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powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC

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The page_alloc.c code will call into __kernel_map_pages() when
DEBUG_PAGEALLOC is configured and enabled.

As the implementation assumes hash, this should crash spectacularly if
not for a bit of luck in __kernel_map_pages(). In this function
linear_map_hash_count is always zero, the for loop exits without doing
any damage.

There are no other platforms that determine if they support
debug_pagealloc at runtime. Instead of adding code to mm/page_alloc.c to
do that, this change turns the map/unmap into a noop when in radix
mode and prints a warning once.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Reformat if per Christophe's suggestion]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211013213438.675095-1-joel@jms.id.au
This commit is contained in:
Joel Stanley 2021-10-14 08:04:38 +10:30 committed by Michael Ellerman
parent 3091f5fc5f
commit 4f703e7faa
5 changed files with 23 additions and 1 deletions
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2
arch/powerpc/include/asm/book3s/64/hash.h
View file

@ -255,6 +255,8 @@ int hash__create_section_mapping(unsigned long start, unsigned long end,
int nid, pgprot_t prot);
int hash__remove_section_mapping(unsigned long start, unsigned long end);
void hash__kernel_map_pages(struct page *page, int numpages, int enable);
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */

10
arch/powerpc/include/asm/book3s/64/pgtable.h
View file

@ -1101,6 +1101,16 @@ static inline void vmemmap_remove_mapping(unsigned long start,
}
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
static inline void __kernel_map_pages(struct page *page, int numpages, int enable)
{
if (radix_enabled())
radix__kernel_map_pages(page, numpages, enable);
else
hash__kernel_map_pages(page, numpages, enable);
}
#endif
static inline pte_t pmd_pte(pmd_t pmd)
{
return __pte_raw(pmd_raw(pmd));

3
arch/powerpc/include/asm/book3s/64/radix.h
View file

@ -316,5 +316,8 @@ int radix__create_section_mapping(unsigned long start, unsigned long end,
int nid, pgprot_t prot);
int radix__remove_section_mapping(unsigned long start, unsigned long end);
#endif /* CONFIG_MEMORY_HOTPLUG */
void radix__kernel_map_pages(struct page *page, int numpages, int enable);
#endif /* __ASSEMBLY__ */
#endif

2
arch/powerpc/mm/book3s64/hash_utils.c
View file

@ -1988,7 +1988,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
mmu_kernel_ssize, 0);
}
void __kernel_map_pages(struct page *page, int numpages, int enable)
void hash__kernel_map_pages(struct page *page, int numpages, int enable)
{
unsigned long flags, vaddr, lmi;
int i;

7
arch/powerpc/mm/book3s64/radix_pgtable.c
View file

@ -920,6 +920,13 @@ void __meminit radix__vmemmap_remove_mapping(unsigned long start, unsigned long
#endif
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
void radix__kernel_map_pages(struct page *page, int numpages, int enable)
{
pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n");
}
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,