Hi guys,
(CC: +RobH, devicetree list)
On 25/04/18 07:26, 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 repsectively a memory range
> to be used by crash dump kernel and the header's location
kexec_file_load() on arm64 needs to be able to create a prop encoded array to
the FDT, but there doesn't appear to be a libfdt helper to do this.
Akashi's code below adds fdt_setprop_range() to the arch code, and duplicates
bits of libfdt_internal.h to do the work.
How should this be done? I'm assuming this is something we need a new API in
libfdt.h for. How do these come about, and is there an interim step we can use
until then?
Thanks!
James
> diff --git a/arch/arm64/kernel/machine_kexec_file.c
> b/arch/arm64/kernel/machine_kexec_file.c
> index 37c0a9dc2e47..ec674f4d267c 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -76,6 +81,78 @@ int arch_kexec_walk_mem(struct kexec_buf *kbuf,
> return ret;
> }
>
> +static int __init arch_kexec_file_init(void)
> +{
> + /* Those values are used later on loading the kernel */
> + __dt_root_addr_cells = dt_root_addr_cells;
> + __dt_root_size_cells = dt_root_size_cells;
> +
> + return 0;
> +}
> +late_initcall(arch_kexec_file_init);
> +
> +#define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
> +#define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE))
> +
> +static int fdt_prop_len(const char *prop_name, int len)
> +{
> + return (strlen(prop_name) + 1) +
> + sizeof(struct fdt_property) +
> + FDT_TAGALIGN(len);
> +}
> +
> +static bool cells_size_fitted(unsigned long base, unsigned long size)
> +{
> + /* if *_cells >= 2, cells can hold 64-bit values anyway */
> + if ((__dt_root_addr_cells == 1) && (base >= (1ULL << 32)))
> + return false;
> +
> + if ((__dt_root_size_cells == 1) && (size >= (1ULL << 32)))
> + return false;
> +
> + return true;
> +}
> +
> +static void fill_property(void *buf, u64 val64, int cells)
> +{
> + u32 val32;
> +
> + if (cells == 1) {
> + val32 = cpu_to_fdt32((u32)val64);
> + memcpy(buf, &val32, sizeof(val32));
> + } else {
> + memset(buf, 0, cells * sizeof(u32) - sizeof(u64));
> + buf += cells * sizeof(u32) - sizeof(u64);
> +
> + val64 = cpu_to_fdt64(val64);
> + memcpy(buf, &val64, sizeof(val64));
> + }
> +}
> +
> +static int fdt_setprop_range(void *fdt, int nodeoffset, const char *name,
> + unsigned long addr, unsigned long size)
> +{
> + void *buf, *prop;
> + size_t buf_size;
> + int result;
> +
> + buf_size = (__dt_root_addr_cells + __dt_root_size_cells) * sizeof(u32);
> + prop = buf = vmalloc(buf_size);
> + if (!buf)
> + return -ENOMEM;
> +
> + fill_property(prop, addr, __dt_root_addr_cells);
> + prop += __dt_root_addr_cells * sizeof(u32);
> +
> + fill_property(prop, size, __dt_root_size_cells);
> +
> + result = fdt_setprop(fdt, nodeoffset, name, buf, buf_size);
> +
> + vfree(buf);
> +
> + return result;
> +}
> +
> static int setup_dtb(struct kimage *image,
> unsigned long initrd_load_addr, unsigned long initrd_len,
> char *cmdline, unsigned long cmdline_len,
> @@ -88,10 +165,26 @@ static int setup_dtb(struct kimage *image,
> int range_len;
> int ret;
>
> + /* check ranges against root's #address-cells and #size-cells */
> + if (image->type == KEXEC_TYPE_CRASH &&
> + (!cells_size_fitted(image->arch.elf_load_addr,
> + image->arch.elf_headers_sz) ||
> + !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_len = (__dt_root_addr_cells + __dt_root_size_cells) * sizeof(u32);
>
> + if (image->type == KEXEC_TYPE_CRASH)
> + buf_size += fdt_prop_len("linux,elfcorehdr", range_len)
> + + fdt_prop_len("linux,usable-memory-range",
> + range_len);
> +
> if (initrd_load_addr)
> buf_size += fdt_prop_len("linux,initrd-start", sizeof(u64))
> + fdt_prop_len("linux,initrd-end", sizeof(u64));
> @@ -113,6 +206,23 @@ static int setup_dtb(struct kimage *image,
> if (nodeoffset < 0)
> goto out_err;
>
> + if (image->type == KEXEC_TYPE_CRASH) {
> + /* add linux,elfcorehdr */
> + ret = fdt_setprop_range(buf, nodeoffset, "linux,elfcorehdr",
> + image->arch.elf_load_addr,
> + image->arch.elf_headers_sz);
> + if (ret)
> + goto out_err;
> +
> + /* add linux,usable-memory-range */
> + ret = fdt_setprop_range(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(buf, nodeoffset, "bootargs",
