Le 19/09/2022 à 03:44, Nicholas Miehlbradt a écrit :
> KFENCE support was added for ppc32 in commit 90cbac0e995d
> ("powerpc: Enable KFENCE for PPC32").
> Enable KFENCE on ppc64 architecture with hash and radix MMUs.
> It uses the same mechanism as debug pagealloc to
> protect/unprotect pages. All KFENCE kunit tests pass on both
> MMUs.
>
> KFENCE memory is initially allocated using memblock but is
> later marked as SLAB allocated. This necessitates the change
> to __pud_free to ensure that the KFENCE pages are freed
> appropriately.
>
> Based on previous work by Christophe Leroy and Jordan Niethe.
>
> Signed-off-by: Nicholas Miehlbradt <nicho...@linux.ibm.com>
> ---
> arch/powerpc/Kconfig | 2 +-
> arch/powerpc/include/asm/book3s/64/pgalloc.h | 6 ++++--
> arch/powerpc/include/asm/book3s/64/pgtable.h | 2 +-
> arch/powerpc/include/asm/kfence.h | 18 ++++++++++++++++++
> arch/powerpc/mm/book3s64/hash_utils.c | 10 +++++-----
> arch/powerpc/mm/book3s64/radix_pgtable.c | 8 +++++---
> 6 files changed, 34 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index a4f8a5276e5c..f7dd0f49510d 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -194,7 +194,7 @@ config PPC
> select HAVE_ARCH_KASAN if PPC32 && PPC_PAGE_SHIFT <= 14
> select HAVE_ARCH_KASAN if PPC_RADIX_MMU
> select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
> - select HAVE_ARCH_KFENCE if PPC_BOOK3S_32 || PPC_8xx ||
> 40x
> + select HAVE_ARCH_KFENCE if ARCH_SUPPORTS_DEBUG_PAGEALLOC
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_MMAP_RND_BITS
> select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
> diff --git a/arch/powerpc/include/asm/book3s/64/pgalloc.h
> b/arch/powerpc/include/asm/book3s/64/pgalloc.h
> index e1af0b394ceb..dd2cff53a111 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgalloc.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h
> @@ -113,9 +113,11 @@ static inline void __pud_free(pud_t *pud)
>
> /*
> * Early pud pages allocated via memblock allocator
> - * can't be directly freed to slab
> + * can't be directly freed to slab. KFENCE pages have
> + * both reserved and slab flags set so need to be freed
> + * kmem_cache_free.
> */
> - if (PageReserved(page))
> + if (PageReserved(page) && !PageSlab(page))
> free_reserved_page(page);
> else
> kmem_cache_free(PGT_CACHE(PUD_CACHE_INDEX), pud);
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h
> b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index cb9d5fd39d7f..fd5d800f2836 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -1123,7 +1123,7 @@ static inline void vmemmap_remove_mapping(unsigned long
> start,
> }
> #endif
>
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> +#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
> static inline void __kernel_map_pages(struct page *page, int numpages, int
> enable)
> {
> if (radix_enabled())
> diff --git a/arch/powerpc/include/asm/kfence.h
> b/arch/powerpc/include/asm/kfence.h
> index a9846b68c6b9..33edbc312a51 100644
> --- a/arch/powerpc/include/asm/kfence.h
> +++ b/arch/powerpc/include/asm/kfence.h
> @@ -11,11 +11,28 @@
> #include <linux/mm.h>
> #include <asm/pgtable.h>
>
> +#if defined(CONFIG_PPC64) && !defined(CONFIG_PPC64_ELF_ABI_V2)
Can be replaced by:
#ifdef CONFIG_PPC64_ELF_ABI_V1
> +#define ARCH_FUNC_PREFIX "."
> +#endif
> +
> static inline bool arch_kfence_init_pool(void)
> {
> return true;
> }
>
> +#ifdef CONFIG_PPC64
> +static inline bool kfence_protect_page(unsigned long addr, bool protect)
> +{
> + struct page *page = virt_to_page(addr);
> +
> + if (protect)
> + __kernel_map_pages(page, 1, 0);
> + else
> + __kernel_map_pages(page, 1, 1);
Can be:
__kernel_map_pages(virt_to_page(addr), !protect);
> +
> + return true;
> +}
> +#else
> static inline bool kfence_protect_page(unsigned long addr, bool protect)
> {
> pte_t *kpte = virt_to_kpte(addr);
> @@ -29,5 +46,6 @@ static inline bool kfence_protect_page(unsigned long addr,
> bool protect)
>
> return true;
> }
> +#endif
>
> #endif /* __ASM_POWERPC_KFENCE_H */
> diff --git a/arch/powerpc/mm/book3s64/hash_utils.c
> b/arch/powerpc/mm/book3s64/hash_utils.c
> index b37412fe5930..9cceaa5998a3 100644
> --- a/arch/powerpc/mm/book3s64/hash_utils.c
> +++ b/arch/powerpc/mm/book3s64/hash_utils.c
> @@ -424,7 +424,7 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long
> vend,
> break;
>
> cond_resched();
> - if (debug_pagealloc_enabled() &&
> + if (debug_pagealloc_enabled_or_kfence() &&
> (paddr >> PAGE_SHIFT) < linear_map_hash_count)
> linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80;
> }
> @@ -773,7 +773,7 @@ static void __init htab_init_page_sizes(void)
> bool aligned = true;
> init_hpte_page_sizes();
>
> - if (!debug_pagealloc_enabled()) {
> + if (!debug_pagealloc_enabled_or_kfence()) {
> /*
> * Pick a size for the linear mapping. Currently, we only
> * support 16M, 1M and 4K which is the default
> @@ -1061,7 +1061,7 @@ static void __init htab_initialize(void)
>
> prot = pgprot_val(PAGE_KERNEL);
>
> - if (debug_pagealloc_enabled()) {
> + if (debug_pagealloc_enabled_or_kfence()) {
> linear_map_hash_count = memblock_end_of_DRAM() >> PAGE_SHIFT;
> linear_map_hash_slots = memblock_alloc_try_nid(
> linear_map_hash_count, 1, MEMBLOCK_LOW_LIMIT,
> @@ -1983,7 +1983,7 @@ long hpte_insert_repeating(unsigned long hash, unsigned
> long vpn,
> return slot;
> }
>
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> +#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
> static DEFINE_SPINLOCK(linear_map_hash_lock);
>
> static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
> @@ -2056,7 +2056,7 @@ void hash__kernel_map_pages(struct page *page, int
> numpages, int enable)
> }
> local_irq_restore(flags);
> }
> -#endif /* CONFIG_DEBUG_PAGEALLOC */
> +#endif /* CONFIG_DEBUG_PAGEALLOC || CONFIG_KFENCE */
>
> void hash__setup_initial_memory_limit(phys_addr_t first_memblock_base,
> phys_addr_t first_memblock_size)
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c
> b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 483c99bfbde5..217833fe4f34 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -34,6 +34,8 @@
>
> #include <trace/events/thp.h>
>
> +#include <mm/mmu_decl.h>
> +
> unsigned int mmu_base_pid;
> unsigned long radix_mem_block_size __ro_after_init;
>
> @@ -504,7 +506,7 @@ static unsigned long __init radix_memory_block_size(void)
> {
> unsigned long mem_block_size = MIN_MEMORY_BLOCK_SIZE;
>
> - if (debug_pagealloc_enabled())
> + if (debug_pagealloc_enabled_or_kfence())
> return PAGE_SIZE;
>
> /*
> @@ -523,7 +525,7 @@ static unsigned long __init radix_memory_block_size(void)
>
> static unsigned long __init radix_memory_block_size(void)
> {
> - if (debug_pagealloc_enabled())
> + if (debug_pagealloc_enabled_or_kfence())
> return PAGE_SIZE;
>
> return 1UL * 1024 * 1024 * 1024;
> @@ -903,7 +905,7 @@ void __meminit radix__vmemmap_remove_mapping(unsigned
> long start, unsigned long
> #endif
> #endif
>
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> +#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
> void radix__kernel_map_pages(struct page *page, int numpages, int enable)
> {
> unsigned long addr;
