powerpc, kexec_file: factor out memblock-based arch_kexec_walk_mem()

Memblock list is another source for usable system memory layout.
So move powerpc's arch_kexec_walk_mem() to common code so that other
memblock-based architectures, particularly arm64, can also utilise it.
A moved function is now renamed to kexec_walk_memblock() and integrated
into kexec_locate_mem_hole(), which will now be usable for all
architectures with no need for overriding arch_kexec_walk_mem().

With this change, arch_kexec_walk_mem() need no longer be a weak function,
and was now renamed to kexec_walk_resources().

Since powerpc doesn't support kdump in its kexec_file_load(), the current
kexec_walk_memblock() won't work for kdump either in this form, this will
be fixed in the next patch.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 57 insertions, 4 deletions

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 9e6529da12ed..d03195a8cb6e 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -16,6 +16,7 @@
 #include <linux/file.h>
 #include <linux/slab.h>
 #include <linux/kexec.h>
+#include <linux/memblock.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/fs.h>
@@ -499,8 +500,57 @@ static int locate_mem_hole_callback(struct resource *res, void *arg)
         return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
+#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
+static int kexec_walk_memblock(struct kexec_buf *kbuf,
+                               int (*func)(struct resource *, void *))
+{
+        return 0;
+}
+#else
+static int kexec_walk_memblock(struct kexec_buf *kbuf,
+                               int (*func)(struct resource *, void *))
+{
+        int ret = 0;
+        u64 i;
+        phys_addr_t mstart, mend;
+        struct resource res = { };
+
+        if (kbuf->top_down) {
+                for_each_free_mem_range_reverse(i, NUMA_NO_NODE, 0,
+                                                &mstart, &mend, NULL) {
+                        /*
+                         * In memblock, end points to the first byte after the
+                         * range while in kexec, end points to the last byte
+                         * in the range.
+                         */
+                        res.start = mstart;
+                        res.end = mend - 1;
+                        ret = func(&res, kbuf);
+                        if (ret)
+                                break;
+                }
+        } else {
+                for_each_free_mem_range(i, NUMA_NO_NODE, 0, &mstart, &mend,
+                                        NULL) {
+                        /*
+                         * In memblock, end points to the first byte after the
+                         * range while in kexec, end points to the last byte
+                         * in the range.
+                         */
+                        res.start = mstart;
+                        res.end = mend - 1;
+                        ret = func(&res, kbuf);
+                        if (ret)
+                                break;
+                }
+        }
+
+        return ret;
+}
+#endif
+
 /**
- * arch_kexec_walk_mem - call func(data) on free memory regions
+ * kexec_walk_resources - 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.
  *
@@ -508,8 +558,8 @@ static int locate_mem_hole_callback(struct resource *res, void *arg)
  * 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)(struct resource *, void *))
+static int kexec_walk_resources(struct kexec_buf *kbuf,
+                                int (*func)(struct resource *, void *))
 {
         if (kbuf->image->type == KEXEC_TYPE_CRASH)
                 return walk_iomem_res_desc(crashk_res.desc,
@@ -536,7 +586,10 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf)
         if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
                 return 0;
 
-        ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
+        if (IS_ENABLED(CONFIG_ARCH_DISCARD_MEMBLOCK))
+                ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
+        else
+                ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
 
         return ret == 1 ? 0 : -EADDRNOTAVAIL;
 }