Re: [PATCH v4 1/9] kexec_file: Allow arch-specific memory walking for kexec_add_buffer

Dave Young
2016-07-11T03:21:25Z

On 07/07/16 at 01:23pm, Thiago Jung Bauermann wrote:
> Allow architectures to specify a different memory walking function for
> kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
> PowerPC uses the memblock subsystem.
>
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> ---
> include/linux/kexec.h | 29 ++++++++++++++++++++++++++++-
> kernel/kexec_file.c | 30 ++++++++++++++++++++++--------
> kernel/kexec_internal.h | 16 ----------------
> 3 files changed, 50 insertions(+), 25 deletions(-)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..2549a99a748c 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,34 @@ struct kexec_file_ops {
> kexec_verify_sig_t *verify_sig;
> #endif
> };
> -#endif
> +
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image: kexec image in which memory to search.
> + * @buffer: Contents which will be copied to the allocated memory.
> + * @bufsz: Size of @buffer.
> + * @mem: On return will have address of the buffer in memory.
> + * @memsz: Size for the buffer in memory.
> + * @buf_align: Minimum alignment needed.
> + * @buf_min: The buffer can't be placed below this address.
> + * @buf_max: The buffer can't be placed above this address.
> + * @top_down: Allocate from top of memory.
> + */
> +struct kexec_buf {
> + struct kimage *image;
> + char *buffer;
> + unsigned long bufsz;
> + unsigned long mem;
> + unsigned long memsz;
> + unsigned long buf_align;
> + unsigned long buf_min;
> + unsigned long buf_max;
> + bool top_down;
> +};
> +
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> + int (*func)(u64, u64, void *));
> +#endif /* CONFIG_KEXEC_FILE */
>
> struct kimage {
> kimage_entry_t head;
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 01ab82a40d22..9c0c565a08db 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
> return locate_mem_hole_bottom_up(start, end, kbuf);
> }
>
> +/**
> + * arch_kexec_walk_mem - call func(data) on free memory regions
> + * @kbuf: Context info for the search. Also passed to @func.
> + * @func: Function to call for each memory region.
> + *
> + * Return: The memory walk will stop when func returns a non-zero value
> + * and that value will be returned. If all free regions are visited without
> + * func returning non-zero, then zero will be returned.
> + */
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> + int (*func)(u64, u64, void *))
> +{
> + if (kbuf->image->type == KEXEC_TYPE_CRASH)
> + return walk_iomem_res_desc(crashk_res.desc,
> + IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> + crashk_res.start, crashk_res.end,
> + kbuf, func);
> + else
> + return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> +}
> +
> /*
> * Helper function for placing a buffer in a kexec segment. This assumes
> * that kexec_mutex is held.
> @@ -474,14 +495,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
> kbuf->top_down = top_down;
>
> /* Walk the RAM ranges and allocate a suitable range for the buffer */
> - if (image->type == KEXEC_TYPE_CRASH)
> - ret = walk_iomem_res_desc(crashk_res.desc,
> - IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> - crashk_res.start, crashk_res.end, kbuf,
> - locate_mem_hole_callback);
> - else
> - ret = walk_system_ram_res(0, -1, kbuf,
> - locate_mem_hole_callback);
> + 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;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index 0a52315d9c62..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,22 +20,6 @@ struct kexec_sha_region {
> unsigned long len;
> };
>
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> - */
> -struct kexec_buf {
> - struct kimage *image;
> - char *buffer;
> - unsigned long bufsz;
> - unsigned long mem;
> - unsigned long memsz;
> - unsigned long buf_align;
> - unsigned long buf_min;
> - unsigned long buf_max;
> - bool top_down; /* allocate from top of memory hole */
> -};
> -
> void kimage_file_post_load_cleanup(struct kimage *image);
> #else /* CONFIG_KEXEC_FILE */
> static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
> --
> 1.9.1
>

Acked-by: Dave Young <dyoung@redhat.com>

Thanks
Dave