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 <[email protected]>
Signed-off-by: Hari Bathini <[email protected]>
---
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(-)
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
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 dump is active.
Signed-off-by: Hari Bathini <[email protected]>
---
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
On 09/12/23 at 01:59pm, Hari Bathini wrote:
> 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 dump is active.
>
> Signed-off-by: Hari Bathini <[email protected]>
> ---
> arch/powerpc/include/asm/kexec.h | 8 ++++++--
> arch/powerpc/kernel/crash_dump.c | 12 ++++++++++++
> 2 files changed, 18 insertions(+), 2 deletions(-)
LGTM,
Acked-by: Baoquan He <[email protected]>
>
> 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
>
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 <[email protected]>
> Signed-off-by: Hari Bathini <[email protected]>
> ---
>
> 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 <[email protected]>
>
> 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
>
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