Re: [PATCH v1 2/4] kexec: Add common device tree routines

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Tue, Jul 19, 2016 at 11:28:13PM +0000, Geoff Levand wrote:
> Common device tree routines that can be shared between all arches
> that have device tree support.
> 
> Signed-off-by: Geoff Levand <geoff@infradead.org>
> ---
>  kexec/Makefile |   4 ++
>  kexec/dt-ops.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  kexec/dt-ops.h |  13 ++++++
>  3 files changed, 156 insertions(+)
>  create mode 100644 kexec/dt-ops.c
>  create mode 100644 kexec/dt-ops.h
> 
> diff --git a/kexec/Makefile b/kexec/Makefile
> index e2aee84..cc3f08b 100644
> --- a/kexec/Makefile
> +++ b/kexec/Makefile
> @@ -73,6 +73,10 @@ dist				+= kexec/mem_regions.c kexec/mem_regions.h
>  $(ARCH)_MEM_REGIONS		=
>  KEXEC_SRCS			+= $($(ARCH)_MEM_REGIONS)
>  
> +dist				+= kexec/dt-ops.c kexec/dt-ops.h
> +$(ARCH)_DT_OPS		=
> +KEXEC_SRCS			+= $($(ARCH)_DT_OPS)
> +
>  include $(srcdir)/kexec/arch/alpha/Makefile
>  include $(srcdir)/kexec/arch/arm/Makefile
>  include $(srcdir)/kexec/arch/i386/Makefile
> diff --git a/kexec/dt-ops.c b/kexec/dt-ops.c
> new file mode 100644
> index 0000000..060776a
> --- /dev/null
> +++ b/kexec/dt-ops.c
> @@ -0,0 +1,139 @@
> +#include <assert.h>
> +#include <errno.h>
> +#include <inttypes.h>
> +#include <libfdt.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +#include "kexec.h"
> +#include "dt-ops.h"
> +
> +static const char n_chosen[] = "/chosen";
> +
> +static const char p_bootargs[] = "bootargs";
> +static const char p_initrd_start[] = "linux,initrd-start";
> +static const char p_initrd_end[] = "linux,initrd-end";
> +
> +int dtb_set_initrd(char **dtb, off_t *dtb_size, off_t start, off_t end)
> +{
> +	int result;
> +	uint64_t value;
> +
> +	dbgprintf("%s: start %jd, end %jd, size %jd (%jd KiB)\n",
> +		__func__, (intmax_t)start, (intmax_t)end,
> +		(intmax_t)(end - start),
> +		(intmax_t)(end - start) / 1024);
> +
> +	value = cpu_to_fdt64(start);
> +
> +	result = dtb_set_property(dtb, dtb_size, n_chosen, p_initrd_start,
> +		&value, sizeof(value));
> +
> +	if (result)
> +		return result;
> +
> +	value = cpu_to_fdt64(end);
> +
> +	result = dtb_set_property(dtb, dtb_size, n_chosen, p_initrd_end,
> +		&value, sizeof(value));
> +
> +	if (result) {
> +		dtb_delete_property(*dtb, n_chosen, p_initrd_start);
> +		return result;
> +	}
> +
> +	return 0;
> +}
> +
> +int dtb_set_bootargs(char **dtb, off_t *dtb_size, const char *command_line)
> +{
> +	return dtb_set_property(dtb, dtb_size, n_chosen, p_bootargs,
> +		command_line, strlen(command_line) + 1);
> +}
> +
> +int dtb_set_property(char **dtb, off_t *dtb_size, const char *node,
> +	const char *prop, const void *value, int value_len)
> +{
> +	int result;
> +	int nodeoffset;
> +	void *new_dtb;
> +	int new_size;
> +
> +	value_len = FDT_TAGALIGN(value_len);
> +
> +	new_size = FDT_TAGALIGN(*dtb_size + fdt_node_len(node)
> +		+ fdt_prop_len(prop, value_len));

As James pointed out before, this will increase the size of dtb
if kexec is executed repeatedly.

> +	new_dtb = malloc(new_size);
> +
> +	if (!new_dtb) {
> +		dbgprintf("%s: malloc failed\n", __func__);
> +		return -ENOMEM;
> +	}
> +
> +	result = fdt_open_into(*dtb, new_dtb, new_size);
> +
> +	if (result) {
> +		dbgprintf("%s: fdt_open_into failed: %s\n", __func__,
> +			fdt_strerror(result));
> +		goto on_error;
> +	}
> +
> +	nodeoffset = fdt_path_offset(new_dtb, node);
> +	
> +	if (nodeoffset == -FDT_ERR_NOTFOUND) {
> +		result = fdt_add_subnode(new_dtb, nodeoffset, node);
> +
> +		if (result) {
> +			dbgprintf("%s: fdt_add_subnode failed: %s\n", __func__,
> +				fdt_strerror(result));
> +			goto on_error;
> +		}
> +	} else if (nodeoffset < 0) {
> +		dbgprintf("%s: fdt_path_offset failed: %s\n", __func__,
> +			fdt_strerror(nodeoffset));
> +		goto on_error;
> +	}
> +
> +	result = fdt_setprop(new_dtb, nodeoffset, prop, value, value_len);
> +
> +	if (result) {
> +		dbgprintf("%s: fdt_setprop failed: %s\n", __func__,
> +			fdt_strerror(result));
> +		goto on_error;
> +	}
> +
> +	/*
> +	 * Can't call free on dtb since dtb may have been mmaped by
> +	 * slurp_file().
> +	 */
> +
> +	*dtb = new_dtb;
> +	*dtb_size = new_size;

So you might better call fdt_pack(), which will set "totalsize" of
the blob to an appropriate value.

Thanks,
-Takahiro AKASHI

> +	return 0;
> +
> +on_error:
> +	free(new_dtb);
> +	return result;
> +}
> +
> +int dtb_delete_property(char *dtb, const char *node, const char *prop)
> +{
> +	int result;
> +	int nodeoffset = fdt_path_offset(dtb, node);
> +
> +	if (nodeoffset < 0) {
> +		dbgprintf("%s: fdt_path_offset failed: %s\n", __func__,
> +			fdt_strerror(nodeoffset));
> +		return nodeoffset;
> +	}
> +
> +	result = fdt_delprop(dtb, nodeoffset, prop);
> +
> +	if (result)
> +		dbgprintf("%s: fdt_delprop failed: %s\n", __func__,
> +			fdt_strerror(nodeoffset));
> +
> +	return result;
> +}
> diff --git a/kexec/dt-ops.h b/kexec/dt-ops.h
> new file mode 100644
> index 0000000..e70d15d
> --- /dev/null
> +++ b/kexec/dt-ops.h
> @@ -0,0 +1,13 @@
> +#if !defined(KEXEC_DT_OPS_H)
> +#define KEXEC_DT_OPS_H
> +
> +#include <sys/types.h>
> +
> +int dtb_set_initrd(char **dtb, off_t *dtb_size, off_t start, off_t end);
> +int dtb_set_bootargs(char **dtb, off_t *dtb_size, const char *command_line);
> +int dtb_set_property(char **dtb, off_t *dtb_size, const char *node,
> +	const char *prop, const void *value, int value_len);
> +
> +int dtb_delete_property(char *dtb, const char *node, const char *prop);
> +
> +#endif
> -- 
> 2.5.0
> 
> 

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