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charset=us-ascii; format=flowed Content-Disposition: inline On Thu, Jan 01, 2026 at 08:36:09PM +0530, Sourabh Jain wrote: > > >On 26/12/25 19:36, Coiby Xu wrote: >>Based on the CONFIG_CRASH_DM_CRYPT feature, this patch adds >>LUKS-encrypted device dump target support to PowerPC by addressing two >>challenges [1], >> - Kdump kernel may not be able to decrypt the LUKS partition. For some >> machines, a system administrator may not have a chance to enter the >> password to decrypt the device in kdump initramfs after the 1st kernel >> crashes >> >> - LUKS2 by default use the memory-hard Argon2 key derivation function >> which is quite memory-consuming compared to the limited memory reserved >> for kdump. >> >>1st kernel will build up the kernel command parameter dmcryptkeys as >>similar to elfcorehdr to pass the memory address of the stored info of >>dm-crypt keys to the kdump kernel. >> >>[1] https://lore.kernel.org/all/20250502011246.99238-1-coxu@redhat.com/ >> >>Cc: Thomas Staudt >>Cc: Arnaud Lefebvre >>Cc: Baoquan he >>Cc: Dave Young >>Cc: Kairui Song >>Cc: Pingfan Liu >>Cc: Andrew Morton >>Signed-off-by: Coiby Xu >>--- >> arch/powerpc/include/asm/kexec.h | 3 ++- >> arch/powerpc/kexec/elf_64.c | 26 +++++++++++++++++++++++++- >> arch/powerpc/kexec/file_load.c | 19 +++++++++++-------- >> 3 files changed, 38 insertions(+), 10 deletions(-) >> >>diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h >>index bd4a6c42a5f3..f3d098d543b4 100644 >>--- a/arch/powerpc/include/asm/kexec.h >>+++ b/arch/powerpc/include/asm/kexec.h >>@@ -80,7 +80,8 @@ struct kimage_arch { >> }; >> char *setup_kdump_cmdline(struct kimage *image, char *cmdline, >>- unsigned long cmdline_len); >>+ unsigned long cmdline_len, >>+ char *name, unsigned long addr); >> int setup_purgatory(struct kimage *image, const void *slave_code, >> const void *fdt, unsigned long kernel_load_addr, >> unsigned long fdt_load_addr); >>diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c >>index 5d6d616404cf..57cb3361d91b 100644 >>--- a/arch/powerpc/kexec/elf_64.c >>+++ b/arch/powerpc/kexec/elf_64.c >>@@ -81,13 +81,37 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, >> /* Setup cmdline for kdump kernel case */ >> modified_cmdline = setup_kdump_cmdline(image, cmdline, >>- cmdline_len); >>+ cmdline_len, >>+ "elfcorehdr", >>+ image->elf_load_addr); >> if (!modified_cmdline) { >> pr_err("Setting up cmdline for kdump kernel failed\n"); >> ret = -EINVAL; >> goto out; >> } >> cmdline = modified_cmdline; >>+ cmdline_len = strlen(cmdline) + 1; >>+ >>+ ret = crash_load_dm_crypt_keys(image); >>+ if (ret == -ENOENT) { >>+ kexec_dprintk("No dm crypt key to load\n"); >>+ } else if (ret) { >>+ pr_err("Failed to load dm crypt keys\n"); >>+ return ERR_PTR(ret); >>+ } >>+ >>+ if (image->dm_crypt_keys_addr != 0) { >>+ modified_cmdline = setup_kdump_cmdline(image, cmdline, >>+ cmdline_len, >>+ "dmcryptkeys", >>+ image->dm_crypt_keys_addr); >>+ if (!modified_cmdline) { >>+ pr_err("Setting up cmdline for kdump kernel failed\n"); >>+ ret = -EINVAL; >>+ goto out; >>+ } >>+ cmdline = modified_cmdline; >>+ } >> } >> if (initrd != NULL) { >>diff --git a/arch/powerpc/kexec/file_load.c b/arch/powerpc/kexec/file_load.c >>index 4284f76cbef5..e1c08050286d 100644 >>--- a/arch/powerpc/kexec/file_load.c >>+++ b/arch/powerpc/kexec/file_load.c >>@@ -23,38 +23,41 @@ >> #define SLAVE_CODE_SIZE 256 /* First 0x100 bytes */ >> /** >>- * setup_kdump_cmdline - Prepend "elfcorehdr= " to command line >>+ * setup_kdump_cmdline - Prepend "= " to command line >> * of kdump kernel for exporting the core. >> * @image: Kexec image >> * @cmdline: Command line parameters to update. >> * @cmdline_len: Length of the cmdline parameters. >>+ * @name: Name e.g elfcorehdr. >>+ * @addr: Memory address. >> * >> * kdump segment must be setup before calling this function. >> * >> * Returns new cmdline buffer for kdump kernel on success, NULL otherwise. >> */ >> char *setup_kdump_cmdline(struct kimage *image, char *cmdline, >>- unsigned long cmdline_len) >>+ unsigned long cmdline_len, >>+ char *name, unsigned long addr) >> { >>- int elfcorehdr_strlen; >>+ unsigned long parameter_len; >> char *cmdline_ptr; >> cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL); >> if (!cmdline_ptr) >> return NULL; >>- elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ", >>- image->elf_load_addr); >>+ parameter_len = sprintf(cmdline_ptr, "%s=0x%lx ", name, addr); >>- if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) { >>- pr_err("Appending elfcorehdr= exceeds cmdline size\n"); >>+ if (parameter_len + cmdline_len > COMMAND_LINE_SIZE) { >>+ pr_err("Appending %s= exceeds cmdline size\n", name); >> kfree(cmdline_ptr); >> return NULL; >> } >>- memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len); >>+ memcpy(cmdline_ptr + parameter_len, cmdline, cmdline_len); >> // Ensure it's nul terminated >> cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0'; >>+ kfree(cmdline); > >When setup_kdump_cmdline() is called for elfcorehdr, cmdline holds the >same pointer as image->cmdline_buf. Freeing it here may therefore >cause issues, right? Yes, you are right, I'll drop the above kfree in next version. > >Currently, image->cmdline_buf is not used after calling the >architecture-specific load function (elf64_load on powerpc). >However, kimage_file_post_load_cleanup() later calls kfree() on >the same address. I missed kimage_file_post_load_cleanup. Thanks for pointing it out! -- Best regards, Coiby