Hi Rob, On Fri, May 18, 2018 at 10:35:52AM -0500, Rob Herring wrote: > On Tue, May 15, 2018 at 06:12:59PM +0100, James Morse wrote: > > Hi guys, > > > > (CC: +RobH, devicetree list) > > Thanks. > > > 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 > > BTW, I intend to move existing parsing these out of the arch code. > Please don't add more DT handling to arch/ unless it is *really* arch > specific. I'd assume that the next arch to add kexec support will use > these bindings instead of the powerpc way.
So do you expect all the fdt-related stuff in my current implementation for arm64 to be put into libfdt, or at least drivers/of, from the beginning? I'm not sure how arch-specific the properties here are. For instance, it is only arm64 that uses "linux,usable-memory-range" right now but if some other arch follows, it is no more arch-specific. # I remember that you didn't like this property :) > > 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? > > Submit patches to upstream dtc and then we can pull it in. Ahead of that > you can add it to drivers/of/fdt.c (or maybe fdt_address.c because > that's really what this is dealing with). OK, I'm going to try to follow your suggestion. > libfdt has only recently gained the beginnings of address handling. > > > > > 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; > > I intend to make dt_root_*_cells private, so don't add another user > outside of drivers/of/. Once cells_size_fitted() moves to drivers/of, there will be no users. > > > + > > > + 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) > > I can't imagine this would happen. However, when this is moved to > drivers/of/ or dtc, these need to be u64 types to work on 32-bit. OK. > > > + /* 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; > > This should be a __be32 or fdt32 type. So should buf. OK for val32, but buf is a local pointer address. > > > + > > > + 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)); > > Look how of_read_number() is implemented. You should be able to do > something similar here looping and avoiding the if/else. Ah, excellent! > > > + } > > > +} > > > + > > > +static int fdt_setprop_range(void *fdt, int nodeoffset, const char *name, > > > + unsigned long addr, unsigned long size) > > A very generic sounding function, but really only works on addresses in > children of the root node. > > > > +{ > > > + 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); > > This can go on the stack instead (and would be required to to work in > libfdt). Well, I can't agree with you here since we are now in effort, as far as I correctly understand, of purging all the variable-sized arrays on a local stack out of the kernel code. Thank you for your review. -Takahiro AKASHI > > > + 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", > > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec