diff mbox series

[v3,1/2] vmcore: remove dependency with is_kdump_kernel() for exporting vmcore

Message ID 20230912082950.856977-1-hbathini@linux.ibm.com
State New
Headers
Series [v3,1/2] vmcore: remove dependency with is_kdump_kernel() for exporting vmcore |

Commit Message

Hari Bathini Sept. 12, 2023, 8:29 a.m. UTC 
  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 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, remove unnecessary dependency with is_kdump_kernel(), for
exporting vmcore.

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

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---

Changes in v3:
* Decoupled is_vmcore_usable() & vmcore_unusable() from is_kdump_kernel()
  as suggested here: 
    https://lore.kernel.org/linuxppc-dev/ZP7si3UMVpPfYV+w@MiWiFi-R3L-srv/T/#m13ae5a7e4ba6f4d8397f0f66581832292eee3a85


 include/linux/crash_dump.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Baoquan He Sept. 14, 2023, 4:40 a.m. UTC | #1 
On 09/12/23 at 01:59pm, 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. Since, is_kdump_kernel() is used to restrict resources in
> crash dump capture kernel and 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, remove unnecessary dependency with is_kdump_kernel(), for
> exporting vmcore.
> 
> [1] https://docs.kernel.org/powerpc/firmware-assisted-dump.html
> 
> Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
> ---
> 
> Changes in v3:
> * Decoupled is_vmcore_usable() & vmcore_unusable() from is_kdump_kernel()
>   as suggested here: 
>     https://lore.kernel.org/linuxppc-dev/ZP7si3UMVpPfYV+w@MiWiFi-R3L-srv/T/#m13ae5a7e4ba6f4d8397f0f66581832292eee3a85
> 
> 
>  include/linux/crash_dump.h | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

LGTM,

Acked-by: Baoquan He <bhe@redhat.com>

> 
> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> index 0f3a656293b0..acc55626afdc 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 +65,7 @@ static inline bool is_kdump_kernel(void)
>  {
>  	return elfcorehdr_addr != ELFCORE_ADDR_MAX;
>  }
> +#endif
>  
>  /* is_vmcore_usable() checks if the kernel is booting after a panic and
>   * the vmcore region is usable.
> @@ -75,7 +77,8 @@ 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 elfcorehdr_addr != ELFCORE_ADDR_ERR &&
> +		elfcorehdr_addr != ELFCORE_ADDR_MAX ? 1 : 0;
>  }
>  
>  /* vmcore_unusable() marks the vmcore as unusable,
> @@ -84,8 +87,7 @@ static inline int is_vmcore_usable(void)
>  
>  static inline void vmcore_unusable(void)
>  {
> -	if (is_kdump_kernel())
> -		elfcorehdr_addr = ELFCORE_ADDR_ERR;
> +	elfcorehdr_addr = ELFCORE_ADDR_ERR;
>  }
>  
>  /**
> -- 
> 2.41.0
>
Michael Ellerman Sept. 21, 2023, 9:30 a.m. UTC | #2 
On Tue, 12 Sep 2023 13:59:49 +0530, 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. Since, is_kdump_kernel() is used to restrict resources in
> crash dump capture kernel and 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, remove unnecessary dependency with is_kdump_kernel(), for
> exporting vmcore.
> 
> [...]

Applied to powerpc/next.

[1/2] vmcore: remove dependency with is_kdump_kernel() for exporting vmcore
      https://git.kernel.org/powerpc/c/86328b338c3996b814417dd68e3f899a1a649059
[2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active
      https://git.kernel.org/powerpc/c/b098f1c32365304633077d73e4ae21c72d4241b3

cheers
diff mbox series

Patch

diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0f3a656293b0..acc55626afdc 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 +65,7 @@  static inline bool is_kdump_kernel(void)
 {
 	return elfcorehdr_addr != ELFCORE_ADDR_MAX;
 }
+#endif
 
 /* is_vmcore_usable() checks if the kernel is booting after a panic and
  * the vmcore region is usable.
@@ -75,7 +77,8 @@  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 elfcorehdr_addr != ELFCORE_ADDR_ERR &&
+		elfcorehdr_addr != ELFCORE_ADDR_MAX ? 1 : 0;
 }
 
 /* vmcore_unusable() marks the vmcore as unusable,
@@ -84,8 +87,7 @@  static inline int is_vmcore_usable(void)
 
 static inline void vmcore_unusable(void)
 {
-	if (is_kdump_kernel())
-		elfcorehdr_addr = ELFCORE_ADDR_ERR;
+	elfcorehdr_addr = ELFCORE_ADDR_ERR;
 }
 
 /**