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 --------------------------------------------------------------------------- History: ========= v3->v4: - Add the explanation about why kexec_dprintk() need be introduced to replace pr_debug() in log of ARCH patch, suggested by Conor. - Mentioned why pr_notice() need be replaced with kexec_dprintk() in function elf_kexec_load() of risc-v, Suggested by Conor. - Change breaking one message line into two back to one line, pointed out by Joe. v2->v3: - Adjust all the indentation of continuation line to the open parenthesis for all kexec_dprintk() call sites. Thank Joe to point this out. - Fix the LKP report that macro kexec_dprintk() is invalid when CONFIG_KEXEC=Y, CONFIG_KEXEC_FILE=n, CONFIG_CRASH_DUMP=y. v1->v2: - Take the new format of kexec_dprintk() suggested by Joe which can reduce kernel text size. - Fix building error of patch 2 in kernel/crash_core.c reported by LKP. - Fix building warning on arm64 in patch 4 reported by LKP. Baoquan He (7): kexec_file: add kexec_file flag to control debug printing kexec_file: print out debugging message if required kexec_file, x86: print out debugging message if required kexec_file, arm64: print out debugging message if required kexec_file, ricv: print out debugging message if required kexec_file, power: print out debugging message if required kexec_file, parisc: print out debugging message if required arch/arm64/kernel/kexec_image.c | 6 +++--- arch/arm64/kernel/machine_kexec.c | 26 ++++++-------------------- arch/arm64/kernel/machine_kexec_file.c | 12 ++++++------ arch/parisc/kernel/kexec_file.c | 8 ++++---- arch/powerpc/kexec/elf_64.c | 8 ++++---- arch/powerpc/kexec/file_load_64.c | 18 +++++++++--------- arch/riscv/kernel/elf_kexec.c | 11 ++++++----- arch/riscv/kernel/machine_kexec.c | 26 -------------------------- arch/x86/kernel/crash.c | 4 ++-- arch/x86/kernel/kexec-bzimage64.c | 23 ++++++++++++++--------- include/linux/kexec.h | 9 ++++++++- include/uapi/linux/kexec.h | 1 + kernel/crash_core.c | 8 +++++--- kernel/kexec_core.c | 2 ++ kernel/kexec_file.c | 14 +++++++++++--- security/integrity/ima/ima_kexec.c | 4 ++-- 16 files changed, 83 insertions(+), 97 deletions(-) -- 2.41.0
