Re: [PATCH v2 2/3] vmcore: allow fadump to export vmcore even if is_kdump_kernel() is false

2023-09-12 Thread Hari Bathini 




On 11/09/23 4:01 pm, Baoquan He wrote:

On 09/11/23 at 05:13pm, Michael Ellerman wrote:

Hari Bathini  writes:

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. Since, is_kdump_kernel() is used to restrict resources in
crash dump capture kernel and such restrictions are not desirable for
fadump, allow is_kdump_kernel() to be defined differently for fadump
case. With that change, include is_fadump_active() check in functions
is_vmcore_usable() & vmcore_unusable() to be able to export vmcore for
fadump case too.

...

diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0f3a656293b0..de8a9fabfb6f 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
+
+#ifndef is_fadump_active
+/*
+ * If f/w assisted dump capturing mechanism (fadump), instead of kexec based
+ * dump capturing mechanism (kdump) is exporting the vmcore, then this function
+ * will be defined in arch specific code to return true, when appropriate.
+ */
+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 +89,8 @@ 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 +99,7 @@ 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;
  }


I think it would be cleaner to decouple is_vmcore_usable() and
vmcore_usable() from is_kdump_kernel().

ie, make them operate solely based on the value of elforehdr_addr:

static inline int is_vmcore_usable(void)
{
elfcorehdr_addr != ELFCORE_ADDR_ERR && \
elfcorehdr_addr != ELFCORE_ADDR_MAX;


Agree. I fell into the blind corner of thinking earlier. Above change
is better.


Thanks for the reviews.
Posted v3.

- Hari

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Re: [PATCH v2 2/3] vmcore: allow fadump to export vmcore even if is_kdump_kernel() is false

2023-09-11 Thread Baoquan He 
On 09/11/23 at 05:13pm, Michael Ellerman wrote:
> Hari Bathini  writes:
> > 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. Since, is_kdump_kernel() is used to restrict resources in
> > crash dump capture kernel and such restrictions are not desirable for
> > fadump, allow is_kdump_kernel() to be defined differently for fadump
> > case. With that change, include is_fadump_active() check in functions
> > is_vmcore_usable() & vmcore_unusable() to be able to export vmcore for
> > fadump case too.
> ...
> > diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> > index 0f3a656293b0..de8a9fabfb6f 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
> > +
> > +#ifndef is_fadump_active
> > +/*
> > + * If f/w assisted dump capturing mechanism (fadump), instead of kexec 
> > based
> > + * dump capturing mechanism (kdump) is exporting the vmcore, then this 
> > function
> > + * will be defined in arch specific code to return true, when appropriate.
> > + */
> > +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 +89,8 @@ 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 +99,7 @@ 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;
> >  }
> 
> I think it would be cleaner to decouple is_vmcore_usable() and
> vmcore_usable() from is_kdump_kernel().
> 
> ie, make them operate solely based on the value of elforehdr_addr:
> 
> static inline int is_vmcore_usable(void)
> {
>   elfcorehdr_addr != ELFCORE_ADDR_ERR && \
>   elfcorehdr_addr != ELFCORE_ADDR_MAX;

Agree. I fell into the blind corner of thinking earlier. Above change
is better.

> }
> 
> static inline void vmcore_unusable(void)
> {
>   elfcorehdr_addr = ELFCORE_ADDR_ERR;
> }
> 
> 
> Then all we need on powerpc is a way to override is_kdump_kernel().
> 
> cheers
> 


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Re: [PATCH v2 2/3] vmcore: allow fadump to export vmcore even if is_kdump_kernel() is false

2023-09-11 Thread Michael Ellerman 
Hari Bathini  writes:
> 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. Since, is_kdump_kernel() is used to restrict resources in
> crash dump capture kernel and such restrictions are not desirable for
> fadump, allow is_kdump_kernel() to be defined differently for fadump
> case. With that change, include is_fadump_active() check in functions
> is_vmcore_usable() & vmcore_unusable() to be able to export vmcore for
> fadump case too.
...
> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> index 0f3a656293b0..de8a9fabfb6f 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
> +
> +#ifndef is_fadump_active
> +/*
> + * If f/w assisted dump capturing mechanism (fadump), instead of kexec based
> + * dump capturing mechanism (kdump) is exporting the vmcore, then this 
> function
> + * will be defined in arch specific code to return true, when appropriate.
> + */
> +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 +89,8 @@ 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 +99,7 @@ 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;
>  }

I think it would be cleaner to decouple is_vmcore_usable() and
vmcore_usable() from is_kdump_kernel().

ie, make them operate solely based on the value of elforehdr_addr:

static inline int is_vmcore_usable(void)
{
elfcorehdr_addr != ELFCORE_ADDR_ERR && \
elfcorehdr_addr != ELFCORE_ADDR_MAX;
}

static inline void vmcore_unusable(void)
{
elfcorehdr_addr = ELFCORE_ADDR_ERR;
}


Then all we need on powerpc is a way to override is_kdump_kernel().

cheers

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[PATCH v2 2/3] vmcore: allow fadump to export vmcore even if is_kdump_kernel() is false

2023-09-05 Thread Hari Bathini 
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. Since, is_kdump_kernel() is used to restrict resources in
crash dump capture kernel and such restrictions are not desirable for
fadump, allow is_kdump_kernel() to be defined differently for fadump
case. With that change, include is_fadump_active() check in functions
is_vmcore_usable() & vmcore_unusable() to be able to export vmcore for
fadump case too.

[1] https://docs.kernel.org/powerpc/firmware-assisted-dump.html

Signed-off-by: Hari Bathini 
---

Changes in v2:
* is_fadump_active() check added to is_vmcore_usable() as suggested
  by Baoquan.


 include/linux/crash_dump.h | 19 +--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0f3a656293b0..de8a9fabfb6f 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
+
+#ifndef is_fadump_active
+/*
+ * If f/w assisted dump capturing mechanism (fadump), instead of kexec based
+ * dump capturing mechanism (kdump) is exporting the vmcore, then this function
+ * will be defined in arch specific code to return true, when appropriate.
+ */
+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 +89,8 @@ 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 +99,7 @@ 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;
 }
 
-- 
2.41.0


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