Re: [PATCH v9 07/11] arm64: kexec_file: add crash dump support
From: James Morse <james.morse@arm.com>
Date: 2018-05-15 17:16:07
Also in:
kexec, linux-arm-kernel, lkml
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
quoted hunk
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",