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Subject[PATCH v3 2/2] arm64: kexec_file: add crash dump support
Date
Enabling crash dump (kdump) includes
* prepare contents of ELF header of a core dump file, /proc/vmcore,
using crash_prepare_elf64_headers(), and
* add two device tree properties, "linux,usable-memory-range" and
"linux,elfcorehdr", which represent respectively a memory range
to be used by crash dump kernel and the header's location

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
---
arch/arm64/include/asm/kexec.h | 4 +
arch/arm64/kernel/kexec_image.c | 4 -
arch/arm64/kernel/machine_kexec_file.c | 106 ++++++++++++++++++++++++-
3 files changed, 106 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 12a561a54128..d24b527e8c00 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -96,6 +96,10 @@ static inline void crash_post_resume(void) {}
struct kimage_arch {
void *dtb;
unsigned long dtb_mem;
+ /* Core ELF header buffer */
+ void *elf_headers;
+ unsigned long elf_headers_mem;
+ unsigned long elf_headers_sz;
};

extern const struct kexec_file_ops kexec_image_ops;
diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index 29a9428486a5..af9987c154ca 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -47,10 +47,6 @@ static void *image_load(struct kimage *image,
struct kexec_segment *kernel_segment;
int ret;

- /* We don't support crash kernels yet. */
- if (image->type == KEXEC_TYPE_CRASH)
- return ERR_PTR(-EOPNOTSUPP);
-
/*
* We require a kernel with an unambiguous Image header. Per
* Documentation/arm64/booting.rst, this is the case when image_size
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 7b08bf9499b6..f1d1bb895fd2 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -17,12 +17,15 @@
#include <linux/memblock.h>
#include <linux/of_fdt.h>
#include <linux/random.h>
+#include <linux/slab.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <asm/byteorder.h>

/* relevant device tree properties */
+#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr"
+#define FDT_PROP_MEM_RANGE "linux,usable-memory-range"
#define FDT_PROP_INITRD_START "linux,initrd-start"
#define FDT_PROP_INITRD_END "linux,initrd-end"
#define FDT_PROP_BOOTARGS "bootargs"
@@ -40,6 +43,10 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
vfree(image->arch.dtb);
image->arch.dtb = NULL;

+ vfree(image->arch.elf_headers);
+ image->arch.elf_headers = NULL;
+ image->arch.elf_headers_sz = 0;
+
return kexec_image_post_load_cleanup_default(image);
}

@@ -55,6 +62,31 @@ static int setup_dtb(struct kimage *image,

off = ret;

+ ret = fdt_delprop(dtb, off, FDT_PROP_KEXEC_ELFHDR);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ goto out;
+ ret = fdt_delprop(dtb, off, FDT_PROP_MEM_RANGE);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ goto out;
+
+ if (image->type == KEXEC_TYPE_CRASH) {
+ /* add linux,elfcorehdr */
+ ret = fdt_appendprop_addrrange(dtb, 0, off,
+ FDT_PROP_KEXEC_ELFHDR,
+ image->arch.elf_headers_mem,
+ image->arch.elf_headers_sz);
+ if (ret)
+ return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
+
+ /* add linux,usable-memory-range */
+ ret = fdt_appendprop_addrrange(dtb, 0, off,
+ FDT_PROP_MEM_RANGE,
+ crashk_res.start,
+ crashk_res.end - crashk_res.start + 1);
+ if (ret)
+ return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
+ }
+
/* add bootargs */
if (cmdline) {
ret = fdt_setprop_string(dtb, off, FDT_PROP_BOOTARGS, cmdline);
@@ -125,8 +157,8 @@ static int setup_dtb(struct kimage *image,
}

/*
- * More space needed so that we can add initrd, bootargs, kaslr-seed, and
- * rng-seed.
+ * More space needed so that we can add initrd, bootargs, kaslr-seed,
+ * rng-seed, userable-memory-range and elfcorehdr.
*/
#define DTB_EXTRA_SPACE 0x1000

@@ -174,6 +206,43 @@ static int create_dtb(struct kimage *image,
}
}

+static int prepare_elf_headers(void **addr, unsigned long *sz)
+{
+ struct crash_mem *cmem;
+ unsigned int nr_ranges;
+ int ret;
+ u64 i;
+ phys_addr_t start, end;
+
+ nr_ranges = 1; /* for exclusion of crashkernel region */
+ for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
+ MEMBLOCK_NONE, &start, &end, NULL)
+ nr_ranges++;
+
+ cmem = kmalloc(sizeof(struct crash_mem) +
+ sizeof(struct crash_mem_range) * nr_ranges, GFP_KERNEL);
+ if (!cmem)
+ return -ENOMEM;
+
+ cmem->max_nr_ranges = nr_ranges;
+ cmem->nr_ranges = 0;
+ for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
+ MEMBLOCK_NONE, &start, &end, NULL) {
+ cmem->ranges[cmem->nr_ranges].start = start;
+ cmem->ranges[cmem->nr_ranges].end = end - 1;
+ cmem->nr_ranges++;
+ }
+
+ /* Exclude crashkernel region */
+ ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+
+ if (!ret)
+ ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
+
+ kfree(cmem);
+ return ret;
+}
+
int load_other_segments(struct kimage *image,
unsigned long kernel_load_addr,
unsigned long kernel_size,
@@ -181,14 +250,43 @@ int load_other_segments(struct kimage *image,
char *cmdline)
{
struct kexec_buf kbuf;
- void *dtb = NULL;
- unsigned long initrd_load_addr = 0, dtb_len;
+ void *headers, *dtb = NULL;
+ unsigned long headers_sz, initrd_load_addr = 0, dtb_len;
int ret = 0;

kbuf.image = image;
/* not allocate anything below the kernel */
kbuf.buf_min = kernel_load_addr + kernel_size;

+ /* load elf core header */
+ if (image->type == KEXEC_TYPE_CRASH) {
+ ret = prepare_elf_headers(&headers, &headers_sz);
+ if (ret) {
+ pr_err("Preparing elf core header failed\n");
+ goto out_err;
+ }
+
+ kbuf.buffer = headers;
+ kbuf.bufsz = headers_sz;
+ kbuf.mem = 0;
+ kbuf.memsz = headers_sz;
+ kbuf.buf_align = SZ_64K; /* largest supported page size */
+ kbuf.buf_max = ULONG_MAX;
+ kbuf.top_down = true;
+
+ ret = kexec_add_buffer(&kbuf);
+ if (ret) {
+ vfree(headers);
+ goto out_err;
+ }
+ image->arch.elf_headers = headers;
+ image->arch.elf_headers_mem = kbuf.mem;
+ image->arch.elf_headers_sz = headers_sz;
+
+ pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+ image->arch.elf_headers_mem, headers_sz, headers_sz);
+ }
+
/* load initrd */
if (initrd) {
kbuf.buffer = initrd;
--
2.24.0
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