[PATCH v3 4/4] powerpc/64s: Enable KFENCE on book3s64
Nicholas Miehlbradt
nicholas at linux.ibm.com
Mon Sep 26 17:57:26 AEST 2022
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 <nicholas at linux.ibm.com>
---
v2: Refactor
v3: Simplified ABI version check
---
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 | 15 +++++++++++++++
arch/powerpc/mm/book3s64/hash_utils.c | 10 +++++-----
arch/powerpc/mm/book3s64/radix_pgtable.c | 6 ++++--
6 files changed, 30 insertions(+), 11 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..6fd2b4d486c5 100644
--- a/arch/powerpc/include/asm/kfence.h
+++ b/arch/powerpc/include/asm/kfence.h
@@ -11,11 +11,25 @@
#include <linux/mm.h>
#include <asm/pgtable.h>
+#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);
+
+ __kernel_map_pages(page, 1, !protect);
+
+ return true;
+}
+#else
static inline bool kfence_protect_page(unsigned long addr, bool protect)
{
pte_t *kpte = virt_to_kpte(addr);
@@ -29,5 +43,6 @@ 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 daa40e3b74dd..6e4c2ca980ad 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;
@@ -276,7 +278,7 @@ static int __meminit create_physical_mapping(unsigned long start,
int psize;
unsigned long max_mapping_size = radix_mem_block_size;
- if (debug_pagealloc_enabled())
+ if (debug_pagealloc_enabled_or_kfence())
max_mapping_size = PAGE_SIZE;
start = ALIGN(start, PAGE_SIZE);
@@ -899,7 +901,7 @@ 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;
--
2.34.1
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