* [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
@ 2023-09-01 19:04 Hari Bathini
2023-09-01 19:04 ` [PATCH 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active Hari Bathini
2023-09-03 3:36 ` [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Baoquan He
0 siblings, 2 replies; 6+ messages in thread
From: Hari Bathini @ 2023-09-01 19:04 UTC (permalink / raw)
To: lkml, linuxppc-dev, Kexec-ml
Cc: Sourabh Jain, Dave Young, Mahesh J Salgaonkar, Baoquan He
Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
While elfcorehdr_addr is set for kexec based kernel dump mechanism,
alternate dump capturing methods like fadump [1] also set it to export
the vmcore. is_kdump_kernel() is used to restrict resources in crash
dump capture kernel but such restrictions may not be desirable for
fadump. Allow is_kdump_kernel() to be defined differently for such
scenarios. With this, is_kdump_kernel() could be false while vmcore
is usable. So, introduce is_crashdump_kernel() to return true when
elfcorehdr_addr is set and use it for vmcore related checks.
[1] https://docs.kernel.org/powerpc/firmware-assisted-dump.html
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
include/linux/crash_dump.h | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0f3a656293b0..1052a0faf0dd 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -50,6 +50,7 @@ void vmcore_cleanup(void);
#define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
#endif
+#ifndef is_kdump_kernel
/*
* is_kdump_kernel() checks whether this kernel is booting after a panic of
* previous kernel or not. This is determined by checking if previous kernel
@@ -64,6 +65,19 @@ static inline bool is_kdump_kernel(void)
{
return elfcorehdr_addr != ELFCORE_ADDR_MAX;
}
+#endif
+
+/*
+ * Return true if this is a dump capture kernel, where vmcore needs to be
+ * exported, irrespective of the dump capture mechanism in use.
+ *
+ * Same as is_kdump_kernel() unless arch specific code defines is_kdump_kernel()
+ * differently while supporting other dump capturing mechanisms.
+ */
+static inline bool is_crashdump_kernel(void)
+{
+ return elfcorehdr_addr != ELFCORE_ADDR_MAX;
+}
/* is_vmcore_usable() checks if the kernel is booting after a panic and
* the vmcore region is usable.
@@ -75,7 +89,7 @@ static inline bool is_kdump_kernel(void)
static inline int is_vmcore_usable(void)
{
- return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
+ return is_crashdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
}
/* vmcore_unusable() marks the vmcore as unusable,
@@ -84,7 +98,7 @@ static inline int is_vmcore_usable(void)
static inline void vmcore_unusable(void)
{
- if (is_kdump_kernel())
+ if (is_crashdump_kernel())
elfcorehdr_addr = ELFCORE_ADDR_ERR;
}
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active
2023-09-01 19:04 [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Hari Bathini
@ 2023-09-01 19:04 ` Hari Bathini
2023-09-03 3:36 ` [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Baoquan He
1 sibling, 0 replies; 6+ messages in thread
From: Hari Bathini @ 2023-09-01 19:04 UTC (permalink / raw)
To: lkml, linuxppc-dev, Kexec-ml
Cc: Sourabh Jain, Dave Young, Mahesh J Salgaonkar, Baoquan He
Currently, is_kdump_kernel() returns true in crash dump capture kernel
for both kdump and fadump crash dump capturing methods, as both these
methods set elfcorehdr_addr. Some restrictions enforced for crash dump
capture kernel, based on is_kdump_kernel(), are specifically meant for
kdump case and not desirable for fadump - eg. IO queues restriction in
device drivers. So, define is_kdump_kernel() to return false when f/w
assisted adump is active. For fadump case, is_fadump_active() can be
used for capture kernel specific checks.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
arch/powerpc/include/asm/kexec.h | 8 ++++++--
arch/powerpc/kernel/crash_dump.c | 12 ++++++++++++
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index a1ddba01e7d1..e1b43aa12175 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -99,10 +99,14 @@ void relocate_new_kernel(unsigned long indirection_page, unsigned long reboot_co
void kexec_copy_flush(struct kimage *image);
-#if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
+#if defined(CONFIG_CRASH_DUMP)
+bool is_kdump_kernel(void);
+#define is_kdump_kernel is_kdump_kernel
+#if defined(CONFIG_PPC_RTAS)
void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
#define crash_free_reserved_phys_range crash_free_reserved_phys_range
-#endif
+#endif /* CONFIG_PPC_RTAS */
+#endif /* CONFIG_CRASH_DUMP */
#ifdef CONFIG_KEXEC_FILE
extern const struct kexec_file_ops kexec_elf64_ops;
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 9a3b85bfc83f..2086fa6cdc25 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -19,6 +19,7 @@
#include <linux/uio.h>
#include <asm/rtas.h>
#include <asm/inst.h>
+#include <asm/fadump.h>
#ifdef DEBUG
#include <asm/udbg.h>
@@ -92,6 +93,17 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
return csize;
}
+/*
+ * Return true only when kexec based kernel dump capturing method is used.
+ * This ensures all restritions applied for kdump case are not automatically
+ * applied for fadump case.
+ */
+bool is_kdump_kernel(void)
+{
+ return !is_fadump_active() && elfcorehdr_addr != ELFCORE_ADDR_MAX;
+}
+EXPORT_SYMBOL_GPL(is_kdump_kernel);
+
#ifdef CONFIG_PPC_RTAS
/*
* The crashkernel region will almost always overlap the RTAS region, so
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
2023-09-01 19:04 [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Hari Bathini
2023-09-01 19:04 ` [PATCH 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active Hari Bathini
@ 2023-09-03 3:36 ` Baoquan He
2023-09-04 14:34 ` Hari Bathini
1 sibling, 1 reply; 6+ messages in thread
From: Baoquan He @ 2023-09-03 3:36 UTC (permalink / raw)
To: Hari Bathini
Cc: linuxppc-dev, Kexec-ml, lkml, Sourabh Jain, Mahesh J Salgaonkar,
Dave Young
Hi Hari,
On 09/02/23 at 12:34am, Hari Bathini wrote:
> Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
> While elfcorehdr_addr is set for kexec based kernel dump mechanism,
> alternate dump capturing methods like fadump [1] also set it to export
> the vmcore. is_kdump_kernel() is used to restrict resources in crash
> dump capture kernel but such restrictions may not be desirable for
> fadump. Allow is_kdump_kernel() to be defined differently for such
> scenarios. With this, is_kdump_kernel() could be false while vmcore
> is usable. So, introduce is_crashdump_kernel() to return true when
> elfcorehdr_addr is set and use it for vmcore related checks.
I got what is done in these two patches, but didn't get why they need be
done. vmcore_unusable()/is_vmcore_usable() are only unitilized in ia64.
Why do you care if it's is_crashdump_kernel() or is_kdump_kernel()?
If you want to override the generic is_kdump_kernel() with powerpc's own
is_kdump_kernel(), your below change is enough to allow you to do that.
I can't see why is_crashdump_kernel() is needed. Could you explain that
specifically?
#ifndef is_kdump_kernel
static inline bool is_kdump_kernel(void)
{
return elfcorehdr_addr != ELFCORE_ADDR_MAX;
}
#endif
Thanks
Baoquan
> [1] https://docs.kernel.org/powerpc/firmware-assisted-dump.html
>
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> ---
> include/linux/crash_dump.h | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> index 0f3a656293b0..1052a0faf0dd 100644
> --- a/include/linux/crash_dump.h
> +++ b/include/linux/crash_dump.h
> @@ -50,6 +50,7 @@ void vmcore_cleanup(void);
> #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
> #endif
>
> +#ifndef is_kdump_kernel
> /*
> * is_kdump_kernel() checks whether this kernel is booting after a panic of
> * previous kernel or not. This is determined by checking if previous kernel
> @@ -64,6 +65,19 @@ static inline bool is_kdump_kernel(void)
> {
> return elfcorehdr_addr != ELFCORE_ADDR_MAX;
> }
> +#endif
> +
> +/*
> + * Return true if this is a dump capture kernel, where vmcore needs to be
> + * exported, irrespective of the dump capture mechanism in use.
> + *
> + * Same as is_kdump_kernel() unless arch specific code defines is_kdump_kernel()
> + * differently while supporting other dump capturing mechanisms.
> + */
> +static inline bool is_crashdump_kernel(void)
> +{
> + return elfcorehdr_addr != ELFCORE_ADDR_MAX;
> +}
>
> /* is_vmcore_usable() checks if the kernel is booting after a panic and
> * the vmcore region is usable.
> @@ -75,7 +89,7 @@ static inline bool is_kdump_kernel(void)
>
> static inline int is_vmcore_usable(void)
> {
> - return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
> + return is_crashdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
> }
>
> /* vmcore_unusable() marks the vmcore as unusable,
> @@ -84,7 +98,7 @@ static inline int is_vmcore_usable(void)
>
> static inline void vmcore_unusable(void)
> {
> - if (is_kdump_kernel())
> + if (is_crashdump_kernel())
> elfcorehdr_addr = ELFCORE_ADDR_ERR;
> }
>
> --
> 2.41.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
2023-09-03 3:36 ` [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Baoquan He
@ 2023-09-04 14:34 ` Hari Bathini
2023-09-05 2:30 ` Baoquan He
0 siblings, 1 reply; 6+ messages in thread
From: Hari Bathini @ 2023-09-04 14:34 UTC (permalink / raw)
To: Baoquan He
Cc: linuxppc-dev, Kexec-ml, lkml, Sourabh Jain, Mahesh J Salgaonkar,
Dave Young
Hi Baoquan,
Thanks for the review...
On 03/09/23 9:06 am, Baoquan He wrote:
> Hi Hari,
>
> On 09/02/23 at 12:34am, Hari Bathini wrote:
>> Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
>> While elfcorehdr_addr is set for kexec based kernel dump mechanism,
>> alternate dump capturing methods like fadump [1] also set it to export
>> the vmcore. is_kdump_kernel() is used to restrict resources in crash
>> dump capture kernel but such restrictions may not be desirable for
>> fadump. Allow is_kdump_kernel() to be defined differently for such
>> scenarios. With this, is_kdump_kernel() could be false while vmcore
>> is usable. So, introduce is_crashdump_kernel() to return true when
>> elfcorehdr_addr is set and use it for vmcore related checks.
>
> I got what is done in these two patches, but didn't get why they need be
> done. vmcore_unusable()/is_vmcore_usable() are only unitilized in ia64.
> Why do you care if it's is_crashdump_kernel() or is_kdump_kernel()?
> If you want to override the generic is_kdump_kernel() with powerpc's own
> is_kdump_kernel(), your below change is enough to allow you to do that.
> I can't see why is_crashdump_kernel() is needed. Could you explain that
> specifically?
You mean to just remove is_kdump_kernel() check in is_vmcore_usable() &
vmcore_unusable() functions? Replaced generic is_crashdump_kernel()
function instead, that returns true for any dump capturing method,
irrespective of whether is_kdump_kernel() returns true or false.
For fadump case, is_kdump_kernel() will return false after patch 2/2.
Thanks
Hari
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
2023-09-04 14:34 ` Hari Bathini
@ 2023-09-05 2:30 ` Baoquan He
2023-09-05 19:25 ` Hari Bathini
0 siblings, 1 reply; 6+ messages in thread
From: Baoquan He @ 2023-09-05 2:30 UTC (permalink / raw)
To: Hari Bathini
Cc: linuxppc-dev, Kexec-ml, lkml, Sourabh Jain, Mahesh J Salgaonkar,
Dave Young
On 09/04/23 at 08:04pm, Hari Bathini wrote:
> Hi Baoquan,
>
> Thanks for the review...
>
> On 03/09/23 9:06 am, Baoquan He wrote:
> > Hi Hari,
> >
> > On 09/02/23 at 12:34am, Hari Bathini wrote:
> > > Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
> > > While elfcorehdr_addr is set for kexec based kernel dump mechanism,
> > > alternate dump capturing methods like fadump [1] also set it to export
> > > the vmcore. is_kdump_kernel() is used to restrict resources in crash
> > > dump capture kernel but such restrictions may not be desirable for
> > > fadump. Allow is_kdump_kernel() to be defined differently for such
> > > scenarios. With this, is_kdump_kernel() could be false while vmcore
> > > is usable. So, introduce is_crashdump_kernel() to return true when
> > > elfcorehdr_addr is set and use it for vmcore related checks.
> >
> > I got what is done in these two patches, but didn't get why they need be
> > done. vmcore_unusable()/is_vmcore_usable() are only unitilized in ia64.
> > Why do you care if it's is_crashdump_kernel() or is_kdump_kernel()?
> > If you want to override the generic is_kdump_kernel() with powerpc's own
> > is_kdump_kernel(), your below change is enough to allow you to do that.
> > I can't see why is_crashdump_kernel() is needed. Could you explain that
> > specifically?
>
> You mean to just remove is_kdump_kernel() check in is_vmcore_usable() &
> vmcore_unusable() functions? Replaced generic is_crashdump_kernel()
> function instead, that returns true for any dump capturing method,
> irrespective of whether is_kdump_kernel() returns true or false.
> For fadump case, is_kdump_kernel() will return false after patch 2/2.
OK, I could understand what you want to achieve. You want to make
is_kdump_kernel() only return true for kdump, while is_vmcore_usable()
returns true for both kdump and fadump.
IIUC, can we change as below? It could make code clearer and more
straightforward. I don't think adding another is_crashdump_kernel()
is a good idea, that would be a torture for non-powerpc people reading
code when they need differentiate between kdump and crashdump.
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0f3a656293b0..102a8b710b38 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -50,6 +50,7 @@ void vmcore_cleanup(void);
#define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
#endif
+#ifndef is_kdump_active
/*
* is_kdump_kernel() checks whether this kernel is booting after a panic of
* previous kernel or not. This is determined by checking if previous kernel
@@ -64,6 +65,14 @@ static inline bool is_kdump_kernel(void)
{
return elfcorehdr_addr != ELFCORE_ADDR_MAX;
}
+#endif
+
+#ifndef is_fadump_active
+static inline bool is_fadump_active(void)
+{
+ return false;
+}
+#endif
/* is_vmcore_usable() checks if the kernel is booting after a panic and
* the vmcore region is usable.
@@ -75,7 +84,8 @@ static inline bool is_kdump_kernel(void)
static inline int is_vmcore_usable(void)
{
- return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
+ return (is_kdump_kernel() || is_fadump_active())
+ && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
}
/* vmcore_unusable() marks the vmcore as unusable,
@@ -84,7 +94,7 @@ static inline int is_vmcore_usable(void)
static inline void vmcore_unusable(void)
{
- if (is_kdump_kernel())
+ if (is_kdump_kernel() || is_fadump_active())
elfcorehdr_addr = ELFCORE_ADDR_ERR;
}
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel()
2023-09-05 2:30 ` Baoquan He
@ 2023-09-05 19:25 ` Hari Bathini
0 siblings, 0 replies; 6+ messages in thread
From: Hari Bathini @ 2023-09-05 19:25 UTC (permalink / raw)
To: Baoquan He
Cc: linuxppc-dev, Kexec-ml, lkml, Sourabh Jain, Mahesh J Salgaonkar,
Dave Young
On 05/09/23 8:00 am, Baoquan He wrote:
> On 09/04/23 at 08:04pm, Hari Bathini wrote:
>> Hi Baoquan,
>>
>> Thanks for the review...
>>
>> On 03/09/23 9:06 am, Baoquan He wrote:
>>> Hi Hari,
>>>
>>> On 09/02/23 at 12:34am, Hari Bathini wrote:
>>>> Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set.
>>>> While elfcorehdr_addr is set for kexec based kernel dump mechanism,
>>>> alternate dump capturing methods like fadump [1] also set it to export
>>>> the vmcore. is_kdump_kernel() is used to restrict resources in crash
>>>> dump capture kernel but such restrictions may not be desirable for
>>>> fadump. Allow is_kdump_kernel() to be defined differently for such
>>>> scenarios. With this, is_kdump_kernel() could be false while vmcore
>>>> is usable. So, introduce is_crashdump_kernel() to return true when
>>>> elfcorehdr_addr is set and use it for vmcore related checks.
>>>
>>> I got what is done in these two patches, but didn't get why they need be
>>> done. vmcore_unusable()/is_vmcore_usable() are only unitilized in ia64.
>>> Why do you care if it's is_crashdump_kernel() or is_kdump_kernel()?
>>> If you want to override the generic is_kdump_kernel() with powerpc's own
>>> is_kdump_kernel(), your below change is enough to allow you to do that.
>>> I can't see why is_crashdump_kernel() is needed. Could you explain that
>>> specifically?
>>
>> You mean to just remove is_kdump_kernel() check in is_vmcore_usable() &
>> vmcore_unusable() functions? Replaced generic is_crashdump_kernel()
>> function instead, that returns true for any dump capturing method,
>> irrespective of whether is_kdump_kernel() returns true or false.
>> For fadump case, is_kdump_kernel() will return false after patch 2/2.
>
> OK, I could understand what you want to achieve. You want to make
> is_kdump_kernel() only return true for kdump, while is_vmcore_usable()
> returns true for both kdump and fadump.
>
> IIUC, can we change as below? It could make code clearer and more
> straightforward. I don't think adding another is_crashdump_kernel()
> is a good idea, that would be a torture for non-powerpc people reading
> code when they need differentiate between kdump and crashdump.
>
Sure, Baoquan.
Posted v2 based on your suggestion.
Thanks
Hari
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-09-05 19:27 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2023-09-01 19:04 [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Hari Bathini
2023-09-01 19:04 ` [PATCH 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active Hari Bathini
2023-09-03 3:36 ` [PATCH 1/2] vmcore: allow alternate dump capturing methods to export vmcore without is_kdump_kernel() Baoquan He
2023-09-04 14:34 ` Hari Bathini
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