On 09/11/23 at 05:13pm, Michael Ellerman wrote:
> Hari Bathini <hbathini@xxxxxxxxxxxxx> 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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