[PATCH v3 0/2] arm64: kexec_file: add kdump

[PATCH v3 0/2] 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.)

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

Bhepesh's patch[3] will be required for 52-bit VA support either against
legacy kexec or kexec_file.
Once this patch is applied, whether or not CONFIG_ARM64_VA_BITS_52 is
enabled or not, a matching fix[4] on user space side, crash utility,
will also be needed. 
# NOTE:
# As of v5.5-rc1, crash utility doesn't work due to the commit
# b6e43c0e3129 ("arm64: remove __exception annotations").
# But the fix is trivial and it won't affect this kernel patch.

Anyway, I tested my patch, at least, with the following configuration:
1) CONFIG_ARM64_BITS_48=y
2) CONFIG_ARM64_BITS_52=y, but vabits_actual=48

(I don't have any platform to use for
3) CONFIG_ARM64_BITS_52=y, and vabits_actual=52)

[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
[3] http://lists.infradead.org/pipermail/linux-arm-kernel/2019-November/693411.html
[4] https://www.redhat.com/archives/crash-utility/2019-November/msg00014.html

Changes in v3 (Dec 9, 2019)
* rebased to v5.5-rc1
* remove v2's patch#2 as the same fix has been applied
* Otherwise, no functional changes (since v1)

Changes in v2 (Nov 14, 2019)
* rebased to v5.4-rc7
* no functional changes

v1 (Sept 12, 2019)
* on top of v5.3-rc8

AKASHI Takahiro (2):
  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 | 106 ++++++++++++++++++++++++-
 lib/Makefile                           |   2 +-
 lib/fdt_addresses.c                    |   2 +
 5 files changed, 109 insertions(+), 9 deletions(-)
 create mode 100644 lib/fdt_addresses.c

-- 
2.24.0


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[PATCH v3 1/2] 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 93217d44237f..c20b1debe9b4 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -223,7 +223,7 @@ 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"
-- 
2.24.0


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[PATCH v3 2/2] 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 | 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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Re: [PATCH v3 1/2] libfdt: include fdt_addresses.c

[Will Deacon]

On Mon, Dec 09, 2019 at 12:03:44PM +0900, AKASHI Takahiro wrote:
> 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

I'd like to take this via arm64 and it looks like it follows what we do
for other fdt files under lib/.

Rob, Frank -- are you ok with me picking this up, please?

Will


> diff --git a/lib/Makefile b/lib/Makefile
> index 93217d44237f..c20b1debe9b4 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -223,7 +223,7 @@ 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"
> -- 
> 2.24.0

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