[PATCH 0/3] arm64: kexec_file: add kdump

[PATCH 0/3] arm64: kexec_file: add kdump

[AKASHI Takahiro]

This is the last piece of my kexec_file_load implementation for arm64.
It is now ready for being merged as some relevant patch to dtc/libfdt[1]
has finally been integrated in v5.3-rc1.
(Nothing changed since kexec_file v16[2] except adding Patch#1 and #2.)

Patch#1 and #2 are preliminary patches for libfdt component.
Patch#3 is to add kdump support.

[1] commit 9bb9c6a110ea ("scripts/dtc: Update to upstream version
    v1.5.0-23-g87963ee20693"), in particular
	7fcf8208b8a9 libfdt: add fdt_append_addrrange()
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-November/612641.html

AKASHI Takahiro (3):
  libfdt: define UINT32_MAX in libfdt_env.h
  libfdt: include fdt_addresses.c
  arm64: kexec_file: add crash dump support

 arch/arm64/include/asm/kexec.h         |   4 +
 arch/arm64/kernel/kexec_image.c        |   4 -
 arch/arm64/kernel/machine_kexec_file.c | 105 ++++++++++++++++++++++++-
 include/linux/libfdt_env.h             |   3 +
 lib/Makefile                           |   2 +-
 lib/fdt_addresses.c                    |   2 +
 6 files changed, 112 insertions(+), 8 deletions(-)
 create mode 100644 lib/fdt_addresses.c

-- 
2.21.0


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[PATCH 1/3] libfdt: define UINT32_MAX in libfdt_env.h

[AKASHI Takahiro]

In the implementation of kexec_file_load-based kdump for arm64,
fdt_appendprop_addrrange() will be used, but fdt_addresses.c
will fail to compile due to missing UINT32_MAX.

So just define it in libfdt_env.h.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
---
 include/linux/libfdt_env.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/libfdt_env.h b/include/linux/libfdt_env.h
index edb0f0c30904..9ca00f11d9b1 100644
--- a/include/linux/libfdt_env.h
+++ b/include/linux/libfdt_env.h
@@ -3,6 +3,7 @@
 #define LIBFDT_ENV_H
 
 #include <linux/kernel.h>	/* For INT_MAX */
+#include <linux/limits.h>	/* For UINT32_MAX */
 #include <linux/string.h>
 
 #include <asm/byteorder.h>
@@ -11,6 +12,8 @@ typedef __be16 fdt16_t;
 typedef __be32 fdt32_t;
 typedef __be64 fdt64_t;
 
+#define UINT32_MAX U32_MAX
+
 #define fdt32_to_cpu(x) be32_to_cpu(x)
 #define cpu_to_fdt32(x) cpu_to_be32(x)
 #define fdt64_to_cpu(x) be64_to_cpu(x)
-- 
2.21.0


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[PATCH 2/3] libfdt: include fdt_addresses.c

[AKASHI Takahiro]

In the implementation of kexec_file_loaded-based kdump for arm64,
fdt_appendprop_addrrange() will be needed.

So include fdt_addresses.c in making libfdt.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
---
 lib/Makefile        | 2 +-
 lib/fdt_addresses.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)
 create mode 100644 lib/fdt_addresses.c

diff --git a/lib/Makefile b/lib/Makefile
index 29c02a924973..59f082727503 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -224,7 +224,7 @@ KASAN_SANITIZE_stackdepot.o := n
 KCOV_INSTRUMENT_stackdepot.o := n
 
 libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \
-	       fdt_empty_tree.o
+	       fdt_empty_tree.o fdt_addresses.o
 $(foreach file, $(libfdt_files), \
 	$(eval CFLAGS_$(file) = -I $(srctree)/scripts/dtc/libfdt))
 lib-$(CONFIG_LIBFDT) += $(libfdt_files)
diff --git a/lib/fdt_addresses.c b/lib/fdt_addresses.c
new file mode 100644
index 000000000000..23610bcf390b
--- /dev/null
+++ b/lib/fdt_addresses.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_addresses.c"
-- 
2.21.0


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[PATCH 3/3] arm64: kexec_file: add crash dump support

[AKASHI Takahiro]

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 | 105 ++++++++++++++++++++++++-
 3 files changed, 106 insertions(+), 7 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 2514fd6f12cb..60cedfa9529b 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 58871333737a..f5276e27c12b 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"
@@ -38,6 +41,10 @@ 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);
 }
 
@@ -53,6 +60,31 @@ 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);
@@ -110,7 +142,8 @@ static int setup_dtb(struct kimage *image,
 }
 
 /*
- * More space needed so that we can add initrd, bootargs and kaslr-seed.
+ * More space needed so that we can add initrd, bootargs, kaslr-seed,
+ * userable-memory-range and elfcorehdr.
  */
 #define DTB_EXTRA_SPACE 0x1000
 
@@ -158,6 +191,43 @@ 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,
@@ -165,14 +235,43 @@ 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;
-- 
2.21.0


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Re: [PATCH 0/3] arm64: kexec_file: add kdump

[AKASHI Takahiro]

Reminder.
This patch set is still applicable to v5.4-rc although there is one minor
conflict in a comment; It is trivial and can easily be fixed.

While this patch works on v5.4, we cannot read a generated core dump
file with crash command, even, of the latest v7.2.7. This is due to
a newly added 52-bit address support (and related changes in mm).
The issue, as a nature of kdump, does exist with *legacy*
(non-kexec_file_load-based) kdump, too.
(We will need a kernel patch as well as patches on crash to fix the issue
and some guys have already been working.)

So I'd like to request you to keep reviewing my patch.

Thanks,
-Takahiro Akashi


On Thu, Sep 12, 2019 at 03:01:47PM +0900, AKASHI Takahiro wrote:
> This is the last piece of my kexec_file_load implementation for arm64.
> It is now ready for being merged as some relevant patch to dtc/libfdt[1]
> has finally been integrated in v5.3-rc1.
> (Nothing changed since kexec_file v16[2] except adding Patch#1 and #2.)
> 
> Patch#1 and #2 are preliminary patches for libfdt component.
> Patch#3 is to add kdump support.
> 
> [1] commit 9bb9c6a110ea ("scripts/dtc: Update to upstream version
>     v1.5.0-23-g87963ee20693"), in particular
> 	7fcf8208b8a9 libfdt: add fdt_append_addrrange()
> [2] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-November/612641.html
> 
> AKASHI Takahiro (3):
>   libfdt: define UINT32_MAX in libfdt_env.h
>   libfdt: include fdt_addresses.c
>   arm64: kexec_file: add crash dump support
> 
>  arch/arm64/include/asm/kexec.h         |   4 +
>  arch/arm64/kernel/kexec_image.c        |   4 -
>  arch/arm64/kernel/machine_kexec_file.c | 105 ++++++++++++++++++++++++-
>  include/linux/libfdt_env.h             |   3 +
>  lib/Makefile                           |   2 +-
>  lib/fdt_addresses.c                    |   2 +
>  6 files changed, 112 insertions(+), 8 deletions(-)
>  create mode 100644 lib/fdt_addresses.c
> 
> -- 
> 2.21.0
> 

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