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SubjectRe: [PATCH v2 2/9] kexec_file: Generalize kexec_add_buffer.
Date
Am Donnerstag, 16 Juni 2016, 09:58:53 schrieb Dave Young:
> On 06/15/16 at 01:21pm, Thiago Jung Bauermann wrote:
> > +/**
> > + * arch_kexec_walk_mem - call func(data) on free memory regions
> > + * @image_type: kimage.type
> > + * @top_down: Start from the highest address?
> > + * @data: Argument to pass 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(unsigned int image_type, bool top_down,
> > + void *data, int (*func)(u64, u64, void *))
> > +{
>
> top_down is also not used?

It's unused in the default implementation, but the powerpc implementation in patch 8 uses it:

int arch_kexec_walk_mem(unsigned int type, bool top_down, void *data,
int (*func)(u64, u64, void *))
{
int ret = 0;
u64 i;
phys_addr_t mstart, mend;

if (top_down) {
for_each_free_mem_range_reverse(i, NUMA_NO_NODE, 0,
&mstart, &mend, NULL) {
ret = func(mstart, mend, data);
if (ret)
break;
}
} else {
for_each_free_mem_range(i, NUMA_NO_NODE, 0, &mstart, &mend,
NULL) {
ret = func(mstart, mend, data);
if (ret)
break;
}
}

return ret;
}

> Rethink about the argument name type should be better than image_type,
> it is obvious in the comments and the code and simpler.

Ok, renamed in the patch below.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


kexec_file: Generalize kexec_add_buffer.

Allow architectures to specify different memory walking functions for
kexec_add_buffer. Intel 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>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e8acb2b43dd9..42b31f2e1d88 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -315,6 +315,8 @@ int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
Elf_Shdr *sechdrs, unsigned int relsec);
int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec);
+int __weak arch_kexec_walk_mem(unsigned int type, bool top_down, void *data,
+ int (*func)(u64, u64, void *));
void arch_kexec_protect_crashkres(void);
void arch_kexec_unprotect_crashkres(void);

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b6eec7527e9f..989647a324f2 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -428,6 +428,29 @@ 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
+ * @type: kimage.type
+ * @top_down: Start from the highest address?
+ * @data: Argument to pass 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(unsigned int type, bool top_down, void *data,
+ int (*func)(u64, u64, void *))
+{
+ if (type == KEXEC_TYPE_CRASH)
+ return walk_iomem_res_desc(crashk_res.desc,
+ IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+ crashk_res.start, crashk_res.end,
+ data, func);
+ else
+ return walk_system_ram_res(0, ULONG_MAX, data, func);
+}
+
/*
* Helper function for placing a buffer in a kexec segment. This assumes
* that kexec_mutex is held.
@@ -472,14 +495,8 @@ 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(image->type, top_down, kbuf,
+ locate_mem_hole_callback);
if (ret != 1) {
/* A suitable memory range could not be found for buffer */
return -EADDRNOTAVAIL;
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