We pass the following properties to crash dump kernel:
/chosen/linux,elfcorehdr: elf core header segment,
                                same as "elfcorehdr=" as on other archs
/reserved-memory/crash_dump@xx: any memory regions to be dumped
                                into /proc/vmcore

Then, we are ready to support kdump.

Signed-off-by: AKASHI Takahiro <[email protected]>
---
 kexec/arch/arm64/crashdump-arm64.c | 141 ++++++++++++++++++++++++++++++++++++-
 kexec/arch/arm64/crashdump-arm64.h |   2 +
 kexec/arch/arm64/kexec-arm64.c     |  34 +++++++--
 kexec/arch/arm64/kexec-elf-arm64.c |   5 --
 4 files changed, 171 insertions(+), 11 deletions(-)

diff --git a/kexec/arch/arm64/crashdump-arm64.c 
b/kexec/arch/arm64/crashdump-arm64.c
index 9517329..01b9716 100644
--- a/kexec/arch/arm64/crashdump-arm64.c
+++ b/kexec/arch/arm64/crashdump-arm64.c
@@ -13,6 +13,7 @@
 #define _GNU_SOURCE
 
 #include <errno.h>
+#include <stdlib.h>
 #include <linux/elf.h>
 
 #include "kexec.h"
@@ -21,11 +22,12 @@
 #include "iomem.h"
 #include "kexec-arm64.h"
 #include "kexec-elf.h"
+#include "libfdt.h"
 #include "mem_regions.h"
 
 /* memory ranges on crashed kernel */
 static struct memory_range crash_memory_ranges[CRASH_MAX_MEMORY_RANGES];
-static struct memory_ranges crash_memory_rgns = {
+struct memory_ranges crash_memory_rgns = {
        .size = 0,
        .max_size = CRASH_MAX_MEMORY_RANGES,
        .ranges = crash_memory_ranges,
@@ -236,3 +238,140 @@ void modify_ehdr_for_crashdump(struct mem_ehdr *ehdr)
                        (-arm64_mem.phys_offset + crash_reserved_mem.start);
        }
 }
+
+static int dtb_add_reserved_memory(void *dtb_buf)
+{
+       int nodeoffset, rsvmem_node;
+       uint32_t cell_size;
+       uint64_t range[2];
+       char name[30];
+       int i, result = 0;
+
+       rsvmem_node = fdt_path_offset(dtb_buf, "reserved-memory");
+       if (rsvmem_node < 0) {
+               nodeoffset = fdt_path_offset(dtb_buf, "/");
+               rsvmem_node = fdt_add_subnode(dtb_buf, nodeoffset,
+                                               "reserved-memory");
+               if (rsvmem_node < 0) {
+                       result = rsvmem_node;
+                       goto on_error;
+               }
+
+               cell_size = cpu_to_fdt32(2);
+               fdt_setprop(dtb_buf, rsvmem_node, "#address-cells",
+                                               &cell_size, sizeof(cell_size));
+               fdt_setprop(dtb_buf, rsvmem_node, "#size-cells",
+                                               &cell_size, sizeof(cell_size));
+               fdt_setprop(dtb_buf, rsvmem_node, "ranges", NULL, 0);
+       }
+
+       for (i = 0; i < crash_memory_rgns.size; i++) {
+               sprintf(name, "crash_dump@%llx",
+                                       crash_memory_rgns.ranges[i].start);
+               nodeoffset = fdt_add_subnode(dtb_buf, rsvmem_node, name);
+               if (nodeoffset < 0) {
+                       result = nodeoffset;
+                       goto on_error;
+               }
+
+               range[0] = cpu_to_fdt64(crash_memory_rgns.ranges[i].start);
+               range[1] = cpu_to_fdt64(crash_memory_rgns.ranges[i].end
+                                       - crash_memory_rgns.ranges[i].start + 
1);
+               fdt_setprop(dtb_buf, nodeoffset, "reg", &range, sizeof(range));
+               fdt_setprop(dtb_buf, nodeoffset, "no-map", NULL, 0);
+       }
+
+on_error:
+       return result;
+}
+
+/*
+ * Increased size for extra properties:
+ * - linux,elfcorehdr
+ *      linux,elfcoredhr = <base, size>;
+ * - reserved-memory node
+ *      reserved-memory {
+ *         #address-cells = <2>;
+ *         #size-cells = <2>;
+ *         ranges;
+ *         crash_dump@xx {
+ *            reg = <base, size>;
+ *            no-map;
+ *         };
+ *         ...
+ *      }
+ */
+#define DTB_ELFCOREHDR_PROP_SIZE \
+                (sizeof(struct fdt_property)           \
+               + FDT_TAGALIGN(sizeof(uint64_t) * 2)    \
+               + strlen("linux,elfcorehdr") + 1)
+#define DTB_RESVMEM_NODE_SIZE \
+                (sizeof(struct fdt_node_header)        \
+               + strlen("reserved-memory") + 1         \
+               + sizeof(struct fdt_property)           \
+               + FDT_TAGALIGN(sizeof(uint32_t))        \
+               + strlen("#address-cells") + 1          \
+               + sizeof(struct fdt_property)           \
+               + FDT_TAGALIGN(sizeof(uint32_t))        \
+               + strlen("#size-cells") + 1             \
+               + sizeof(struct fdt_property)           \
+               + strlen("ranges") + 1)
+#define DTB_RESVMEM_SUBNODE_SIZE \
+                (sizeof(struct fdt_node_header)        \
+               + strlen("crash_dump@xxxxxxxxxxxxxxxx") + 1     \
+               + sizeof(struct fdt_property)           \
+               + FDT_TAGALIGN(sizeof(uint64_t) * 2)    \
+               + strlen("reg") + 1                     \
+               + sizeof(struct fdt_property)   \
+               + strlen("no-map") + 1)
+
+void *fixup_memory_properties(void *dtb_buf)
+{
+       char *new_buf;
+       int new_size;
+       uint64_t range[2];
+       int nodeoffset;
+       int result;
+
+       new_size = fdt_totalsize(dtb_buf)
+                  + DTB_ELFCOREHDR_PROP_SIZE
+                  + DTB_RESVMEM_NODE_SIZE
+                  + DTB_RESVMEM_SUBNODE_SIZE * crash_memory_rgns.size;
+
+       new_buf = xmalloc(new_size);
+       result = fdt_open_into(dtb_buf, new_buf, new_size);
+       if (result) {
+               dbgprintf("%s: fdt_open_into failed: %s\n", __func__,
+                                               fdt_strerror(result));
+               result = -EFAILED;
+               goto on_error;
+       }
+
+       range[0] = cpu_to_fdt64(elfcorehdr_mem.start);
+       range[1] = cpu_to_fdt64(elfcorehdr_mem.end - elfcorehdr_mem.start + 1);
+       nodeoffset = fdt_path_offset(new_buf, "/chosen");
+       result = fdt_setprop(new_buf, nodeoffset, "linux,elfcorehdr",
+                                               (void *)range, sizeof(range));
+       if (result) {
+               dbgprintf("%s: fdt_setprop failed: %s\n", __func__,
+                                               fdt_strerror(result));
+               goto on_error;
+       }
+
+       result = dtb_add_reserved_memory(new_buf);
+       if (result) {
+               dbgprintf("%s: adding reserved-memory failed: %s\n", __func__,
+                                               fdt_strerror(result));
+               result = -EFAILED;
+               goto on_error;
+       }
+
+       fdt_pack(new_buf);
+
+       return new_buf;
+
+on_error:
+       if (new_buf)
+               free(new_buf);
+       return NULL;
+}
diff --git a/kexec/arch/arm64/crashdump-arm64.h 
b/kexec/arch/arm64/crashdump-arm64.h
index 382f571..25889bc 100644
--- a/kexec/arch/arm64/crashdump-arm64.h
+++ b/kexec/arch/arm64/crashdump-arm64.h
@@ -16,11 +16,13 @@
 
 #define CRASH_MAX_MEMORY_RANGES        32
 
+extern struct memory_ranges crash_memory_rgns;
 extern struct memory_ranges usablemem_rgns;
 extern struct memory_range crash_reserved_mem;
 extern struct memory_range elfcorehdr_mem;
 
 extern int load_crashdump_segments(struct kexec_info *info);
 extern void modify_ehdr_for_crashdump(struct mem_ehdr *ehdr);
+extern void *fixup_memory_properties(void *dtb_buf);
 
 #endif /* CRASHDUMP_ARM64_H */
diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index bcb4e76..6f26f29 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -128,9 +128,6 @@ int arch_process_options(int argc, char **argv)
                case OPT_INITRD:
                        arm64_opts.initrd = optarg;
                        break;
-               case OPT_PANIC:
-                       die("load-panic (-p) not supported");
-                       break;
                default:
                        break; /* Ignore core and unknown options. */
                }
@@ -283,8 +280,10 @@ on_success:
  * setup_2nd_dtb - Setup the 2nd stage kernel's dtb.
  */
 
-static int setup_2nd_dtb(struct dtb *dtb, char *command_line)
+static int setup_2nd_dtb(struct dtb *dtb, char *command_line, int on_crash)
 {
+       int nodeoffset;
+       void *new_buf;
        int result;
 
        result = fdt_check_header(dtb->buf);
@@ -296,8 +295,32 @@ static int setup_2nd_dtb(struct dtb *dtb, char 
*command_line)
 
        result = set_bootargs(dtb, command_line);
 
+       /*
+        * Those properties are meaningful only for the current kernel.
+        * So remove them anyway.
+        */
+       nodeoffset = fdt_path_offset(dtb->buf, "/chosen");
+       fdt_delprop(dtb->buf, nodeoffset, "linux,crashkernel-base");
+       fdt_delprop(dtb->buf, nodeoffset, "linux,crashkernel-size");
+       fdt_delprop(dtb->buf, nodeoffset, "linux,elfcorehdr");
+
+       if (on_crash) {
+               new_buf = fixup_memory_properties(dtb->buf);
+               if (!new_buf)
+                       goto on_error;
+
+               dtb->buf = new_buf;
+               dtb->size = fdt_totalsize(new_buf);
+       }
+
        dump_reservemap(dtb);
 
+
+       return result;
+
+on_error:
+       fprintf(stderr, "kexec: %s failed.\n", __func__);
+
        return result;
 }
 
@@ -365,7 +388,8 @@ int arm64_load_other_segments(struct kexec_info *info,
                }
        }
 
-       result = setup_2nd_dtb(&dtb, command_line);
+       result = setup_2nd_dtb(&dtb, command_line,
+                       info->kexec_flags & KEXEC_ON_CRASH);
 
        if (result)
                return -EFAILED;
diff --git a/kexec/arch/arm64/kexec-elf-arm64.c 
b/kexec/arch/arm64/kexec-elf-arm64.c
index 842ce21..b17a31a 100644
--- a/kexec/arch/arm64/kexec-elf-arm64.c
+++ b/kexec/arch/arm64/kexec-elf-arm64.c
@@ -47,11 +47,6 @@ int elf_arm64_load(int argc, char **argv, const char 
*kernel_buf,
        int result;
        int i;
 
-       if (info->kexec_flags & KEXEC_ON_CRASH) {
-               fprintf(stderr, "kexec: kdump not yet supported on arm64\n");
-               return -EFAILED;
-       }
-
        result = build_elf_exec_info(kernel_buf, kernel_size, &ehdr, 0);
 
        if (result < 0) {
-- 
2.9.0


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