradead.org
> Cc: linux-ker...@vger.kernel.org
> ---
>  include/linux/kexec.h |  4 ++++
>  kernel/kexec_file.c   | 66 
> ++++++++++++++++++++++++++++++++++++++-------------
>  2 files changed, 53 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..4ca6f5f95d66 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -227,6 +227,10 @@ extern asmlinkage long sys_kexec_load(unsigned long 
> entry,
>                                       struct kexec_segment __user *segments,
>                                       unsigned long flags);
>  extern int kernel_kexec(void);
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +                       unsigned long align, unsigned long min_addr,
> +                       unsigned long max_addr, bool top_down,
> +                       unsigned long *addr);
>  extern int kexec_add_buffer(struct kimage *image, char *buffer,
>                           unsigned long bufsz, unsigned long memsz,
>                           unsigned long buf_align, unsigned long buf_min,
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..85a515511925 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,46 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>               return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in 
> purgatory
> + * @image:   kexec image being updated.
> + * @size:    Memory size.
> + * @align:   Minimum alignment needed.
> + * @min_addr:        Minimum starting address.
> + * @max_addr:        Maximum end address.
> + * @top_down Find the highest free memory region?
> + * @addr     On success, will have start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +                       unsigned long align, unsigned long min_addr,
> +                       unsigned long max_addr, bool top_down,
> +                       unsigned long *addr)
> +{
> +     int ret;
> +     struct kexec_buf buf;
> +
> +     memset(&buf, 0, sizeof(struct kexec_buf));
> +     buf.image = image;
> +
> +     buf.memsz = size;
> +     buf.buf_align = align;
> +     buf.buf_min = min_addr;
> +     buf.buf_max = max_addr;
> +     buf.top_down = top_down;

Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
will be natural to passing a kexec_buf pointer intead of passing all
these arguments in kexec_locate_mem_hole.

kbuf.mem can be used for addr.

> +
> +     ret = arch_kexec_walk_mem(&buf, locate_mem_hole_callback);
> +     if (ret != 1) {
> +             /* A suitable memory range could not be found for buffer */
> +             return -EADDRNOTAVAIL;
> +     }
> +
> +     *addr = buf.mem;
> +
> +     return 0;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -460,8 +500,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, 
> unsigned long bufsz,
>  {
>  
>       struct kexec_segment *ksegment;
> -     struct kexec_buf buf, *kbuf;
>       int ret;
> +     unsigned long addr, align, size;
>  
>       /* Currently adding segment this way is allowed only in file mode */
>       if (!image->file_mode)
> @@ -482,29 +522,21 @@ int kexec_add_buffer(struct kimage *image, char 
> *buffer, unsigned long bufsz,
>               return -EINVAL;
>       }
>  
> -     memset(&buf, 0, sizeof(struct kexec_buf));
> -     kbuf = &buf;
> -     kbuf->image = image;
> -
> -     kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
> -     kbuf->buf_align = max(buf_align, PAGE_SIZE);
> -     kbuf->buf_min = buf_min;
> -     kbuf->buf_max = buf_max;
> -     kbuf->top_down = top_down;
> +     size = ALIGN(memsz, PAGE_SIZE);
> +     align = max(buf_align, PAGE_SIZE);
>  
>       /* Walk the RAM ranges and allocate a suitable range for the buffer */
> -     ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -     if (ret != 1) {
> -             /* A suitable memory range could not be found for buffer */
> -             return -EADDRNOTAVAIL;
> -     }
> +     ret = kexec_locate_mem_hole(image, size, align, buf_min, buf_max,
> +                                 top_down, &addr);
> +     if (ret)
> +             return ret;
>  
>       /* Found a suitable memory range */
>       ksegment = &image->segment[image->nr_segments];
>       ksegment->kbuf = buffer;
>       ksegment->bufsz = bufsz;
> -     ksegment->mem = kbuf->mem;
> -     ksegment->memsz = kbuf->memsz;
> +     ksegment->mem = addr;
> +     ksegment->memsz = size;
>       image->nr_segments++;
>       *load_addr = ksegment->mem;
>       return 0;

Thanks
Dave
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