James, On Tue, May 01, 2018 at 06:46:09PM +0100, James Morse wrote: > Hi Akashi, > > On 25/04/18 07:26, AKASHI Takahiro wrote: > > We need to prevent firmware-reserved memory regions, particularly EFI > > memory map as well as ACPI tables, from being corrupted by loading > > kernel/initrd (or other kexec buffers). We also want to support memory > > allocation in top-down manner in addition to default bottom-up. > > So let's have arm64 specific arch_kexec_walk_mem() which will search > > for available memory ranges in usable memblock list, > > i.e. !NOMAP & !reserved, > > > instead of system resource tree. > > Didn't we try to fix the system-resource-tree in order to fix regular-kexec to > be safe in the EFI-memory-map/ACPI-tables case? > > It would be good to avoid having two ways of doing this, and I would like to > avoid having extra arch code... I know what you mean. /proc/iomem or system resource is, in my opinion, not the best place to describe memory usage of kernel but rather to describe *physical* hardware layout. As we are still discussing about "reserved" memory, I don't want to depend on it. Along with memblock list, we will have more accurate control over memory usage. > > > diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c > > new file mode 100644 > > index 000000000000..f9ebf54ca247 > > --- /dev/null > > +++ b/arch/arm64/kernel/machine_kexec_file.c > > @@ -0,0 +1,57 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * kexec_file for arm64 > > + * > > + * Copyright (C) 2018 Linaro Limited > > + * Author: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> > > + * > > > + * Most code is derived from arm64 port of kexec-tools > > How does kexec-tools walk memblock? Will remove this comment from this patch. Obviously, this comment is for the rest of the code which will be added to succeeding patches (patch #5 and #7). > > > + */ > > + > > +#define pr_fmt(fmt) "kexec_file: " fmt > > + > > +#include <linux/ioport.h> > > +#include <linux/kernel.h> > > +#include <linux/kexec.h> > > +#include <linux/memblock.h> > > + > > +int arch_kexec_walk_mem(struct kexec_buf *kbuf, > > + int (*func)(struct resource *, void *)) > > +{ > > + phys_addr_t start, end; > > + struct resource res; > > + u64 i; > > + int ret = 0; > > + > > + if (kbuf->image->type == KEXEC_TYPE_CRASH) > > + return func(&crashk_res, kbuf); > > + > > + if (kbuf->top_down) > > + for_each_mem_range_rev(i, &memblock.memory, &memblock.reserved, > > + NUMA_NO_NODE, MEMBLOCK_NONE, > > + &start, &end, NULL) { > > for_each_free_mem_range_reverse() is a more readable version of this helper. OK. I used to use my own limited list of reserved memory instead of memblock.reserved here to exclude verbose ranges. > > + if (!memblock_is_map_memory(start)) > > + continue; > > Passing MEMBLOCK_NONE means this walk will never find MEMBLOCK_NOMAP memory. Sure, I confirmed it. > > > + res.start = start; > > + res.end = end; > > + ret = func(&res, kbuf); > > + if (ret) > > + break; > > + } > > + else > > + for_each_mem_range(i, &memblock.memory, &memblock.reserved, > > + NUMA_NO_NODE, MEMBLOCK_NONE, > > + &start, &end, NULL) { > > for_each_free_mem_range()? OK. > > + if (!memblock_is_map_memory(start)) > > + continue; > > + > > + res.start = start; > > + res.end = end; > > + ret = func(&res, kbuf); > > + if (ret) > > + break; > > + } > > + > > + return ret; > > +} > > > > With these changes, what we have is almost: > arch/powerpc/kernel/machine_kexec_file_64.c::arch_kexec_walk_mem() ! > (the difference being powerpc doesn't yet support crash-kernels here) > > If the argument is walking memblock gives a better answer than the stringy > walk_system_ram_res() thing, is there any mileage in moving this code into > kexec_file.c, and using it if !IS_ENABLED(CONFIG_ARCH_DISCARD_MEMBLOCK)? > > This would save arm64/powerpc having near-identical implementations. > 32bit arm keeps memblock if it has kexec, so it may be useful there too if > kexec_file_load() support is added. Thanks. I've forgot ppc. -Takahiro AKASHI > > Thanks, > > James _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec