[PATCH v2 4/4] powerpc: Enable KFENCE on BOOK3S/64

[Christophe Leroy]

This reuses the DEBUG_PAGEALLOC logic.

Tested on qemu with ppc64_defconfig + CONFIG_KFENCE + CONFIG_KUNIT +
CONFIG_KFENCE_KUNIT_TEST.

Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
---
v2: New
---
 arch/powerpc/Kconfig                  |  2 +-
 arch/powerpc/include/asm/kfence.h     |  8 ++++++++
 arch/powerpc/mm/book3s64/hash_utils.c | 29 +++++++++++++++++++++------
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d46db0bfb998..67c47b60cc84 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,7 +185,7 @@ config PPC
 	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14
 	select HAVE_ARCH_KASAN_VMALLOC		if PPC32 && PPC_PAGE_SHIFT <= 14
 	select HAVE_ARCH_KGDB
-	select HAVE_ARCH_KFENCE			if PPC32
+	select HAVE_ARCH_KFENCE			if ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if COMPAT
 	select HAVE_ARCH_NVRAM_OPS
diff --git a/arch/powerpc/include/asm/kfence.h b/arch/powerpc/include/asm/kfence.h
index a9846b68c6b9..532cc1a92fa5 100644
--- a/arch/powerpc/include/asm/kfence.h
+++ b/arch/powerpc/include/asm/kfence.h
@@ -11,11 +11,18 @@
 #include <linux/mm.h>
 #include <asm/pgtable.h>
 
+#if defined(CONFIG_PPC64) && !defined(PPC64_ELF_ABI_v2)
+#define ARCH_FUNC_PREFIX "."
+#endif
+
 static inline bool arch_kfence_init_pool(void)
 {
 	return true;
 }
 
+#ifdef CONFIG_PPC64
+bool kfence_protect_page(unsigned long addr, bool protect);
+#else
 static inline bool kfence_protect_page(unsigned long addr, bool protect)
 {
 	pte_t *kpte = virt_to_kpte(addr);
@@ -29,5 +36,6 @@ 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 cb09a49be798..b967a6403e59 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -323,8 +323,8 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 			break;
 
 		cond_resched();
-		if (debug_pagealloc_enabled() &&
-			(paddr >> PAGE_SHIFT) < linear_map_hash_count)
+		if (debug_pagealloc_enabled_or_kfence() &&
+		    (paddr >> PAGE_SHIFT) < linear_map_hash_count)
 			linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80;
 	}
 	return ret < 0 ? ret : 0;
@@ -661,7 +661,7 @@ 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
@@ -949,7 +949,7 @@ 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,
@@ -1927,7 +1927,7 @@ 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)
@@ -1982,6 +1982,21 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
 				     mmu_kernel_ssize, 0);
 }
 
+#ifdef CONFIG_KFENCE
+bool kfence_protect_page(unsigned long addr, bool protect)
+{
+	unsigned long lmi = __pa(addr) >> PAGE_SHIFT;
+
+	if (protect)
+		kernel_unmap_linear_page(addr, lmi);
+	else
+		kernel_map_linear_page(addr, lmi);
+
+	return true;
+}
+#endif
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	unsigned long flags, vaddr, lmi;
@@ -2000,7 +2015,9 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 	}
 	local_irq_restore(flags);
 }
-#endif /* CONFIG_DEBUG_PAGEALLOC */
+#endif
+
+#endif /* CONFIG_DEBUG_PAGEALLOC || CONFIG_KFENCE */
 
 void hash__setup_initial_memory_limit(phys_addr_t first_memblock_base,
 				phys_addr_t first_memblock_size)
-- 
2.25.0