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Subject[PATCH v3 02/10] resource: add walk_system_ram_res_rev()
Date
This function, being a variant of walk_system_ram_res() introduced in
commit 8c86e70acead ("resource: provide new functions to walk through
resources"), walks through a list of all the resources of System RAM
in reversed order, i.e., from higher to lower.

It will be used in kexec_file implementation on arm64.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/ioport.h | 3 +++
kernel/resource.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 62 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6230064d7f95..9a212266299f 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -271,6 +271,9 @@ extern int
walk_system_ram_res(u64 start, u64 end, void *arg,
int (*func)(u64, u64, void *));
extern int
+walk_system_ram_res_rev(u64 start, u64 end, void *arg,
+ int (*func)(u64, u64, void *));
+extern int
walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end,
void *arg, int (*func)(u64, u64, void *));

diff --git a/kernel/resource.c b/kernel/resource.c
index 9b5f04404152..572f2f91ce9c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -23,6 +23,8 @@
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/resource_ext.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
#include <asm/io.h>


@@ -469,6 +471,63 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
return ret;
}

+int walk_system_ram_res_rev(u64 start, u64 end, void *arg,
+ int (*func)(u64, u64, void *))
+{
+ struct resource res, *rams;
+ u64 orig_end;
+ int count, i;
+ int ret = -1;
+
+ count = 16; /* initial */
+
+ /* create a list */
+ rams = vmalloc(sizeof(struct resource) * count);
+ if (!rams)
+ return ret;
+
+ res.start = start;
+ res.end = end;
+ res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+ orig_end = res.end;
+ i = 0;
+ while ((res.start < res.end) &&
+ (!find_next_iomem_res(&res, IORES_DESC_NONE, true))) {
+ if (i >= count) {
+ /* re-alloc */
+ struct resource *rams_new;
+ int count_new;
+
+ count_new = count + 16;
+ rams_new = vmalloc(sizeof(struct resource) * count_new);
+ if (!rams_new)
+ goto out;
+
+ memcpy(rams_new, rams, count);
+ vfree(rams);
+ rams = rams_new;
+ count = count_new;
+ }
+
+ rams[i].start = res.start;
+ rams[i++].end = res.end;
+
+ res.start = res.end + 1;
+ res.end = orig_end;
+ }
+
+ /* go reverse */
+ for (i--; i >= 0; i--) {
+ ret = (*func)(rams[i].start, rams[i].end, arg);
+ if (ret)
+ break;
+ }
+
+out:
+ vfree(rams);
+ return ret;
+}
+
#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)

/*
--
2.14.1
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