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Message-ID: <20160629194751.GB5488@dhcp-128-65.nay.redhat.com>
Date: Wed, 29 Jun 2016 15:47:51 -0400
From: Dave Young <dyoung@...hat.com>
To: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
Cc: kexec@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org,
Eric Biederman <ebiederm@...ssion.com>
Subject: Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.
On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 23 Juni 2016, 10:25:06 schrieb Dave Young:
> > On 06/22/16 at 08:30pm, Thiago Jung Bauermann wrote:
> > > Am Mittwoch, 22 Juni 2016, 18:20:47 schrieb Dave Young:
> > > > The patch looks good, but could the subject be more specific?
> > > >
> > > > For example just like the first sentence of the patch descriotion:
> > > > Allow architectures to specify their own memory walking function
> > >
> > > Ok, What about this? I also changed the description to refer to x86 arch
> > > instead of Intel arch.
> >
> > It looks good to me.
>
> This version has the struct kexec_buf documentation comments that were
> in patch 3/9. I fixed the names of the struct members, and changed their
> descriptions to try to be clearer.
> --
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
>
>
> Subject: [PATCH 2/9] kexec_file: Allow arch-specific memory walking for
> kexec_add_buffer
>
> 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@...ux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@...ssion.com>
> Cc: Dave Young <dyoung@...hat.com>
> Cc: kexec@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
> include/linux/kexec.h | 25 ++++++++++++++++++++++++-
> kernel/kexec_file.c | 30 ++++++++++++++++++++++--------
> kernel/kexec_internal.h | 14 --------------
> 3 files changed, 46 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..e16d845d587f 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,30 @@ 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.
> + * @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;
> + unsigned long mem;
> + unsigned long memsz;
> + unsigned long buf_align;
> + unsigned long buf_min;
> + unsigned long buf_max;
> + bool top_down;
> +};
Rethink about the first patch, you dropped the user buffer in kexec_buf
But later your passing IMA digests buffer patchset may need use it.
So keep it in kexec_buf should be better.
For the IMA buffer patchset I'm still reading and learning the
background, will reply them later.
> +
> +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 b6eec7527e9f..b1f1f6402518 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.
> @@ -472,14 +493,7 @@ 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 eefd5bf960c2..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,20 +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;
> - 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
>
>
Thanks
Dave
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