Messages in this thread | | | Subject | Re: [RFC PATCH 2/4] of: Add a common kexec FDT setup function | From | Lakshmi Ramasubramanian <> | Date | Fri, 11 Dec 2020 17:18:36 -0800 |
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On 12/11/20 2:10 PM, Rob Herring wrote:
Hi Rob,
> Both arm64 and powerpc do essentially the same FDT /chosen setup for > kexec. We can simply combine everything each arch does. The differences > are either omissions that arm64 should have or additional properties > that will be ignored. > > The differences relative to the arm64 version: > - If /chosen doesn't exist, it will be created (should never happen). > - Any old dtb and initrd reserved memory will be released. > - The new initrd and elfcorehdr are marked reserved. > - "linux,booted-from-kexec" is set. > > The differences relative to the powerpc version: > - "kaslr-seed" and "rng-seed" may be set. > - "linux,elfcorehdr" is set. > - Any existing "linux,usable-memory-range" is removed. > > Signed-off-by: Rob Herring <robh@kernel.org> > --- > This could be taken a step further and do the allocation of the new > FDT. The difference is arm64 uses vmalloc and powerpc uses kmalloc. The > arm64 version also retries with a bigger allocation. That seems > unnecessary. > --- > drivers/of/Makefile | 1 + > drivers/of/kexec.c | 228 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 5 + > 3 files changed, 234 insertions(+) > create mode 100644 drivers/of/kexec.c > > diff --git a/drivers/of/Makefile b/drivers/of/Makefile > index 6e1e5212f058..8ce11955afde 100644 > --- a/drivers/of/Makefile > +++ b/drivers/of/Makefile > @@ -13,5 +13,6 @@ obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o > obj-$(CONFIG_OF_RESOLVE) += resolver.o > obj-$(CONFIG_OF_OVERLAY) += overlay.o > obj-$(CONFIG_OF_NUMA) += of_numa.o > +obj-$(CONFIG_KEXEC_FILE) += kexec.o
For the functions moved from powerpc & arm64 to "drivers/of/kexec.c" in this patch, compiling kexec.c when CONFIG_KEXEC_FILE is enabled is fine. But when more functions (such as remove_ima_buffer()) are moved to this file, Makefile needs to be updated for other ima kexec related CONFIGs.
Why not compile kexec.c when CONFIG_OF_FLATTREE is enabled, and handle other CONFIGs using IS_ENABLED (like you'd suggested earlier)?
> > obj-$(CONFIG_OF_UNITTEST) += unittest-data/ > diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c > new file mode 100644 > index 000000000000..66787be081fe > --- /dev/null > +++ b/drivers/of/kexec.c > @@ -0,0 +1,228 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2020 Arm Limited > + * > + * Based on arch/arm64/kernel/machine_kexec_file.c: > + * Copyright (C) 2018 Linaro Limited > + * > + * And arch/powerpc/kexec/file_load.c: > + * Copyright (C) 2016 IBM Corporation > + */ > + > +#include <linux/kernel.h> > +#include <linux/kexec.h> > +#include <linux/libfdt.h> > +#include <linux/of.h> > +#include <linux/of_fdt.h> > +#include <linux/random.h> > +#include <linux/types.h> > + > +/* relevant device tree properties */ > +#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr" > +#define FDT_PROP_MEM_RANGE "linux,usable-memory-range" > +#define FDT_PROP_INITRD_START "linux,initrd-start" > +#define FDT_PROP_INITRD_END "linux,initrd-end" > +#define FDT_PROP_BOOTARGS "bootargs" > +#define FDT_PROP_KASLR_SEED "kaslr-seed" > +#define FDT_PROP_RNG_SEED "rng-seed" > +#define RNG_SEED_SIZE 128
> + > +/** > + * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size > + * > + * Return: 0 on success, or negative errno on error. > + */ > +static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size) > +{ > + int i, ret, num_rsvs = fdt_num_mem_rsv(fdt); > + > + for (i = 0; i < num_rsvs; i++) { > + u64 rsv_start, rsv_size; > + > + ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size); > + if (ret) { > + pr_err("Malformed device tree.\n"); > + return -EINVAL; > + } > + > + if (rsv_start == start && rsv_size == size) { > + ret = fdt_del_mem_rsv(fdt, i); > + if (ret) { > + pr_err("Error deleting device tree reservation.\n"); > + return -EINVAL; > + } > + > + return 0; > + } > + } > + > + return -ENOENT; > +} > + > +/* > + * of_kexec_setup_new_fdt - modify /chosen and memory reservation for the next kernel > + * > + * @image: kexec image being loaded. > + * @fdt: Flattened device tree for the next kernel. > + * @initrd_load_addr: Address where the next initrd will be loaded. > + * @initrd_len: Size of the next initrd, or 0 if there will be none. > + * @cmdline: Command line for the next kernel, or NULL if there will > + * be none. nit: alignment of the parameter description seems to be off. But it could be due to my mail client.
> + * > + * Return: 0 on success, or negative errno on error. > + */ > +int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt, > + unsigned long initrd_load_addr, unsigned long initrd_len, > + const char *cmdline) > +{ > + int ret, chosen_node; > + const void *prop; > + > + /* Remove memory reservation for the current device tree. */ > + ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params), > + fdt_totalsize(initial_boot_params)); > + if (ret == -EINVAL) > + return ret; > + > + chosen_node = fdt_path_offset(fdt, "/chosen"); > + if (chosen_node == -FDT_ERR_NOTFOUND) > + chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"), > + "chosen"); > + if (chosen_node < 0) { > + ret = chosen_node; > + goto out; > + } > + > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_ELFHDR); > + if (ret && ret != -FDT_ERR_NOTFOUND) > + goto out; > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_MEM_RANGE); > + if (ret && ret != -FDT_ERR_NOTFOUND) > + goto out; > + > + /* Did we boot using an initrd? */ > + prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL); > + if (prop) { > + u64 tmp_start, tmp_end, tmp_size; > + > + tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop)); > + > + prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL); > + if (!prop) > + return -EINVAL; > + > + tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop)); > + > + /* > + * kexec reserves exact initrd size, while firmware may > + * reserve a multiple of PAGE_SIZE, so check for both. > + */ > + tmp_size = tmp_end - tmp_start; > + ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size); > + if (ret == -ENOENT) > + ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, > + round_up(tmp_size, PAGE_SIZE)); > + if (ret == -EINVAL) > + return ret; > + } > + > + /* add initrd-* */ > + if (initrd_load_addr) { > + ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_START, > + initrd_load_addr); > + if (ret) > + goto out; > + > + ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_END, > + initrd_load_addr + initrd_len); > + if (ret) > + goto out; > + > + ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len); > + if (ret) > + goto out; > + > + } else { > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_START); > + if (ret && (ret != -FDT_ERR_NOTFOUND)) > + goto out; > + > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_END); > + if (ret && (ret != -FDT_ERR_NOTFOUND)) > + goto out; > + } > + > + if (image->type == KEXEC_TYPE_CRASH) { > + /* add linux,elfcorehdr */ > + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, > + FDT_PROP_KEXEC_ELFHDR, > + image->arch.elf_headers_mem, > + image->arch.elf_headers_sz); > + if (ret) > + goto out; > + > + /* > + * Avoid elfcorehdr from being stomped on in kdump kernel by > + * setting up memory reserve map. > + */ > + ret = fdt_add_mem_rsv(fdt, image->arch.elf_headers_mem, > + image->arch.elf_headers_sz); Return value from fdt_add_mem_rsv() should be checked.
> + > + /* add linux,usable-memory-range */ > + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, > + FDT_PROP_MEM_RANGE, > + crashk_res.start, > + crashk_res.end - crashk_res.start + 1); > + if (ret) > + goto out; > + } > + > + /* add bootargs */ > + if (cmdline) { > + ret = fdt_setprop_string(fdt, chosen_node, FDT_PROP_BOOTARGS, cmdline); > + if (ret) > + goto out; > + } else { > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_BOOTARGS); > + if (ret && (ret != -FDT_ERR_NOTFOUND)) > + goto out; > + } > + > + /* add kaslr-seed */ > + ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KASLR_SEED); > + if (ret == -FDT_ERR_NOTFOUND) > + ret = 0; > + else if (ret) > + goto out; > + > + if (rng_is_initialized()) { > + u64 seed = get_random_u64(); > + ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_KASLR_SEED, seed); > + if (ret) > + goto out; > + } else { > + pr_notice("RNG is not initialised: omitting \"%s\" property\n", > + FDT_PROP_KASLR_SEED); > + } > + > + /* add rng-seed */ > + if (rng_is_initialized()) { > + void *rng_seed; > + ret = fdt_setprop_placeholder(fdt, chosen_node, FDT_PROP_RNG_SEED, > + RNG_SEED_SIZE, &rng_seed); > + if (ret) > + goto out; > + get_random_bytes(rng_seed, RNG_SEED_SIZE); > + } else { > + pr_notice("RNG is not initialised: omitting \"%s\" property\n", > + FDT_PROP_RNG_SEED); > + } > + > + ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0); > + > +out: > + if (ret) > + return (ret == -FDT_ERR_NOSPACE) ? -ENOMEM : -EINVAL; > + > + return 0; > +} > diff --git a/include/linux/of.h b/include/linux/of.h > index 5d51891cbf1a..3375f5295875 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -558,6 +558,11 @@ int of_map_id(struct device_node *np, u32 id, > const char *map_name, const char *map_mask_name, > struct device_node **target, u32 *id_out); > > +struct kimage; > +int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt, > + unsigned long initrd_load_addr, unsigned long initrd_len, > + const char *cmdline);
of_kexec_setup_new_fdt() should only be declared if CONFIG_KEXEC_FILE is enabled. Right?
-lakshmi
> + > #else /* CONFIG_OF */ > > static inline void of_core_init(void) >
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