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Patch series "kexec_file: print out debugging message if required", v4. Currently, specifying '-d' on kexec command will print a lot of debugging informationabout kexec/kdump loading with kexec_load interface. However, kexec_file_load prints nothing even though '-d' is specified. It's very inconvenient to debug or analyze the kexec/kdump loading when something wrong happened with kexec/kdump itself or develper want to check the kexec/kdump loading. In this patchset, a kexec_file flag is KEXEC_FILE_DEBUG added and checked in code. If it's passed in, debugging message of kexec_file code will be printed out and can be seen from console and dmesg. Otherwise, the debugging message is printed like beofre when pr_debug() is taken. Note: **** ===== 1) The code in kexec-tools utility also need be changed to support passing KEXEC_FILE_DEBUG to kernel when 'kexec -s -d' is specified. The patch link is here: ========= [PATCH] kexec_file: add kexec_file flag to support debug printing http://lists.infradead.org/pipermail/kexec/2023-November/028505.html 2) s390 also has kexec_file code, while I am not sure what debugging information is necessary. So leave it to s390 developer. Test: **** ==== Testing was done in v1 on x86_64 and arm64. For v4, tested on x86_64 again. And on x86_64, the printed messages look like below: -------------------------------------------------------------- kexec measurement buffer for the loaded kernel at 0x207fffe000. Loaded purgatory at 0x207fff9000 Loaded boot_param, command line and misc at 0x207fff3000 bufsz=0x1180 memsz=0x1180 Loaded 64bit kernel at 0x207c000000 bufsz=0xc88200 memsz=0x3c4a000 Loaded initrd at 0x2079e79000 bufsz=0x2186280 memsz=0x2186280 Final command line is: root=/dev/mapper/fedora_intel--knightslanding--lb--02-root ro rd.lvm.lv=fedora_intel-knightslanding-lb-02/root console=ttyS0,115200N81 crashkernel=256M E820 memmap: 0000000000000000-000000000009a3ff (1) 000000000009a400-000000000009ffff (2) 00000000000e0000-00000000000fffff (2) 0000000000100000-000000006ff83fff (1) 000000006ff84000-000000007ac50fff (2) ...... 000000207fff6150-000000207fff615f (128) 000000207fff6160-000000207fff714f (1) 000000207fff7150-000000207fff715f (128) 000000207fff7160-000000207fff814f (1) 000000207fff8150-000000207fff815f (128) 000000207fff8160-000000207fffffff (1) nr_segments = 5 segment[0]: buf=0x000000004e5ece74 bufsz=0x211 mem=0x207fffe000 memsz=0x1000 segment[1]: buf=0x000000009e871498 bufsz=0x4000 mem=0x207fff9000 memsz=0x5000 segment[2]: buf=0x00000000d879f1fe bufsz=0x1180 mem=0x207fff3000 memsz=0x2000 segment[3]: buf=0x000000001101cd86 bufsz=0xc88200 mem=0x207c000000 memsz=0x3c4a000 segment[4]: buf=0x00000000c6e38ac7 bufsz=0x2186280 mem=0x2079e79000 memsz=0x2187000 kexec_file_load: type:0, start:0x207fff91a0 head:0x109e004002 flags:0x8 --------------------------------------------------------------------------- This patch (of 7): When specifying 'kexec -c -d', kexec_load interface will print loading information, e.g the regions where kernel/initrd/purgatory/cmdline are put, the memmap passed to 2nd kernel taken as system RAM ranges, and printing all contents of struct kexec_segment, etc. These are very helpful for analyzing or positioning what's happening when kexec/kdump itself failed. The debugging printing for kexec_load interface is made in user space utility kexec-tools. Whereas, with kexec_file_load interface, 'kexec -s -d' print nothing. Because kexec_file code is mostly implemented in kernel space, and the debugging printing functionality is missed. It's not convenient when debugging kexec/kdump loading and jumping with kexec_file_load interface. Now add KEXEC_FILE_DEBUG to kexec_file flag to control the debugging message printing. And add global variable kexec_file_dbg_print and macro kexec_dprintk() to facilitate the printing. This is a preparation, later kexec_dprintk() will be used to replace the existing pr_debug(). Once 'kexec -s -d' is specified, it will print out kexec/kdump loading information. If '-d' is not specified, it regresses to pr_debug(). Link: https://lkml.kernel.org/r/20231213055747.61826-1-bhe@redhat.com Link: https://lkml.kernel.org/r/20231213055747.61826-2-bhe@redhat.com Signed-off-by: Baoquan He <bhe@redhat.com> Cc: Conor Dooley <conor@kernel.org> Cc: Joe Perches <joe@perches.com> Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPILINUX_KEXEC_H
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#define _UAPILINUX_KEXEC_H
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/* kexec system call - It loads the new kernel to boot into.
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* kexec does not sync, or unmount filesystems so if you need
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* that to happen you need to do that yourself.
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*/
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#include <linux/types.h>
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/* kexec flags for different usage scenarios */
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#define KEXEC_ON_CRASH 0x00000001
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#define KEXEC_PRESERVE_CONTEXT 0x00000002
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#define KEXEC_UPDATE_ELFCOREHDR 0x00000004
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#define KEXEC_ARCH_MASK 0xffff0000
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/*
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* Kexec file load interface flags.
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* KEXEC_FILE_UNLOAD : Unload already loaded kexec/kdump image.
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* KEXEC_FILE_ON_CRASH : Load/unload operation belongs to kdump image.
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* KEXEC_FILE_NO_INITRAMFS : No initramfs is being loaded. Ignore the initrd
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* fd field.
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*/
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#define KEXEC_FILE_UNLOAD 0x00000001
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#define KEXEC_FILE_ON_CRASH 0x00000002
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#define KEXEC_FILE_NO_INITRAMFS 0x00000004
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#define KEXEC_FILE_DEBUG 0x00000008
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/* These values match the ELF architecture values.
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* Unless there is a good reason that should continue to be the case.
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*/
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#define KEXEC_ARCH_DEFAULT ( 0 << 16)
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#define KEXEC_ARCH_386 ( 3 << 16)
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#define KEXEC_ARCH_68K ( 4 << 16)
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#define KEXEC_ARCH_PARISC (15 << 16)
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#define KEXEC_ARCH_X86_64 (62 << 16)
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#define KEXEC_ARCH_PPC (20 << 16)
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#define KEXEC_ARCH_PPC64 (21 << 16)
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#define KEXEC_ARCH_IA_64 (50 << 16)
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#define KEXEC_ARCH_ARM (40 << 16)
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#define KEXEC_ARCH_S390 (22 << 16)
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#define KEXEC_ARCH_SH (42 << 16)
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#define KEXEC_ARCH_MIPS_LE (10 << 16)
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#define KEXEC_ARCH_MIPS ( 8 << 16)
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#define KEXEC_ARCH_AARCH64 (183 << 16)
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#define KEXEC_ARCH_RISCV (243 << 16)
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#define KEXEC_ARCH_LOONGARCH (258 << 16)
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/* The artificial cap on the number of segments passed to kexec_load. */
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#define KEXEC_SEGMENT_MAX 16
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#ifndef __KERNEL__
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/*
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* This structure is used to hold the arguments that are used when
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* loading kernel binaries.
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*/
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struct kexec_segment {
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const void *buf;
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__kernel_size_t bufsz;
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const void *mem;
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__kernel_size_t memsz;
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};
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#endif /* __KERNEL__ */
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#endif /* _UAPILINUX_KEXEC_H */
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