From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Fri, 26 Aug 2016 15:22:03 +0900 Subject: [PATCH v24 5/9] arm64: kdump: add kdump support In-Reply-To: References: <20160809015248.28414-2-takahiro.akashi@linaro.org> <20160809015615.28527-1-takahiro.akashi@linaro.org> <20160809015615.28527-3-takahiro.akashi@linaro.org> Message-ID: <20160826062201.GO20080@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Aug 24, 2016 at 04:44:09PM +0200, Ard Biesheuvel wrote: > On 9 August 2016 at 03:56, AKASHI Takahiro wrote: > > On crash dump kernel, all the information about primary kernel's system > > memory (core image) is available in elf core header. > > The primary kernel will set aside this header with reserve_elfcorehdr() > > at boot time and inform crash dump kernel of its location via a new > > device-tree property, "linux,elfcorehdr". > > > > Please note that all other architectures use traditional "elfcorehdr=" > > kernel parameter for this purpose. > > > > Then crash dump kernel will access the primary kernel's memory with > > copy_oldmem_page(), which reads one page by ioremap'ing it since it does > > not reside in linear mapping on crash dump kernel. > > > > We also need our own elfcorehdr_read() here since the header is placed > > within crash dump kernel's usable memory. > > > > Signed-off-by: AKASHI Takahiro > > --- > > arch/arm64/Kconfig | 11 +++++++ > > arch/arm64/kernel/Makefile | 1 + > > arch/arm64/kernel/crash_dump.c | 71 ++++++++++++++++++++++++++++++++++++++++++ > > arch/arm64/mm/init.c | 54 ++++++++++++++++++++++++++++++++ > > 4 files changed, 137 insertions(+) > > create mode 100644 arch/arm64/kernel/crash_dump.c > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 69c8787..9ede54b 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -682,6 +682,17 @@ config KEXEC > > but it is independent of the system firmware. And like a reboot > > you can start any kernel with it, not just Linux. > > > > +config CRASH_DUMP > > + bool "Build kdump crash kernel" > > + help > > + Generate crash dump after being started by kexec. This should > > + be normally only set in special crash dump kernels which are > > + loaded in the main kernel with kexec-tools into a specially > > + reserved region and then later executed after a crash by > > + kdump/kexec. > > + > > + For more details see Documentation/kdump/kdump.txt > > + > > config XEN_DOM0 > > def_bool y > > depends on XEN > > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > > index 14f7b65..f1cbfc8 100644 > > --- a/arch/arm64/kernel/Makefile > > +++ b/arch/arm64/kernel/Makefile > > @@ -48,6 +48,7 @@ arm64-obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o > > arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o > > arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o \ > > cpu-reset.o > > +arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o > > > > obj-y += $(arm64-obj-y) vdso/ probes/ > > obj-m += $(arm64-obj-m) > > diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c > > new file mode 100644 > > index 0000000..2dc54d1 > > --- /dev/null > > +++ b/arch/arm64/kernel/crash_dump.c > > @@ -0,0 +1,71 @@ > > +/* > > + * Routines for doing kexec-based kdump > > + * > > + * Copyright (C) 2014 Linaro Limited > > + * Author: AKASHI Takahiro > > + * > > + * This program is free software; you can redistribute it and/or modify > > + * it under the terms of the GNU General Public License version 2 as > > + * published by the Free Software Foundation. > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +/** > > + * copy_oldmem_page() - copy one page from old kernel memory > > + * @pfn: page frame number to be copied > > + * @buf: buffer where the copied page is placed > > + * @csize: number of bytes to copy > > + * @offset: offset in bytes into the page > > + * @userbuf: if set, @buf is in a user address space > > + * > > + * This function copies one page from old kernel memory into buffer pointed by > > + * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes > > + * copied or negative error in case of failure. > > + */ > > +ssize_t copy_oldmem_page(unsigned long pfn, char *buf, > > + size_t csize, unsigned long offset, > > + int userbuf) > > +{ > > + void *vaddr; > > + > > + if (!csize) > > + return 0; > > + > > + vaddr = ioremap_cache(__pfn_to_phys(pfn), PAGE_SIZE); > > Could we please use memremap() here? > > > + if (!vaddr) > > + return -ENOMEM; > > + > > + if (userbuf) { > > + if (copy_to_user(buf, vaddr + offset, csize)) { > > + iounmap(vaddr); > > + return -EFAULT; > > + } > > + } else { > > + memcpy(buf, vaddr + offset, csize); > > + } > > + > > + iounmap(vaddr); > > ... and memunmap here? > > ioremap_cache() is not very well defined, and memremap() has been > introduced specifically to replace it, so I think we should use it in > new code. Sure. I will use memremap(MEMREMAP_WB) instead. Thanks, -Takahiro AKASHI > Thanks, > Ard. > > > > + > > + return csize; > > +} > > + > > +/** > > + * elfcorehdr_read - read from ELF core header > > + * @buf: buffer where the data is placed > > + * @csize: number of bytes to read > > + * @ppos: address in the memory > > + * > > + * This function reads @count bytes from elf core header which exists > > + * on crash dump kernel's memory. > > + */ > > +ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) > > +{ > > + memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); > > + return count; > > +} > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > index e3771c4..bba1e39 100644 > > --- a/arch/arm64/mm/init.c > > +++ b/arch/arm64/mm/init.c > > @@ -36,6 +36,7 @@ > > #include > > #include > > #include > > +#include > > > > #include > > #include > > @@ -186,6 +187,57 @@ static void __init reserve_crashkernel(void) > > } > > #endif /* CONFIG_KEXEC_CORE */ > > > > +#ifdef CONFIG_CRASH_DUMP > > +static int __init early_init_dt_scan_elfcorehdr(unsigned long node, > > + const char *uname, int depth, void *data) > > +{ > > + const __be32 *reg; > > + int len; > > + > > + if (depth != 1 || strcmp(uname, "chosen") != 0) > > + return 0; > > + > > + reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len); > > + if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells))) > > + return 1; > > + > > + elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, ®); > > + elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, ®); > > + > > + return 1; > > +} > > + > > +/* > > + * reserve_elfcorehdr() - reserves memory for elf core header > > + * > > + * This function reserves elf core header given in "elfcorehdr=" kernel > > + * command line parameter. This region contains all the information about > > + * primary kernel's core image and is used by a dump capture kernel to > > + * access the system memory on primary kernel. > > + */ > > +static void __init reserve_elfcorehdr(void) > > +{ > > + of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL); > > + > > + if (!elfcorehdr_size) > > + return; > > + > > + if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) { > > + pr_warn("elfcorehdr is overlapped\n"); > > + return; > > + } > > + > > + memblock_reserve(elfcorehdr_addr, elfcorehdr_size); > > + > > + pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n", > > + elfcorehdr_size >> 10, elfcorehdr_addr); > > +} > > +#else > > +static void __init reserve_elfcorehdr(void) > > +{ > > + ; > > +} > > +#endif /* CONFIG_CRASH_DUMP */ > > /* > > * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It > > * currently assumes that for memory starting above 4G, 32-bit devices will > > @@ -444,6 +496,8 @@ void __init arm64_memblock_init(void) > > > > reserve_crashkernel(); > > > > + reserve_elfcorehdr(); > > + > > dma_contiguous_reserve(arm64_dma_phys_limit); > > > > memblock_allow_resize(); > > -- > > 2.9.0 > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel at lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel