[PATCH v5 3/4] resource: add walk_system_ram_res_rev()

Baoquan He
2018-06-12T03:30:11Z

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 code.

Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
---
include/linux/ioport.h | 3 +++
kernel/resource.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index b7456ae889dd..066cc263e2cc 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -279,6 +279,9 @@ extern int
walk_system_ram_res(u64 start, u64 end, void *arg,
int (*func)(struct resource *, void *));
extern int
+walk_system_ram_res_rev(u64 start, u64 end, void *arg,
+ int (*func)(struct resource *, void *));
+extern int
walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end,
void *arg, int (*func)(struct resource *, void *));

diff --git a/kernel/resource.c b/kernel/resource.c
index ef9a20b75234..3128ac938f38 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>

@@ -443,6 +445,44 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
}

/*
+ * This function, being a variant of walk_system_ram_res(), calls the @func
+ * callback against all memory ranges of type System RAM which are marked as
+ * IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY in reversed order, i.e., from
+ * higher to lower.
+ */
+int walk_system_ram_res_rev(u64 start, u64 end, void *arg,
+ int (*func)(struct resource *, void *))
+{
+ unsigned long flags;
+ struct resource *res;
+ int ret = -1;
+
+ flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+
+ read_lock(&resource_lock);
+ list_for_each_entry_reverse(res, &iomem_resource.child, sibling) {
+ if (start >= end)
+ break;
+ if ((res->flags & flags) != flags)
+ continue;
+ if (res->desc != IORES_DESC_NONE)
+ continue;
+ if (res->end < start)
+ break;
+
+ if ((res->end >= start) && (res->start < end)) {
+ ret = (*func)(res, arg);
+ if (ret)
+ break;
+ }
+ end = res->start - 1;
+
+ }
+ read_unlock(&resource_lock);
+ return ret;
+}
+
+/*
* This function calls the @func callback against all memory ranges, which
* are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
*/
--
2.13.6