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SubjectRe: [PATCH v4 08/10] arm64: kexec_file: set up for crash dump adding elf core header
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On 02/10/17 07:14, AKASHI Takahiro wrote:
> load_crashdump_segments() creates and loads a memory segment of elf core
> header for crash dump.
>
> "linux,usable-memory-range" and "linux,elfcorehdr" will add to the 2nd
> kernel's device-tree blob. The logic of this cod is also from kexec-tools.
>
> 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 | 5 ++
> arch/arm64/kernel/machine_kexec_file.c | 149 +++++++++++++++++++++++++++++++++
> kernel/kexec_file.c | 2 +-
> 3 files changed, 155 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
> index 2fadd3cbf3af..edb702e64a8a 100644
> --- a/arch/arm64/include/asm/kexec.h
> +++ b/arch/arm64/include/asm/kexec.h
> @@ -98,6 +98,10 @@ static inline void crash_post_resume(void) {}
>
> struct kimage_arch {
> void *dtb_buf;
> + /* Core ELF header buffer */
> + void *elf_headers;
> + unsigned long elf_headers_sz;
> + unsigned long elf_load_addr;
> };
>
> struct kimage;
> @@ -113,6 +117,7 @@ extern int load_other_segments(struct kimage *image,
> unsigned long kernel_load_addr,
> char *initrd, unsigned long initrd_len,
> char *cmdline, unsigned long cmdline_len);
> +extern int load_crashdump_segments(struct kimage *image);
> #endif
>
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index 8a09d89f6266..1d30b4773af5 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -32,6 +32,10 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
> vfree(image->arch.dtb_buf);
> image->arch.dtb_buf = NULL;
>
> + vfree(image->arch.elf_headers);
> + image->arch.elf_headers = NULL;
> + image->arch.elf_headers_sz = 0;
> +
> return _kexec_kernel_post_load_cleanup(image);
> }
>
> @@ -48,6 +52,77 @@ int arch_kexec_walk_mem(struct kexec_buf *kbuf, int (*func)(u64, u64, void *))
> return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> }
>
> +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;
> + int i;
> +
> + if (cells == 1) {
> + val32 = cpu_to_fdt32((u32)val64);
> + memcpy(buf, &val32, sizeof(val32));
> + } else {
> + for (i = 0; i < (cells * sizeof(u32) - sizeof(u64)); i++)
> + *(char *)buf++ = 0;
> +

Should we use memset for this?

> + 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)
> +{
> + u64 range[2];

Could we just add some BUG/WARN when either __dt_root_addr_cells or
__dt_root_size_cells is greater than 2?

Both to make sure we have sane values and because it will be easier to
debug than overwriting things on the stack.

> + void *prop;
> + size_t buf_size;
> + int result;
> +
> + prop = range;
> + buf_size = (__dt_root_addr_cells + __dt_root_size_cells) * sizeof(u32);
> +
> + fill_property(prop, addr, __dt_root_addr_cells);
> + prop += __dt_root_addr_cells * sizeof(u32);
> +
> + fill_property(prop, size, __dt_root_size_cells);
> + prop += __dt_root_size_cells * sizeof(u32);

This is not needed (or at least we aren't doing anything with it).

Apart from that, patch seems fine.

Cheers,

> +
> + result = fdt_setprop(fdt, nodeoffset, name, range, buf_size);
> +
> + return result;
> +}
> +
> int setup_dtb(struct kimage *image,
> unsigned long initrd_load_addr, unsigned long initrd_len,
> char *cmdline, unsigned long cmdline_len,
> @@ -60,10 +135,26 @@ 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("initrd-start", sizeof(u64))
> + fdt_prop_len("initrd-end", sizeof(u64));
> @@ -85,6 +176,23 @@ 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",
> @@ -211,3 +319,44 @@ int load_other_segments(struct kimage *image, unsigned long kernel_load_addr,
> image->arch.dtb_buf = NULL;
> return ret;
> }
> +
> +int load_crashdump_segments(struct kimage *image)
> +{
> + void *elf_addr;
> + unsigned long elf_sz;
> + struct kexec_buf kbuf;
> + int ret;
> +
> + if (image->type != KEXEC_TYPE_CRASH)
> + return 0;
> +
> + /* Prepare elf headers and add a segment */
> + ret = prepare_elf_headers(image, &elf_addr, &elf_sz);
> + if (ret) {
> + pr_err("Preparing elf core header failed\n");
> + return ret;
> + }
> +
> + kbuf.image = image;
> + kbuf.buffer = elf_addr;
> + kbuf.bufsz = elf_sz;
> + kbuf.memsz = elf_sz;
> + kbuf.buf_align = PAGE_SIZE;
> + kbuf.buf_min = crashk_res.start;
> + kbuf.buf_max = crashk_res.end + 1;
> + kbuf.top_down = 1;
> +
> + ret = kexec_add_buffer(&kbuf);
> + if (ret) {
> + vfree(elf_addr);
> + return ret;
> + }
> + image->arch.elf_headers = elf_addr;
> + image->arch.elf_headers_sz = elf_sz;
> + image->arch.elf_load_addr = kbuf.mem;
> +
> + pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
> + image->arch.elf_load_addr, elf_sz, elf_sz);
> +
> + return ret;
> +}
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 8a7f029c5995..82a98f284cf5 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -1340,7 +1340,7 @@ static int prepare_elf64_headers(struct crash_elf_data *ced,
> phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
> (ehdr->e_phnum)++;
>
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> /* Prepare PT_LOAD type program header for kernel text region */
> phdr = (Elf64_Phdr *)bufp;
> bufp += sizeof(Elf64_Phdr);
>

--
Julien Thierry

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