The commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate kernel that it is safe to modify the elfcorehdr
of kdump image loaded using kexec_load system call.
Similarly, add a new kexec flag, `KEXEC_UPDATE_FDT`, for another kdump
component named FDT (Flatten Device Tree). Architectures like PowerPC
need to update FDT kdump image component on CPU hotplug events. Kexec
tool passing `KEXEC_UPDATE_FDT` will be an indication to kernel that FDT
segment is not part of SHA calculation hence it is safe to update it.
With the `KEXEC_UPDATE_ELFCOREHDR` and `KEXEC_UPDATE_FDT` kexec flags,
crash hotplug support can be added to PowerPC for the kexec_load syscall
while maintaining the backward compatibility with older kexec tools that
do not have these newly introduced flags.
Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
Cc: Akhil Raj <lf32.dev@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Eric DeVolder <eric.devolder@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Cc: Laurent Dufour <laurent.dufour@xxxxxxxxxx>
Cc: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: kexec@xxxxxxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
---
include/linux/kexec.h | 6 ++++--
include/uapi/linux/kexec.h | 1 +
kernel/kexec.c | 2 ++
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0f6ea35879ee..bcedb7625b1f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -319,6 +319,7 @@ struct kimage {
#ifdef CONFIG_CRASH_HOTPLUG
/* If set, allow changes to elfcorehdr of kexec_load'd image */
unsigned int update_elfcorehdr:1;
+ unsigned int update_fdt:1;
#endif
#ifdef ARCH_HAS_KIMAGE_ARCH
@@ -396,9 +397,10 @@ bool kexec_load_permitted(int kexec_image_type);
/* List of defined/legal kexec flags */
#ifndef CONFIG_KEXEC_JUMP
-#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR)
+#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR | KEXEC_UPDATE_FDT)
#else
-#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR)
+#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR | \
+ KEXEC_UPDATE_FDT)
#endif
/* List of defined/legal kexec file flags */
diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h
index 01766dd839b0..3d5b3d757bed 100644
--- a/include/uapi/linux/kexec.h
+++ b/include/uapi/linux/kexec.h
@@ -13,6 +13,7 @@
#define KEXEC_ON_CRASH 0x00000001
#define KEXEC_PRESERVE_CONTEXT 0x00000002
#define KEXEC_UPDATE_ELFCOREHDR 0x00000004
+#define KEXEC_UPDATE_FDT 0x00000008
#define KEXEC_ARCH_MASK 0xffff0000
/*
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 8f35a5a42af8..97eb151cd931 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -132,6 +132,8 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
#ifdef CONFIG_CRASH_HOTPLUG
if (flags & KEXEC_UPDATE_ELFCOREHDR)
image->update_elfcorehdr = 1;
+ if (flags & KEXEC_UPDATE_FDT)
+ image->update_fdt = 1;
#endif
ret = machine_kexec_prepare(image);
--
2.41.0
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