On Fri, Feb 23, 2024 at 03:54:12PM +0800, Baoquan He wrote:
> Add maintainer Kazu to CC.
Thanks, I missed him, will resend this patch with him in CC.
Thanks,
Aditya Gupta
>
> On 02/23/24 at 11:23am, Aditya Gupta wrote:
> > Currently makedumpfile depends on reading the 'cur_cpu_spec' kernel
> > symbol to get the current MMU type on PowerPC64.
> >
> > The disadvantage with this approach was that it depends on bit '0x40'
> > ('MMU_FTR_TYPE_RADIX') being set in 'cur_cpu_spec->mmu_features',
> > which implies kernel developers have to be careful of modifying
> > MMU_FTR_* defines
> >
> > Instead a more stable approach was suggested by contributors in
> > https://lore.kernel.org/linuxppc-dev/87v8c3m70t.fsf@mail.lhotse/, to
> > pass information about the MMU type in vmcoreinfo itself, instead of
> > depending on the MMU_FTR_* defines
> >
> > This was implemented in linux kernel in:
> > commit 36e826b568e4 ("powerpc/vmcore: Add MMU information to vmcoreinfo")
> >
> > With this commit, if RADIX_MMU is there in the vmcoreinfo, we prefer it
> > to get current mmu type, instead of 'cur_cpu_spec'.
> > On older kernels, where RADIX_MMU number is not there, makedumpfile will
> > simply fall back to using 'cur_cpu_spec'.
> >
> > The earlier defines for 'RADIX_MMU' have been renamed to 'MMU_TYPE_RADIX'
> > which avoids conflict with the vmcoreinfo string 'RADIX_MMU', as well as
> > being more clear about the value 0x40 with a comment about MMU_FTR_TYPE_RADIX
> >
> > Signed-off-by: Aditya Gupta <adityag@xxxxxxxxxxxxx>
> > ---
> > arch/ppc64.c | 15 ++++++++++-----
> > makedumpfile.c | 1 +
> > makedumpfile.h | 9 ++++++---
> > 3 files changed, 17 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/ppc64.c b/arch/ppc64.c
> > index 96c357cb0335..3b4f91981f71 100644
> > --- a/arch/ppc64.c
> > +++ b/arch/ppc64.c
> > @@ -250,7 +250,7 @@ ppc64_vmalloc_init(void)
> > /*
> > * 64K pagesize
> > */
> > - if (info->cur_mmu_type & RADIX_MMU) {
> > + if (info->cur_mmu_type & MMU_TYPE_RADIX) {
> > info->l1_index_size = PTE_INDEX_SIZE_RADIX_64K;
> > info->l2_index_size = PMD_INDEX_SIZE_RADIX_64K;
> > info->l3_index_size = PUD_INDEX_SIZE_RADIX_64K;
> > @@ -300,7 +300,7 @@ ppc64_vmalloc_init(void)
> > /*
> > * 4K pagesize
> > */
> > - if (info->cur_mmu_type & RADIX_MMU) {
> > + if (info->cur_mmu_type & MMU_TYPE_RADIX) {
> > info->l1_index_size = PTE_INDEX_SIZE_RADIX_4K;
> > info->l2_index_size = PMD_INDEX_SIZE_RADIX_4K;
> > info->l3_index_size = PUD_INDEX_SIZE_RADIX_4K;
> > @@ -635,14 +635,19 @@ get_versiondep_info_ppc64()
> > * On PowerISA 3.0 based server processors, a kernel can run with
> > * radix MMU or standard MMU. Get the current MMU type.
> > */
> > - info->cur_mmu_type = STD_MMU;
> > - if ((SYMBOL(cur_cpu_spec) != NOT_FOUND_SYMBOL)
> > + info->cur_mmu_type = MMU_TYPE_STD;
> > +
> > + if (NUMBER(RADIX_MMU) != NOT_FOUND_SYMBOL) {
> > + if (NUMBER(RADIX_MMU) == 1) {
> > + info->cur_mmu_type = MMU_TYPE_RADIX;
> > + }
> > + } else if ((SYMBOL(cur_cpu_spec) != NOT_FOUND_SYMBOL)
> > && (OFFSET(cpu_spec.mmu_features) != NOT_FOUND_STRUCTURE)) {
> > if (readmem(VADDR, SYMBOL(cur_cpu_spec), &cur_cpu_spec,
> > sizeof(cur_cpu_spec))) {
> > if (readmem(VADDR, cur_cpu_spec + OFFSET(cpu_spec.mmu_features),
> > &mmu_features, sizeof(mmu_features)))
> > - info->cur_mmu_type = mmu_features & RADIX_MMU;
> > + info->cur_mmu_type = mmu_features & MMU_TYPE_RADIX;
> > }
> > }
> >
> > diff --git a/makedumpfile.c b/makedumpfile.c
> > index 3705bdd93deb..1bd7305f49ca 100644
> > --- a/makedumpfile.c
> > +++ b/makedumpfile.c
> > @@ -2987,6 +2987,7 @@ read_vmcoreinfo(void)
> > #endif
> >
> > READ_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR);
> > + READ_NUMBER("RADIX_MMU", RADIX_MMU);
> >
> > return TRUE;
> > }
> > diff --git a/makedumpfile.h b/makedumpfile.h
> > index 3ed3ba551d96..a7b344974636 100644
> > --- a/makedumpfile.h
> > +++ b/makedumpfile.h
> > @@ -747,12 +747,13 @@ unsigned long get_kvbase_arm64(void);
> > /*
> > * Supported MMU types
> > */
> > -#define STD_MMU 0x0
> > +#define MMU_TYPE_STD 0x0
> > /*
> > * The flag bit for radix MMU in cpu_spec.mmu_features
> > - * in the kernel. Use the same flag here.
> > + * in the kernel (MMU_FTR_TYPE_RADIX).
> > + * Use the same flag here.
> > */
> > -#define RADIX_MMU 0x40
> > +#define MMU_TYPE_RADIX 0x40
> >
> >
> > #define PGD_MASK_L4 \
> > @@ -2258,6 +2259,8 @@ struct number_table {
> > unsigned long kernel_link_addr;
> > unsigned long va_kernel_pa_offset;
> > #endif
> > +
> > + unsigned long RADIX_MMU;
> > };
> >
> > struct srcfile_table {
> > --
> > 2.43.0
> >
> >
> > _______________________________________________
> > kexec mailing list
> > kexec@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/kexec
> >
>
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