Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
Hello Hari,
On 02/03/24 18:47, Hari Bathini wrote:
On 26/02/24 2:11 pm, Sourabh Jain wrote:
Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.
However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.
Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
the kernel, it indicates to the kernel that all the required kexec
segment is skipped from SHA calculation and it is safe to update kdump
image loaded using the kexec_load syscall.
While loading the kdump image using the kexec_load syscall, the
@update_elfcorehdr member of struct kimage is set if the kexec tool
sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
to determine whether it is safe to update elfcorehdr on hotplug events.
However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
flag, the kexec tool could mark all the required kexec segments on an
architecture as safe to update. So rename the @update_elfcorehdr to
@hotplug_support. If @hotplug_support is set, the kernel can safely
update all the required kexec segments of the kdump image during
CPU/Memory hotplug events.
Introduce an architecture-specific function to process kexec flags for
determining hotplug support. Set the @hotplug_support member of struct
kimage for both kexec_load and kexec_file_load system calls. This
simplifies kernel checks to identify hotplug support for the currently
loaded kdump image by just examining the value of @hotplug_support.
Couple of minor nits. See comments below.
Otherwise, looks good to me.
Acked-by: Hari Bathini
Thank you!
Signed-off-by: Sourabh Jain
Cc: Akhil Raj
Cc: Andrew Morton
Cc: Aneesh Kumar K.V
Cc: Baoquan He
Cc: Borislav Petkov (AMD)
Cc: Boris Ostrovsky
Cc: Christophe Leroy
Cc: Dave Hansen
Cc: Dave Young
Cc: David Hildenbrand
Cc: Eric DeVolder
Cc: Greg Kroah-Hartman
Cc: Hari Bathini
Cc: Laurent Dufour
Cc: Mahesh Salgaonkar
Cc: Michael Ellerman
Cc: Mimi Zohar
Cc: Naveen N Rao
Cc: Oscar Salvador
Cc: Thomas Gleixner
Cc: Valentin Schneider
Cc: Vivek Goyal
Cc: ke...@lists.infradead.org
Cc: x...@kernel.org
---
arch/x86/include/asm/kexec.h | 11 ++-
arch/x86/kernel/crash.c | 28 +---
drivers/base/cpu.c | 2 +-
drivers/base/memory.c | 2 +-
include/linux/crash_core.h | 13 ++---
include/linux/kexec.h | 11 +++
include/uapi/linux/kexec.h | 1 +
kernel/crash_core.c | 11 ---
kernel/kexec.c | 4 ++--
kernel/kexec_file.c | 5 +
10 files changed, 46 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index cb1320ebbc23..ae5482a2f0ca 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event
arch_crash_handle_hotplug_event
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void);
-#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void);
-#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
-#endif
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags);
+#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2a682fe86352..f06501445cd9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
-/* These functions provide the value for the sysfs crash_hotplug
nodes */
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void)
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags)
{
- return crash_check_update_elfcorehdr();
-}
-#endif
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void)
-{
- return crash_check_update_elfcorehdr();
-}
+#ifdef CONFIG_KEXEC_FILE
+ if (image->file_mode)
+ return 1;
#endif
+ /*
+ * Initially, crash
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
On 26/02/24 2:11 pm, Sourabh Jain wrote:
Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.
However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.
Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
the kernel, it indicates to the kernel that all the required kexec
segment is skipped from SHA calculation and it is safe to update kdump
image loaded using the kexec_load syscall.
While loading the kdump image using the kexec_load syscall, the
@update_elfcorehdr member of struct kimage is set if the kexec tool
sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
to determine whether it is safe to update elfcorehdr on hotplug events.
However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
flag, the kexec tool could mark all the required kexec segments on an
architecture as safe to update. So rename the @update_elfcorehdr to
@hotplug_support. If @hotplug_support is set, the kernel can safely
update all the required kexec segments of the kdump image during
CPU/Memory hotplug events.
Introduce an architecture-specific function to process kexec flags for
determining hotplug support. Set the @hotplug_support member of struct
kimage for both kexec_load and kexec_file_load system calls. This
simplifies kernel checks to identify hotplug support for the currently
loaded kdump image by just examining the value of @hotplug_support.
Couple of minor nits. See comments below.
Otherwise, looks good to me.
Acked-by: Hari Bathini
Signed-off-by: Sourabh Jain
Cc: Akhil Raj
Cc: Andrew Morton
Cc: Aneesh Kumar K.V
Cc: Baoquan He
Cc: Borislav Petkov (AMD)
Cc: Boris Ostrovsky
Cc: Christophe Leroy
Cc: Dave Hansen
Cc: Dave Young
Cc: David Hildenbrand
Cc: Eric DeVolder
Cc: Greg Kroah-Hartman
Cc: Hari Bathini
Cc: Laurent Dufour
Cc: Mahesh Salgaonkar
Cc: Michael Ellerman
Cc: Mimi Zohar
Cc: Naveen N Rao
Cc: Oscar Salvador
Cc: Thomas Gleixner
Cc: Valentin Schneider
Cc: Vivek Goyal
Cc: ke...@lists.infradead.org
Cc: x...@kernel.org
---
arch/x86/include/asm/kexec.h | 11 ++-
arch/x86/kernel/crash.c | 28 +---
drivers/base/cpu.c | 2 +-
drivers/base/memory.c| 2 +-
include/linux/crash_core.h | 13 ++---
include/linux/kexec.h| 11 +++
include/uapi/linux/kexec.h | 1 +
kernel/crash_core.c | 11 ---
kernel/kexec.c | 4 ++--
kernel/kexec_file.c | 5 +
10 files changed, 46 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index cb1320ebbc23..ae5482a2f0ca 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void);
-#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void);
-#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
-#endif
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags);
+#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2a682fe86352..f06501445cd9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
-/* These functions provide the value for the sysfs crash_hotplug nodes */
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void)
+int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{
- return crash_check_update_elfcorehdr();
-}
-#endif
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void)
-{
- return crash_check_update_elfcorehdr();
-}
+#ifdef CONFIG_KEXEC_FILE
+ if (image->file_mode)
+ return 1;
#endif
+ /*
+* Initially, crash hotplug support for kexec_load was added
+
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
Hello
On 29/02/24 12:58, Baoquan He wrote:
On 02/26/24 at 02:11pm, Sourabh Jain wrote:
..snip...
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 70fa8111a9d6..630c4fd7ea39 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -496,7 +496,7 @@ static DEFINE_MUTEX(__crash_hotplug_lock);
* It reflects the kernel's ability/permission to update the crash
* elfcorehdr directly.
~ this should be updated too.
*/
-int crash_check_update_elfcorehdr(void)
+int crash_check_hotplug_support(void)
{
int rc = 0;
@@ -508,10 +508,7 @@ int crash_check_update_elfcorehdr(void)
return 0;
}
if (kexec_crash_image) {
- if (kexec_crash_image->file_mode)
- rc = 1;
- else
- rc = kexec_crash_image->update_elfcorehdr;
+ rc = kexec_crash_image->hotplug_support;
}
/* Release lock now that update complete */
kexec_unlock();
@@ -552,8 +549,8 @@ static void crash_handle_hotplug_event(unsigned int
hp_action, unsigned int cpu,
image = kexec_crash_image;
- /* Check that updating elfcorehdr is permitted */
- if (!(image->file_mode || image->update_elfcorehdr))
+ /* Check that kexec segments update is permitted */
+ if (!image->hotplug_support)
goto out;
if (hp_action == KEXEC_CRASH_HP_ADD_CPU ||
diff --git a/kernel/kexec.c b/kernel/kexec.c
index bab542fc1463..a6b3f96bb50c 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -135,8 +135,8 @@ static int do_kexec_load(unsigned long entry, unsigned long
nr_segments,
image->preserve_context = 1;
#ifdef CONFIG_CRASH_HOTPLUG
- if (flags & KEXEC_UPDATE_ELFCOREHDR)
- image->update_elfcorehdr = 1;
+ if ((flags & KEXEC_ON_CRASH) && arch_crash_hotplug_support(image,
flags))
+ image->hotplug_support = 1;
#endif
ret = machine_kexec_prepare(image);
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 2d1db05fbf04..3d64290d24c9 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -376,6 +376,11 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int,
initrd_fd,
if (ret)
goto out;
+#ifdef CONFIG_CRASH_HOTPLUG
+ if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image,
flags))
+ image->hotplug_support = 1;
+#endif
+
ret = machine_kexec_prepare(image);
if (ret)
goto out;
Other than the tiny part, the overall looks good to me.
Acked-by: Baoquan He
Thank you for the review and feedback.
- Sourabh
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
Hello Baoquan,
On 29/02/24 12:58, Baoquan He wrote:
On 02/26/24 at 02:11pm, Sourabh Jain wrote:
..snip...
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 70fa8111a9d6..630c4fd7ea39 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -496,7 +496,7 @@ static DEFINE_MUTEX(__crash_hotplug_lock);
* It reflects the kernel's ability/permission to update the crash
* elfcorehdr directly.
~ this should be updated too.
Yes, it should.
Thanks,
Sourabh
*/
-int crash_check_update_elfcorehdr(void)
+int crash_check_hotplug_support(void)
{
int rc = 0;
@@ -508,10 +508,7 @@ int crash_check_update_elfcorehdr(void)
return 0;
}
if (kexec_crash_image) {
- if (kexec_crash_image->file_mode)
- rc = 1;
- else
- rc = kexec_crash_image->update_elfcorehdr;
+ rc = kexec_crash_image->hotplug_support;
}
/* Release lock now that update complete */
kexec_unlock();
@@ -552,8 +549,8 @@ static void crash_handle_hotplug_event(unsigned int
hp_action, unsigned int cpu,
image = kexec_crash_image;
- /* Check that updating elfcorehdr is permitted */
- if (!(image->file_mode || image->update_elfcorehdr))
+ /* Check that kexec segments update is permitted */
+ if (!image->hotplug_support)
goto out;
if (hp_action == KEXEC_CRASH_HP_ADD_CPU ||
diff --git a/kernel/kexec.c b/kernel/kexec.c
index bab542fc1463..a6b3f96bb50c 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -135,8 +135,8 @@ static int do_kexec_load(unsigned long entry, unsigned long
nr_segments,
image->preserve_context = 1;
#ifdef CONFIG_CRASH_HOTPLUG
- if (flags & KEXEC_UPDATE_ELFCOREHDR)
- image->update_elfcorehdr = 1;
+ if ((flags & KEXEC_ON_CRASH) && arch_crash_hotplug_support(image,
flags))
+ image->hotplug_support = 1;
#endif
ret = machine_kexec_prepare(image);
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 2d1db05fbf04..3d64290d24c9 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -376,6 +376,11 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int,
initrd_fd,
if (ret)
goto out;
+#ifdef CONFIG_CRASH_HOTPLUG
+ if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image,
flags))
+ image->hotplug_support = 1;
+#endif
+
ret = machine_kexec_prepare(image);
if (ret)
goto out;
Other than the tiny part, the overall looks good to me.
Acked-by: Baoquan He
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
On 29/02/24 11:26, Baoquan He wrote:
On 02/29/24 at 10:35am, Sourabh Jain wrote:
Hello Baoquan,
Do you have any comments or suggestions for this patch series, especially
for this patch?
Have applied this series and reviewing, will ack or add comment if any
concern. Thanks.
Thanks, looking forward to your feedback!
- Sourabh
On 26/02/24 14:11, Sourabh Jain wrote:
Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.
However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.
Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
the kernel, it indicates to the kernel that all the required kexec
segment is skipped from SHA calculation and it is safe to update kdump
image loaded using the kexec_load syscall.
While loading the kdump image using the kexec_load syscall, the
@update_elfcorehdr member of struct kimage is set if the kexec tool
sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
to determine whether it is safe to update elfcorehdr on hotplug events.
However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
flag, the kexec tool could mark all the required kexec segments on an
architecture as safe to update. So rename the @update_elfcorehdr to
@hotplug_support. If @hotplug_support is set, the kernel can safely
update all the required kexec segments of the kdump image during
CPU/Memory hotplug events.
Introduce an architecture-specific function to process kexec flags for
determining hotplug support. Set the @hotplug_support member of struct
kimage for both kexec_load and kexec_file_load system calls. This
simplifies kernel checks to identify hotplug support for the currently
loaded kdump image by just examining the value of @hotplug_support.
Signed-off-by: Sourabh Jain
Cc: Akhil Raj
Cc: Andrew Morton
Cc: Aneesh Kumar K.V
Cc: Baoquan He
Cc: Borislav Petkov (AMD)
Cc: Boris Ostrovsky
Cc: Christophe Leroy
Cc: Dave Hansen
Cc: Dave Young
Cc: David Hildenbrand
Cc: Eric DeVolder
Cc: Greg Kroah-Hartman
Cc: Hari Bathini
Cc: Laurent Dufour
Cc: Mahesh Salgaonkar
Cc: Michael Ellerman
Cc: Mimi Zohar
Cc: Naveen N Rao
Cc: Oscar Salvador
Cc: Thomas Gleixner
Cc: Valentin Schneider
Cc: Vivek Goyal
Cc: ke...@lists.infradead.org
Cc: x...@kernel.org
---
arch/x86/include/asm/kexec.h | 11 ++-
arch/x86/kernel/crash.c | 28 +---
drivers/base/cpu.c | 2 +-
drivers/base/memory.c| 2 +-
include/linux/crash_core.h | 13 ++---
include/linux/kexec.h| 11 +++
include/uapi/linux/kexec.h | 1 +
kernel/crash_core.c | 11 ---
kernel/kexec.c | 4 ++--
kernel/kexec_file.c | 5 +
10 files changed, 46 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index cb1320ebbc23..ae5482a2f0ca 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void);
-#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void);
-#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
-#endif
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags);
+#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2a682fe86352..f06501445cd9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
-/* These functions provide the value for the sysfs crash_hotplug nodes */
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void)
+int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{
- return crash_check_update_elfcorehdr();
-}
-#endif
-#ifdef CONFIG_MEMORY_HOTPLUG
-int
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
On 02/26/24 at 02:11pm, Sourabh Jain wrote:
..snip...
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 70fa8111a9d6..630c4fd7ea39 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -496,7 +496,7 @@ static DEFINE_MUTEX(__crash_hotplug_lock);
> * It reflects the kernel's ability/permission to update the crash
> * elfcorehdr directly.
~ this should be updated too.
> */
> -int crash_check_update_elfcorehdr(void)
> +int crash_check_hotplug_support(void)
> {
> int rc = 0;
>
> @@ -508,10 +508,7 @@ int crash_check_update_elfcorehdr(void)
> return 0;
> }
> if (kexec_crash_image) {
> - if (kexec_crash_image->file_mode)
> - rc = 1;
> - else
> - rc = kexec_crash_image->update_elfcorehdr;
> + rc = kexec_crash_image->hotplug_support;
> }
> /* Release lock now that update complete */
> kexec_unlock();
> @@ -552,8 +549,8 @@ static void crash_handle_hotplug_event(unsigned int
> hp_action, unsigned int cpu,
>
> image = kexec_crash_image;
>
> - /* Check that updating elfcorehdr is permitted */
> - if (!(image->file_mode || image->update_elfcorehdr))
> + /* Check that kexec segments update is permitted */
> + if (!image->hotplug_support)
> goto out;
>
> if (hp_action == KEXEC_CRASH_HP_ADD_CPU ||
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index bab542fc1463..a6b3f96bb50c 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -135,8 +135,8 @@ static int do_kexec_load(unsigned long entry, unsigned
> long nr_segments,
> image->preserve_context = 1;
>
> #ifdef CONFIG_CRASH_HOTPLUG
> - if (flags & KEXEC_UPDATE_ELFCOREHDR)
> - image->update_elfcorehdr = 1;
> + if ((flags & KEXEC_ON_CRASH) && arch_crash_hotplug_support(image,
> flags))
> + image->hotplug_support = 1;
> #endif
>
> ret = machine_kexec_prepare(image);
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 2d1db05fbf04..3d64290d24c9 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -376,6 +376,11 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int,
> initrd_fd,
> if (ret)
> goto out;
>
> +#ifdef CONFIG_CRASH_HOTPLUG
> + if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image,
> flags))
> + image->hotplug_support = 1;
> +#endif
> +
> ret = machine_kexec_prepare(image);
> if (ret)
> goto out;
Other than the tiny part, the overall looks good to me.
Acked-by: Baoquan He
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
On 02/29/24 at 10:35am, Sourabh Jain wrote:
> Hello Baoquan,
>
> Do you have any comments or suggestions for this patch series, especially
> for this patch?
Have applied this series and reviewing, will ack or add comment if any
concern. Thanks.
> On 26/02/24 14:11, Sourabh Jain wrote:
> > Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
> > introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
> > this flag to indicate to the kernel that it is safe to modify the
> > elfcorehdr of the kdump image loaded using the kexec_load system call.
> >
> > However, it is possible that architectures may need to update kexec
> > segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
> > on PowerPC. Introducing a new kexec flag for every new kexec segment
> > may not be a good solution. Hence, a generic kexec flag bit,
> > `KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
> > hotplug support intent between the kexec tool and the kernel for the
> > kexec_load system call.
> >
> > Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
> > the kernel, it indicates to the kernel that all the required kexec
> > segment is skipped from SHA calculation and it is safe to update kdump
> > image loaded using the kexec_load syscall.
> >
> > While loading the kdump image using the kexec_load syscall, the
> > @update_elfcorehdr member of struct kimage is set if the kexec tool
> > sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
> > to determine whether it is safe to update elfcorehdr on hotplug events.
> > However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
> > flag, the kexec tool could mark all the required kexec segments on an
> > architecture as safe to update. So rename the @update_elfcorehdr to
> > @hotplug_support. If @hotplug_support is set, the kernel can safely
> > update all the required kexec segments of the kdump image during
> > CPU/Memory hotplug events.
> >
> > Introduce an architecture-specific function to process kexec flags for
> > determining hotplug support. Set the @hotplug_support member of struct
> > kimage for both kexec_load and kexec_file_load system calls. This
> > simplifies kernel checks to identify hotplug support for the currently
> > loaded kdump image by just examining the value of @hotplug_support.
> >
> > Signed-off-by: Sourabh Jain
> > Cc: Akhil Raj
> > Cc: Andrew Morton
> > Cc: Aneesh Kumar K.V
> > Cc: Baoquan He
> > Cc: Borislav Petkov (AMD)
> > Cc: Boris Ostrovsky
> > Cc: Christophe Leroy
> > Cc: Dave Hansen
> > Cc: Dave Young
> > Cc: David Hildenbrand
> > Cc: Eric DeVolder
> > Cc: Greg Kroah-Hartman
> > Cc: Hari Bathini
> > Cc: Laurent Dufour
> > Cc: Mahesh Salgaonkar
> > Cc: Michael Ellerman
> > Cc: Mimi Zohar
> > Cc: Naveen N Rao
> > Cc: Oscar Salvador
> > Cc: Thomas Gleixner
> > Cc: Valentin Schneider
> > Cc: Vivek Goyal
> > Cc: ke...@lists.infradead.org
> > Cc: x...@kernel.org
> > ---
> > arch/x86/include/asm/kexec.h | 11 ++-
> > arch/x86/kernel/crash.c | 28 +---
> > drivers/base/cpu.c | 2 +-
> > drivers/base/memory.c| 2 +-
> > include/linux/crash_core.h | 13 ++---
> > include/linux/kexec.h| 11 +++
> > include/uapi/linux/kexec.h | 1 +
> > kernel/crash_core.c | 11 ---
> > kernel/kexec.c | 4 ++--
> > kernel/kexec_file.c | 5 +
> > 10 files changed, 46 insertions(+), 42 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
> > index cb1320ebbc23..ae5482a2f0ca 100644
> > --- a/arch/x86/include/asm/kexec.h
> > +++ b/arch/x86/include/asm/kexec.h
> > @@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
> > void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
> > #define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
> > -#ifdef CONFIG_HOTPLUG_CPU
> > -int arch_crash_hotplug_cpu_support(void);
> > -#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
> > -#endif
> > -
> > -#ifdef CONFIG_MEMORY_HOTPLUG
> > -int arch_crash_hotplug_memory_support(void);
> > -#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
> > -#endif
> > +int arch_crash_hotplug_support(struct kimage *image, unsigned long
> > kexec_flags);
> > +#define arch_crash_hotplug_support arch_crash_hotplug_support
> > unsigned int arch_crash_get_elfcorehdr_size(void);
> > #define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
> > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> > index 2a682fe86352..f06501445cd9 100644
> > --- a/arch/x86/kernel/crash.c
> > +++ b/arch/x86/kernel/crash.c
> > @@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
> > #undef pr_fmt
> > #define pr_fmt(fmt) "crash hp: " fmt
> > -/* These functions provide the value for the sysfs
Re: [PATCH v17 2/6] crash: add a new kexec flag for hotplug support
Hello Baoquan,
Do you have any comments or suggestions for this patch series,
especially for this patch?
Thanks,
Sourabh
On 26/02/24 14:11, Sourabh Jain wrote:
Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.
However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.
Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
the kernel, it indicates to the kernel that all the required kexec
segment is skipped from SHA calculation and it is safe to update kdump
image loaded using the kexec_load syscall.
While loading the kdump image using the kexec_load syscall, the
@update_elfcorehdr member of struct kimage is set if the kexec tool
sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
to determine whether it is safe to update elfcorehdr on hotplug events.
However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
flag, the kexec tool could mark all the required kexec segments on an
architecture as safe to update. So rename the @update_elfcorehdr to
@hotplug_support. If @hotplug_support is set, the kernel can safely
update all the required kexec segments of the kdump image during
CPU/Memory hotplug events.
Introduce an architecture-specific function to process kexec flags for
determining hotplug support. Set the @hotplug_support member of struct
kimage for both kexec_load and kexec_file_load system calls. This
simplifies kernel checks to identify hotplug support for the currently
loaded kdump image by just examining the value of @hotplug_support.
Signed-off-by: Sourabh Jain
Cc: Akhil Raj
Cc: Andrew Morton
Cc: Aneesh Kumar K.V
Cc: Baoquan He
Cc: Borislav Petkov (AMD)
Cc: Boris Ostrovsky
Cc: Christophe Leroy
Cc: Dave Hansen
Cc: Dave Young
Cc: David Hildenbrand
Cc: Eric DeVolder
Cc: Greg Kroah-Hartman
Cc: Hari Bathini
Cc: Laurent Dufour
Cc: Mahesh Salgaonkar
Cc: Michael Ellerman
Cc: Mimi Zohar
Cc: Naveen N Rao
Cc: Oscar Salvador
Cc: Thomas Gleixner
Cc: Valentin Schneider
Cc: Vivek Goyal
Cc: ke...@lists.infradead.org
Cc: x...@kernel.org
---
arch/x86/include/asm/kexec.h | 11 ++-
arch/x86/kernel/crash.c | 28 +---
drivers/base/cpu.c | 2 +-
drivers/base/memory.c| 2 +-
include/linux/crash_core.h | 13 ++---
include/linux/kexec.h| 11 +++
include/uapi/linux/kexec.h | 1 +
kernel/crash_core.c | 11 ---
kernel/kexec.c | 4 ++--
kernel/kexec_file.c | 5 +
10 files changed, 46 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index cb1320ebbc23..ae5482a2f0ca 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void);
-#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void);
-#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
-#endif
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags);
+#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2a682fe86352..f06501445cd9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
-/* These functions provide the value for the sysfs crash_hotplug nodes */
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void)
+int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{
- return crash_check_update_elfcorehdr();
-}
-#endif
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void)
-{
- return crash_check_update_elfcorehdr();
-}
+#ifdef CONFIG_KEXEC_FILE
+ if (image->file_mode)
+ return 1;
#endif
+ /*
+* Initially, crash hotplug support for
[PATCH v17 2/6] crash: add a new kexec flag for hotplug support
Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.
However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.
Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to
the kernel, it indicates to the kernel that all the required kexec
segment is skipped from SHA calculation and it is safe to update kdump
image loaded using the kexec_load syscall.
While loading the kdump image using the kexec_load syscall, the
@update_elfcorehdr member of struct kimage is set if the kexec tool
sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used
to determine whether it is safe to update elfcorehdr on hotplug events.
However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec
flag, the kexec tool could mark all the required kexec segments on an
architecture as safe to update. So rename the @update_elfcorehdr to
@hotplug_support. If @hotplug_support is set, the kernel can safely
update all the required kexec segments of the kdump image during
CPU/Memory hotplug events.
Introduce an architecture-specific function to process kexec flags for
determining hotplug support. Set the @hotplug_support member of struct
kimage for both kexec_load and kexec_file_load system calls. This
simplifies kernel checks to identify hotplug support for the currently
loaded kdump image by just examining the value of @hotplug_support.
Signed-off-by: Sourabh Jain
Cc: Akhil Raj
Cc: Andrew Morton
Cc: Aneesh Kumar K.V
Cc: Baoquan He
Cc: Borislav Petkov (AMD)
Cc: Boris Ostrovsky
Cc: Christophe Leroy
Cc: Dave Hansen
Cc: Dave Young
Cc: David Hildenbrand
Cc: Eric DeVolder
Cc: Greg Kroah-Hartman
Cc: Hari Bathini
Cc: Laurent Dufour
Cc: Mahesh Salgaonkar
Cc: Michael Ellerman
Cc: Mimi Zohar
Cc: Naveen N Rao
Cc: Oscar Salvador
Cc: Thomas Gleixner
Cc: Valentin Schneider
Cc: Vivek Goyal
Cc: ke...@lists.infradead.org
Cc: x...@kernel.org
---
arch/x86/include/asm/kexec.h | 11 ++-
arch/x86/kernel/crash.c | 28 +---
drivers/base/cpu.c | 2 +-
drivers/base/memory.c| 2 +-
include/linux/crash_core.h | 13 ++---
include/linux/kexec.h| 11 +++
include/uapi/linux/kexec.h | 1 +
kernel/crash_core.c | 11 ---
kernel/kexec.c | 4 ++--
kernel/kexec_file.c | 5 +
10 files changed, 46 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index cb1320ebbc23..ae5482a2f0ca 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -210,15 +210,8 @@ extern void kdump_nmi_shootdown_cpus(void);
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void);
-#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void);
-#define crash_hotplug_memory_support arch_crash_hotplug_memory_support
-#endif
+int arch_crash_hotplug_support(struct kimage *image, unsigned long
kexec_flags);
+#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2a682fe86352..f06501445cd9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -402,20 +402,26 @@ int crash_load_segments(struct kimage *image)
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
-/* These functions provide the value for the sysfs crash_hotplug nodes */
-#ifdef CONFIG_HOTPLUG_CPU
-int arch_crash_hotplug_cpu_support(void)
+int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{
- return crash_check_update_elfcorehdr();
-}
-#endif
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_crash_hotplug_memory_support(void)
-{
- return crash_check_update_elfcorehdr();
-}
+#ifdef CONFIG_KEXEC_FILE
+ if (image->file_mode)
+ return 1;
#endif
+ /*
+* Initially, crash hotplug support for kexec_load was added
+* with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this
+* functionality was expanded to accommodate multiple kexec
+* segment updates, leading to the
