From: Nick Kossifidis <mick@ics.forth.gr> To: linux-riscv@lists.infradead.org, palmer@dabbelt.com Cc: paul.walmsley@sifive.com, linux-kernel@vger.kernel.org, Nick Kossifidis <mickflemm@gmail.com>, Nick Kossifidis <mick@ics.forth.gr> Subject: [PATCH v3 5/5] RISC-V: Add crash kernel support Date: Mon, 5 Apr 2021 11:57:12 +0300 [thread overview] Message-ID: <20210405085712.1953848-6-mick@ics.forth.gr> (raw) In-Reply-To: <20210405085712.1953848-1-mick@ics.forth.gr> From: Nick Kossifidis <mickflemm@gmail.com> This patch allows Linux to act as a crash kernel for use with kdump. Userspace will let the crash kernel know about the memory region it can use through linux,usable-memory property on the /memory node (overriding its reg property), and about the memory region where the elf core header of the previous kernel is saved, through a reserved-memory node with a compatible string of "linux,elfcorehdr". This approach is the least invasive and re-uses functionality already present. I tested this on riscv64 qemu and it works as expected, you may test it by retrieving the dmesg of the previous kernel through /proc/vmcore, using the vmcore-dmesg utility from kexec-tools. v3: * Rebase v2: * Use linux,usable-memory on /memory instead of a new binding * Use a reserved-memory node for ELF core header Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> --- arch/riscv/Kconfig | 10 ++++++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/crash_dump.c | 46 ++++++++++++++++++++++++++++++++++ arch/riscv/kernel/setup.c | 12 +++++++++ arch/riscv/mm/init.c | 33 ++++++++++++++++++++++++ 5 files changed, 102 insertions(+) create mode 100644 arch/riscv/kernel/crash_dump.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 3716262ef..553c2dced 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -403,6 +403,16 @@ config KEXEC The name comes from the similarity to the exec system call. +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/admin-guide/kdump/kdump.rst endmenu diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 07f676ad3..bd66d2ce0 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -59,6 +59,7 @@ endif obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o obj-$(CONFIG_KGDB) += kgdb.o obj-${CONFIG_KEXEC} += kexec_relocate.o crash_save_regs.o machine_kexec.o +obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c new file mode 100644 index 000000000..86cc0ada5 --- /dev/null +++ b/arch/riscv/kernel/crash_dump.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This code comes from arch/arm64/kernel/crash_dump.c + * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org> + * Copyright (C) 2017 Linaro Limited + */ + +#include <linux/crash_dump.h> +#include <linux/io.h> + +/** + * 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 = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB); + if (!vaddr) + return -ENOMEM; + + if (userbuf) { + if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { + memunmap(vaddr); + return -EFAULT; + } + } else + memcpy(buf, vaddr + offset, csize); + + memunmap(vaddr); + return csize; +} diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 31866dce9..ff398a3d8 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -66,6 +66,9 @@ static struct resource code_res = { .name = "Kernel code", }; static struct resource data_res = { .name = "Kernel data", }; static struct resource rodata_res = { .name = "Kernel rodata", }; static struct resource bss_res = { .name = "Kernel bss", }; +#ifdef CONFIG_CRASH_DUMP +static struct resource elfcorehdr_res = { .name = "ELF Core hdr", }; +#endif static int __init add_resource(struct resource *parent, struct resource *res) @@ -169,6 +172,15 @@ static void __init init_resources(void) } #endif +#ifdef CONFIG_CRASH_DUMP + if (elfcorehdr_size > 0) { + elfcorehdr_res.start = elfcorehdr_addr; + elfcorehdr_res.end = elfcorehdr_addr + elfcorehdr_size - 1; + elfcorehdr_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; + add_resource(&iomem_resource, &elfcorehdr_res); + } +#endif + for_each_reserved_mem_region(region) { res = &mem_res[res_idx--]; diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index e71b35cec..f66011816 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -13,6 +13,7 @@ #include <linux/swap.h> #include <linux/sizes.h> #include <linux/of_fdt.h> +#include <linux/of_reserved_mem.h> #include <linux/libfdt.h> #include <linux/set_memory.h> #include <linux/dma-map-ops.h> @@ -606,6 +607,18 @@ static void __init reserve_crashkernel(void) int ret = 0; + /* + * Don't reserve a region for a crash kernel on a crash kernel + * since it doesn't make much sense and we have limited memory + * resources. + */ +#ifdef CONFIG_CRASH_DUMP + if (is_kdump_kernel()) { + pr_info("crashkernel: ignoring reservation request\n"); + return; + } +#endif + ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), &crash_size, &crash_base); if (ret || !crash_size) @@ -660,6 +673,26 @@ static void __init reserve_crashkernel(void) } #endif /* CONFIG_KEXEC_CORE */ +#ifdef CONFIG_CRASH_DUMP +/* + * We keep track of the ELF core header of the crashed + * kernel with a reserved-memory region with compatible + * string "linux,elfcorehdr". Here we register a callback + * to populate elfcorehdr_addr/size when this region is + * present. Note that this region will be marked as + * reserved once we call early_init_fdt_scan_reserved_mem() + * later on. + */ +static int elfcore_hdr_setup(struct reserved_mem *rmem) +{ + elfcorehdr_addr = rmem->base; + elfcorehdr_size = rmem->size; + return 0; +} + +RESERVEDMEM_OF_DECLARE(elfcorehdr, "linux,elfcorehdr", elfcore_hdr_setup); +#endif + void __init paging_init(void) { setup_vm_final(); -- 2.26.2
WARNING: multiple messages have this Message-ID (diff)
From: Nick Kossifidis <mick@ics.forth.gr> To: linux-riscv@lists.infradead.org, palmer@dabbelt.com Cc: paul.walmsley@sifive.com, linux-kernel@vger.kernel.org, Nick Kossifidis <mickflemm@gmail.com>, Nick Kossifidis <mick@ics.forth.gr> Subject: [PATCH v3 5/5] RISC-V: Add crash kernel support Date: Mon, 5 Apr 2021 11:57:12 +0300 [thread overview] Message-ID: <20210405085712.1953848-6-mick@ics.forth.gr> (raw) In-Reply-To: <20210405085712.1953848-1-mick@ics.forth.gr> From: Nick Kossifidis <mickflemm@gmail.com> This patch allows Linux to act as a crash kernel for use with kdump. Userspace will let the crash kernel know about the memory region it can use through linux,usable-memory property on the /memory node (overriding its reg property), and about the memory region where the elf core header of the previous kernel is saved, through a reserved-memory node with a compatible string of "linux,elfcorehdr". This approach is the least invasive and re-uses functionality already present. I tested this on riscv64 qemu and it works as expected, you may test it by retrieving the dmesg of the previous kernel through /proc/vmcore, using the vmcore-dmesg utility from kexec-tools. v3: * Rebase v2: * Use linux,usable-memory on /memory instead of a new binding * Use a reserved-memory node for ELF core header Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> --- arch/riscv/Kconfig | 10 ++++++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/crash_dump.c | 46 ++++++++++++++++++++++++++++++++++ arch/riscv/kernel/setup.c | 12 +++++++++ arch/riscv/mm/init.c | 33 ++++++++++++++++++++++++ 5 files changed, 102 insertions(+) create mode 100644 arch/riscv/kernel/crash_dump.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 3716262ef..553c2dced 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -403,6 +403,16 @@ config KEXEC The name comes from the similarity to the exec system call. +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/admin-guide/kdump/kdump.rst endmenu diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 07f676ad3..bd66d2ce0 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -59,6 +59,7 @@ endif obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o obj-$(CONFIG_KGDB) += kgdb.o obj-${CONFIG_KEXEC} += kexec_relocate.o crash_save_regs.o machine_kexec.o +obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c new file mode 100644 index 000000000..86cc0ada5 --- /dev/null +++ b/arch/riscv/kernel/crash_dump.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This code comes from arch/arm64/kernel/crash_dump.c + * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org> + * Copyright (C) 2017 Linaro Limited + */ + +#include <linux/crash_dump.h> +#include <linux/io.h> + +/** + * 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 = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB); + if (!vaddr) + return -ENOMEM; + + if (userbuf) { + if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { + memunmap(vaddr); + return -EFAULT; + } + } else + memcpy(buf, vaddr + offset, csize); + + memunmap(vaddr); + return csize; +} diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 31866dce9..ff398a3d8 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -66,6 +66,9 @@ static struct resource code_res = { .name = "Kernel code", }; static struct resource data_res = { .name = "Kernel data", }; static struct resource rodata_res = { .name = "Kernel rodata", }; static struct resource bss_res = { .name = "Kernel bss", }; +#ifdef CONFIG_CRASH_DUMP +static struct resource elfcorehdr_res = { .name = "ELF Core hdr", }; +#endif static int __init add_resource(struct resource *parent, struct resource *res) @@ -169,6 +172,15 @@ static void __init init_resources(void) } #endif +#ifdef CONFIG_CRASH_DUMP + if (elfcorehdr_size > 0) { + elfcorehdr_res.start = elfcorehdr_addr; + elfcorehdr_res.end = elfcorehdr_addr + elfcorehdr_size - 1; + elfcorehdr_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; + add_resource(&iomem_resource, &elfcorehdr_res); + } +#endif + for_each_reserved_mem_region(region) { res = &mem_res[res_idx--]; diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index e71b35cec..f66011816 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -13,6 +13,7 @@ #include <linux/swap.h> #include <linux/sizes.h> #include <linux/of_fdt.h> +#include <linux/of_reserved_mem.h> #include <linux/libfdt.h> #include <linux/set_memory.h> #include <linux/dma-map-ops.h> @@ -606,6 +607,18 @@ static void __init reserve_crashkernel(void) int ret = 0; + /* + * Don't reserve a region for a crash kernel on a crash kernel + * since it doesn't make much sense and we have limited memory + * resources. + */ +#ifdef CONFIG_CRASH_DUMP + if (is_kdump_kernel()) { + pr_info("crashkernel: ignoring reservation request\n"); + return; + } +#endif + ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), &crash_size, &crash_base); if (ret || !crash_size) @@ -660,6 +673,26 @@ static void __init reserve_crashkernel(void) } #endif /* CONFIG_KEXEC_CORE */ +#ifdef CONFIG_CRASH_DUMP +/* + * We keep track of the ELF core header of the crashed + * kernel with a reserved-memory region with compatible + * string "linux,elfcorehdr". Here we register a callback + * to populate elfcorehdr_addr/size when this region is + * present. Note that this region will be marked as + * reserved once we call early_init_fdt_scan_reserved_mem() + * later on. + */ +static int elfcore_hdr_setup(struct reserved_mem *rmem) +{ + elfcorehdr_addr = rmem->base; + elfcorehdr_size = rmem->size; + return 0; +} + +RESERVEDMEM_OF_DECLARE(elfcorehdr, "linux,elfcorehdr", elfcore_hdr_setup); +#endif + void __init paging_init(void) { setup_vm_final(); -- 2.26.2 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2021-04-05 8:58 UTC|newest] Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-05 8:57 [PATCH v3 0/5] RISC-V: Add kexec/kdump support Nick Kossifidis 2021-04-05 8:57 ` Nick Kossifidis 2021-04-05 8:57 ` [PATCH v3 1/5] RISC-V: Add EM_RISCV to kexec UAPI header Nick Kossifidis 2021-04-05 8:57 ` Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-05 8:57 ` [PATCH v3 2/5] RISC-V: Add kexec support Nick Kossifidis 2021-04-05 8:57 ` Nick Kossifidis 2021-04-06 18:38 ` Alex Ghiti 2021-04-06 18:38 ` Alex Ghiti 2021-04-09 10:19 ` Nick Kossifidis 2021-04-09 10:19 ` Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-05 8:57 ` [PATCH v3 3/5] RISC-V: Improve init_resources Nick Kossifidis 2021-04-05 8:57 ` Nick Kossifidis 2021-04-06 7:19 ` Geert Uytterhoeven 2021-04-06 7:19 ` Geert Uytterhoeven 2021-04-06 8:11 ` Nick Kossifidis 2021-04-06 8:11 ` Nick Kossifidis 2021-04-06 8:22 ` Geert Uytterhoeven 2021-04-06 8:22 ` Geert Uytterhoeven 2021-04-09 10:11 ` Nick Kossifidis 2021-04-09 10:11 ` Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-05 8:57 ` [PATCH v3 4/5] RISC-V: Add kdump support Nick Kossifidis 2021-04-05 8:57 ` Nick Kossifidis 2021-04-06 18:36 ` Alex Ghiti 2021-04-06 18:36 ` Alex Ghiti 2021-04-09 10:21 ` Nick Kossifidis 2021-04-09 10:21 ` Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-05 8:57 ` Nick Kossifidis [this message] 2021-04-05 8:57 ` [PATCH v3 5/5] RISC-V: Add crash kernel support Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-07 7:45 ` [PATCH v3 0/5] RISC-V: Add kexec/kdump support Yixun Lan 2021-04-07 7:45 ` Yixun Lan 2021-04-07 16:29 ` Rob Herring 2021-04-07 16:29 ` Rob Herring 2021-04-09 10:02 ` Nick Kossifidis 2021-04-09 10:02 ` Nick Kossifidis 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:30 ` Palmer Dabbelt 2021-04-23 3:36 ` Nick Kossifidis 2021-04-23 3:36 ` Nick Kossifidis 2021-04-23 3:48 ` Palmer Dabbelt 2021-04-23 3:48 ` Palmer Dabbelt 2021-04-23 3:53 ` Nick Kossifidis 2021-04-23 3:53 ` Nick Kossifidis
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