diff mbox series

[v12,12/16] arm64: kexec_file: add crash dump support

Message ID 20180724065759.19186-13-takahiro.akashi@linaro.org
State New
Headers show
Series arm64: kexec: add kexec_file_load() support | expand

Commit Message

AKASHI Takahiro July 24, 2018, 6:57 a.m. UTC 
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>
---
 arch/arm64/include/asm/kexec.h         |   6 +-
 arch/arm64/kernel/machine_kexec_file.c | 113 ++++++++++++++++++++++++-
 2 files changed, 115 insertions(+), 4 deletions(-)

-- 
2.18.0

Comments

James Morse July 26, 2018, 1:36 p.m. UTC | #1 
Hi Akashi,

On 24/07/18 07:57, AKASHI Takahiro wrote:
> 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


> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h

> index 5d102a1054b3..1b2c27026ae0 100644

> --- a/arch/arm64/include/asm/kexec.h

> +++ b/arch/arm64/include/asm/kexec.h

> @@ -97,8 +97,12 @@ static inline void crash_post_resume(void) {}

>  #define ARCH_HAS_KIMAGE_ARCH

>  

>  struct kimage_arch {


> -	void *dtb_buf;

> +	void *dtb;


This change should be in an earlier patch, otherwise this series doesn't build
during bisect.

With the build-issues fixed:
Reviewed-by: James Morse <james.morse@arm.com>


Some boring Nits:

>  	unsigned long dtb_mem;

> +	/* Core ELF header buffer */

> +	void *elf_headers;

> +	unsigned long elf_headers_mem;

> +	unsigned long elf_headers_sz;

>  };

> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c

> index b8297f10e2ef..7356da5a53d5 100644

> --- a/arch/arm64/kernel/machine_kexec_file.c

> +++ b/arch/arm64/kernel/machine_kexec_file.c

> @@ -38,12 +44,30 @@ static int setup_dtb(struct kimage *image,

>  		void **dtb_buf, unsigned long *dtb_buf_len)

>  {

>  	void *buf = NULL;

> -	size_t buf_size;

> +	size_t buf_size, range_size;

>  	int nodeoffset;

>  	int ret;

>  

>  	/* duplicate dt blob */

>  	buf_size = fdt_totalsize(initial_boot_params);

> +	range_size = of_fdt_reg_cells_size();

> +

> +	if (image->type == KEXEC_TYPE_CRASH) {

> +		buf_size += fdt_prop_len("linux,elfcorehdr", range_size);

> +		buf_size += fdt_prop_len("linux,usable-memory-range",

> +								range_size);

> +	}


Nit: it would be better if these strings were defined in a header file somewhere
so we don't risk a typo if this gets refactored.



> @@ -129,6 +170,43 @@ static int setup_dtb(struct kimage *image,

>  	return ret;

>  }

>  

> +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, 0,

> +							&start, &end, NULL)


Nit: MEMBLOCK_NONE


Thanks,

James
AKASHI Takahiro July 27, 2018, 7 a.m. UTC | #2 
On Thu, Jul 26, 2018 at 02:36:58PM +0100, James Morse wrote:
> Hi Akashi,

> 

> On 24/07/18 07:57, AKASHI Takahiro wrote:

> > 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

> 

> > diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h

> > index 5d102a1054b3..1b2c27026ae0 100644

> > --- a/arch/arm64/include/asm/kexec.h

> > +++ b/arch/arm64/include/asm/kexec.h

> > @@ -97,8 +97,12 @@ static inline void crash_post_resume(void) {}

> >  #define ARCH_HAS_KIMAGE_ARCH

> >  

> >  struct kimage_arch {

> 

> > -	void *dtb_buf;

> > +	void *dtb;

> 

> This change should be in an earlier patch, otherwise this series doesn't build

> during bisect.


Will fix.

> With the build-issues fixed:

> Reviewed-by: James Morse <james.morse@arm.com>

> 

> Some boring Nits:

> 

> >  	unsigned long dtb_mem;

> > +	/* Core ELF header buffer */

> > +	void *elf_headers;

> > +	unsigned long elf_headers_mem;

> > +	unsigned long elf_headers_sz;

> >  };

> > diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c

> > index b8297f10e2ef..7356da5a53d5 100644

> > --- a/arch/arm64/kernel/machine_kexec_file.c

> > +++ b/arch/arm64/kernel/machine_kexec_file.c

> > @@ -38,12 +44,30 @@ static int setup_dtb(struct kimage *image,

> >  		void **dtb_buf, unsigned long *dtb_buf_len)

> >  {

> >  	void *buf = NULL;

> > -	size_t buf_size;

> > +	size_t buf_size, range_size;

> >  	int nodeoffset;

> >  	int ret;

> >  

> >  	/* duplicate dt blob */

> >  	buf_size = fdt_totalsize(initial_boot_params);

> > +	range_size = of_fdt_reg_cells_size();

> > +

> > +	if (image->type == KEXEC_TYPE_CRASH) {

> > +		buf_size += fdt_prop_len("linux,elfcorehdr", range_size);

> > +		buf_size += fdt_prop_len("linux,usable-memory-range",

> > +								range_size);

> > +	}

> 

> Nit: it would be better if these strings were defined in a header file somewhere

> so we don't risk a typo if this gets refactored.


Nit??
Well, I do understand your concern, but it's a bit headache.
If we handle them in such a way, we may want to handle others, such as
linux,initrd-start/end, chosen and bootargs, as well in this file.
They are not kexec specific and should go into a common header. This will
end up propagating similar changes to other no-kexec-related occurrences
under drivers/of.

So I want to keep the following def's local in this file for easy
maintenance.
#define FDT_PSTR_KEXEC_ELFHDR  "linux,elfcorehdr"
#define FDT_PSTR_MEM_RANGE     "linux,usable-memory-range"
#define FDT_PSTR_INITRD_ST     "linux,initrd-start"
#define FDT_PSTR_INITRD_END    "linux,initrd-end"
#define FDT_PSTR_BOOTARGS       "bootargs"
#define FDT_PSTR_KASLR_SEED     "kaslr-seed"

> 

> 

> > @@ -129,6 +170,43 @@ static int setup_dtb(struct kimage *image,

> >  	return ret;

> >  }

> >  

> > +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, 0,

> > +							&start, &end, NULL)

> 

> Nit: MEMBLOCK_NONE


OK

-Takahiro AKASHI


> 

> Thanks,

> 

> James
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 5d102a1054b3..1b2c27026ae0 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -97,8 +97,12 @@  static inline void crash_post_resume(void) {}
 #define ARCH_HAS_KIMAGE_ARCH
 
 struct kimage_arch {
-	void *dtb_buf;
+	void *dtb;
 	unsigned long dtb_mem;
+	/* Core ELF header buffer */
+	void *elf_headers;
+	unsigned long elf_headers_mem;
+	unsigned long elf_headers_sz;
 };
 
 /**
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index b8297f10e2ef..7356da5a53d5 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -16,7 +16,9 @@ 
 #include <linux/libfdt.h>
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
+#include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/vmalloc.h>
 #include <asm/byteorder.h>
 
 const struct kexec_file_ops * const kexec_file_loaders[] = {
@@ -29,6 +31,10 @@  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);
 }
 
@@ -38,12 +44,30 @@  static int setup_dtb(struct kimage *image,
 		void **dtb_buf, unsigned long *dtb_buf_len)
 {
 	void *buf = NULL;
-	size_t buf_size;
+	size_t buf_size, range_size;
 	int nodeoffset;
 	int ret;
 
+	/* check ranges against root's #address-cells and #size-cells */
+	if (image->type == KEXEC_TYPE_CRASH &&
+		(!of_fdt_cells_size_fitted(image->arch.elf_headers_mem,
+				image->arch.elf_headers_sz) ||
+		 !of_fdt_cells_size_fitted(crashk_res.start,
+				crashk_res.end - crashk_res.start + 1))) {
+		pr_err("Crash memory region doesn't fit into DT's root cell sizes.\n");
+		ret = -EINVAL;
+		goto out_err;
+	}
+
 	/* duplicate dt blob */
 	buf_size = fdt_totalsize(initial_boot_params);
+	range_size = of_fdt_reg_cells_size();
+
+	if (image->type == KEXEC_TYPE_CRASH) {
+		buf_size += fdt_prop_len("linux,elfcorehdr", range_size);
+		buf_size += fdt_prop_len("linux,usable-memory-range",
+								range_size);
+	}
 
 	if (initrd_load_addr) {
 		/* can be redundant, but trimmed at the end */
@@ -73,6 +97,23 @@  static int setup_dtb(struct kimage *image,
 		goto out_err;
 	}
 
+	if (image->type == KEXEC_TYPE_CRASH) {
+		/* add linux,elfcorehdr */
+		ret = fdt_setprop_reg(buf, nodeoffset, "linux,elfcorehdr",
+				image->arch.elf_headers_mem,
+				image->arch.elf_headers_sz);
+		if (ret)
+			goto out_err;
+
+		/* add linux,usable-memory-range */
+		ret = fdt_setprop_reg(buf, nodeoffset,
+				"linux,usable-memory-range",
+				crashk_res.start,
+				crashk_res.end - crashk_res.start + 1);
+		if (ret)
+			goto out_err;
+	}
+
 	/* add bootargs */
 	if (cmdline) {
 		ret = fdt_setprop_string(buf, nodeoffset, "bootargs", cmdline);
@@ -129,6 +170,43 @@  static int setup_dtb(struct kimage *image,
 	return ret;
 }
 
+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, 0,
+							&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,
@@ -136,14 +214,43 @@  int load_other_segments(struct kimage *image,
 			char *cmdline, unsigned long cmdline_len)
 {
 	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;