| Message ID | 20211012011350.395767-1-joel@jms.id.au (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/s64: Clarify that radix lacks DEBUG_PAGEALLOC | expand |
| Related | show |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | warning | Found 80 issues from 8 of 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | warning | Found 160 issues from 8 of 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | warning | Found 125 issues from 4 of 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | warning | Found 7 issues from 3 of 7 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
Le 12/10/2021 à 03:13, Joel Stanley a écrit : > 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> > --- > I noticed this when I was looking at adding kfence support a while back. > I've put that work aside and jpn has since gotten further than me, but I > think this is a fix worth considering. > > arch/powerpc/include/asm/book3s/64/hash.h | 2 ++ > arch/powerpc/mm/book3s64/hash_utils.c | 2 +- > arch/powerpc/mm/book3s64/pgtable.c | 12 ++++++++++++ > 3 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h > index d959b0195ad9..674fe0e890dc 100644 > --- a/arch/powerpc/include/asm/book3s/64/hash.h > +++ b/arch/powerpc/include/asm/book3s/64/hash.h > @@ -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 */ > diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c > index c145776d3ae5..cfd45245d009 100644 > --- a/arch/powerpc/mm/book3s64/hash_utils.c > +++ b/arch/powerpc/mm/book3s64/hash_utils.c > @@ -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; > diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c > index 9e16c7b1a6c5..0aefc272cd03 100644 > --- a/arch/powerpc/mm/book3s64/pgtable.c > +++ b/arch/powerpc/mm/book3s64/pgtable.c > @@ -526,3 +526,15 @@ static int __init pgtable_debugfs_setup(void) > return 0; > } > arch_initcall(pgtable_debugfs_setup); > + > +#ifdef CONFIG_DEBUG_PAGEALLOC > +void __kernel_map_pages(struct page *page, int numpages, int enable) > +{ > + if (radix_enabled()) { > + pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n"); > + return; > + } > + > + hash__kernel_map_pages(page, numpages, enable); > +} I think it would be better to do similar to most other functions (like map_kernel_page() for instance): In arch/powerpc/include/asm/book3s/64/pgtable.h do: static inline void __kernel_map_pages(struct page *page, int numpages, int enable) { if (radix_enabled()) radix__kernel_map_pages(...); else hash__kernel_map_pages(...); } Then in arch/powerpc/include/asm/book3s/64/radix.h do (or in /arch/powerpc/mm/book3s64/radix_pgtable.c in you prefer ?): static inline void radix__kernel_map_pages(struct page *page, int numpages, int enable) { pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n"); } > +#endif >
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h index d959b0195ad9..674fe0e890dc 100644 --- a/arch/powerpc/include/asm/book3s/64/hash.h +++ b/arch/powerpc/include/asm/book3s/64/hash.h @@ -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 */ diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index c145776d3ae5..cfd45245d009 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -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; diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c index 9e16c7b1a6c5..0aefc272cd03 100644 --- a/arch/powerpc/mm/book3s64/pgtable.c +++ b/arch/powerpc/mm/book3s64/pgtable.c @@ -526,3 +526,15 @@ static int __init pgtable_debugfs_setup(void) return 0; } arch_initcall(pgtable_debugfs_setup); + +#ifdef CONFIG_DEBUG_PAGEALLOC +void __kernel_map_pages(struct page *page, int numpages, int enable) +{ + if (radix_enabled()) { + pr_warn_once("DEBUG_PAGEALLOC not supported in radix mode\n"); + return; + } + + hash__kernel_map_pages(page, numpages, enable); +} +#endif
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> --- I noticed this when I was looking at adding kfence support a while back. I've put that work aside and jpn has since gotten further than me, but I think this is a fix worth considering. arch/powerpc/include/asm/book3s/64/hash.h | 2 ++ arch/powerpc/mm/book3s64/hash_utils.c | 2 +- arch/powerpc/mm/book3s64/pgtable.c | 12 ++++++++++++ 3 files changed, 15 insertions(+), 1 deletion(-)