[RFC v1 08/10] book3s64/hash: Add kfence functionality
Ritesh Harjani (IBM)
ritesh.list at gmail.com
Wed Jul 31 17:56:12 AEST 2024
Now that linear map functionality of debug_pagealloc is made generic,
enable kfence to use this generic infrastructure.
1. Define kfence related linear map variables.
- u8 *linear_map_kf_hash_slots;
- unsigned long linear_map_kf_hash_count;
- DEFINE_RAW_SPINLOCK(linear_map_kf_hash_lock);
2. The linear map size allocated in RMA region is quite small
(KFENCE_POOL_SIZE >> PAGE_SHIFT) which is 512 bytes by default.
3. kfence pool memory is reserved using memblock_phys_alloc() which has
can come from anywhere.
(default 255 objects => ((1+255) * 2) << PAGE_SHIFT = 32MB)
4. The hash slot information for kfence memory gets added in linear map
in hash_linear_map_add_slot() (which also adds for debug_pagealloc).
Reported-by: Pavithra Prakash <pavrampu at linux.vnet.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list at gmail.com>
---
arch/powerpc/include/asm/kfence.h | 5 -
arch/powerpc/mm/book3s64/hash_utils.c | 162 +++++++++++++++++++++++---
2 files changed, 149 insertions(+), 18 deletions(-)
diff --git a/arch/powerpc/include/asm/kfence.h b/arch/powerpc/include/asm/kfence.h
index f3a9476a71b3..fab124ada1c7 100644
--- a/arch/powerpc/include/asm/kfence.h
+++ b/arch/powerpc/include/asm/kfence.h
@@ -10,7 +10,6 @@
#include <linux/mm.h>
#include <asm/pgtable.h>
-#include <asm/mmu.h>
#ifdef CONFIG_PPC64_ELF_ABI_V1
#define ARCH_FUNC_PREFIX "."
@@ -26,10 +25,6 @@ static inline void disable_kfence(void)
static inline bool arch_kfence_init_pool(void)
{
-#ifdef CONFIG_PPC64
- if (!radix_enabled())
- return false;
-#endif
return !kfence_disabled;
}
#endif
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 906cd167180a..c66b9921fc7d 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -40,6 +40,7 @@
#include <linux/random.h>
#include <linux/elf-randomize.h>
#include <linux/of_fdt.h>
+#include <linux/kfence.h>
#include <asm/interrupt.h>
#include <asm/processor.h>
@@ -66,6 +67,7 @@
#include <asm/pte-walk.h>
#include <asm/asm-prototypes.h>
#include <asm/ultravisor.h>
+#include <asm/kfence.h>
#include <mm/mmu_decl.h>
@@ -271,7 +273,7 @@ void hash__tlbiel_all(unsigned int action)
WARN(1, "%s called on pre-POWER7 CPU\n", __func__);
}
-#if defined(CONFIG_DEBUG_PAGEALLOC)
+#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
static void kernel_map_linear_page(unsigned long vaddr, unsigned long idx,
u8 *slots, raw_spinlock_t *lock)
{
@@ -325,11 +327,13 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long idx,
mmu_linear_psize,
mmu_kernel_ssize, 0);
}
+#endif
+#if defined(CONFIG_DEBUG_PAGEALLOC)
static u8 *linear_map_hash_slots;
static unsigned long linear_map_hash_count;
static DEFINE_RAW_SPINLOCK(linear_map_hash_lock);
-static inline void hash_debug_pagealloc_alloc_slots(void)
+static void hash_debug_pagealloc_alloc_slots(void)
{
unsigned long max_hash_count = (ppc64_rma_size / 4) >> PAGE_SHIFT;
@@ -352,7 +356,8 @@ static inline void hash_debug_pagealloc_alloc_slots(void)
__func__, linear_map_hash_count, &ppc64_rma_size);
}
-static inline void hash_debug_pagealloc_add_slot(phys_addr_t paddr, int slot)
+static inline void hash_debug_pagealloc_add_slot(phys_addr_t paddr,
+ int slot)
{
if (!debug_pagealloc_enabled() || !linear_map_hash_count)
return;
@@ -386,20 +391,148 @@ static int hash_debug_pagealloc_map_pages(struct page *page, int numpages,
return 0;
}
-int hash__kernel_map_pages(struct page *page, int numpages, int enable)
+#else /* CONFIG_DEBUG_PAGEALLOC */
+static inline void hash_debug_pagealloc_alloc_slots(void) {}
+static inline void hash_debug_pagealloc_add_slot(phys_addr_t paddr, int slot) {}
+static int __maybe_unused
+hash_debug_pagealloc_map_pages(struct page *page, int numpages, int enable)
{
- return hash_debug_pagealloc_map_pages(page, numpages, enable);
+ return 0;
}
+#endif /* CONFIG_DEBUG_PAGEALLOC */
-#else /* CONFIG_DEBUG_PAGEALLOC */
-int hash__kernel_map_pages(struct page *page, int numpages,
- int enable)
+#if defined(CONFIG_KFENCE)
+static u8 *linear_map_kf_hash_slots;
+static unsigned long linear_map_kf_hash_count;
+static DEFINE_RAW_SPINLOCK(linear_map_kf_hash_lock);
+
+static phys_addr_t kfence_pool;
+
+static inline void hash_kfence_alloc_pool(void)
+{
+
+ // allocate linear map for kfence within RMA region
+ linear_map_kf_hash_count = KFENCE_POOL_SIZE >> PAGE_SHIFT;
+ linear_map_kf_hash_slots = memblock_alloc_try_nid(
+ linear_map_kf_hash_count, 1,
+ MEMBLOCK_LOW_LIMIT, ppc64_rma_size,
+ NUMA_NO_NODE);
+ if (!linear_map_kf_hash_slots) {
+ pr_err("%s: memblock for linear map (%lu) failed\n", __func__,
+ linear_map_kf_hash_count);
+ goto err;
+ }
+
+ // allocate kfence pool early
+ kfence_pool = memblock_phys_alloc_range(KFENCE_POOL_SIZE, PAGE_SIZE,
+ MEMBLOCK_LOW_LIMIT, MEMBLOCK_ALLOC_ANYWHERE);
+ if (!kfence_pool) {
+ pr_err("%s: memblock for kfence pool (%lu) failed\n", __func__,
+ KFENCE_POOL_SIZE);
+ memblock_free(linear_map_kf_hash_slots,
+ linear_map_kf_hash_count);
+ linear_map_kf_hash_count = 0;
+ goto err;
+ }
+ memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
+
+ return;
+err:
+ pr_info("Disabling kfence\n");
+ disable_kfence();
+}
+
+static inline void hash_kfence_map_pool(void)
+{
+ unsigned long kfence_pool_start, kfence_pool_end;
+ unsigned long prot = pgprot_val(PAGE_KERNEL);
+
+ if (!kfence_pool)
+ return;
+
+ kfence_pool_start = (unsigned long) __va(kfence_pool);
+ kfence_pool_end = kfence_pool_start + KFENCE_POOL_SIZE;
+ __kfence_pool = (char *) kfence_pool_start;
+ BUG_ON(htab_bolt_mapping(kfence_pool_start, kfence_pool_end,
+ kfence_pool, prot, mmu_linear_psize,
+ mmu_kernel_ssize));
+ memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
+}
+
+static inline void hash_kfence_add_slot(phys_addr_t paddr, int slot)
{
+ unsigned long vaddr = (unsigned long) __va(paddr);
+ unsigned long lmi = (vaddr - (unsigned long)__kfence_pool)
+ >> PAGE_SHIFT;
+
+ if (!kfence_pool)
+ return;
+ BUG_ON(!is_kfence_address((void *)vaddr));
+ BUG_ON(lmi >= linear_map_kf_hash_count);
+ linear_map_kf_hash_slots[lmi] = slot | 0x80;
+}
+
+static int hash_kfence_map_pages(struct page *page, int numpages, int enable)
+{
+ unsigned long flags, vaddr, lmi;
+ int i;
+
+ WARN_ON_ONCE(!linear_map_kf_hash_count);
+ local_irq_save(flags);
+ for (i = 0; i < numpages; i++, page++) {
+ vaddr = (unsigned long)page_address(page);
+ lmi = (vaddr - (unsigned long)__kfence_pool) >> PAGE_SHIFT;
+
+ /* Ideally this should never happen */
+ if (lmi >= linear_map_kf_hash_count) {
+ WARN_ON_ONCE(1);
+ continue;
+ }
+
+ if (enable)
+ kernel_map_linear_page(vaddr, lmi,
+ linear_map_kf_hash_slots,
+ &linear_map_kf_hash_lock);
+ else
+ kernel_unmap_linear_page(vaddr, lmi,
+ linear_map_kf_hash_slots,
+ &linear_map_kf_hash_lock);
+ }
+ local_irq_restore(flags);
return 0;
}
-static inline void hash_debug_pagealloc_alloc_slots(void) {}
-static inline void hash_debug_pagealloc_add_slot(phys_addr_t paddr, int slot) {}
-#endif /* CONFIG_DEBUG_PAGEALLOC */
+#else
+static inline void hash_kfence_alloc_pool(void) {}
+static inline void hash_kfence_map_pool(void) {}
+static inline void hash_kfence_add_slot(phys_addr_t paddr, int slot) {}
+static int __maybe_unused
+hash_kfence_map_pages(struct page *page, int numpages, int enable)
+{
+ return 0;
+}
+#endif
+
+#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
+int hash__kernel_map_pages(struct page *page, int numpages, int enable)
+{
+ void *vaddr = page_address(page);
+
+ if (is_kfence_address(vaddr))
+ return hash_kfence_map_pages(page, numpages, enable);
+ else
+ return hash_debug_pagealloc_map_pages(page, numpages, enable);
+}
+
+static void hash_linear_map_add_slot(phys_addr_t paddr, int slot)
+{
+ if (is_kfence_address(__va(paddr)))
+ hash_kfence_add_slot(paddr, slot);
+ else
+ hash_debug_pagealloc_add_slot(paddr, slot);
+}
+#else
+static void hash_linear_map_add_slot(phys_addr_t paddr, int slot) {}
+#endif
/*
* 'R' and 'C' update notes:
@@ -559,7 +692,8 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
break;
cond_resched();
- hash_debug_pagealloc_add_slot(paddr, ret);
+ // add slot info in debug_pagealloc / kfence linear map
+ hash_linear_map_add_slot(paddr, ret);
}
return ret < 0 ? ret : 0;
}
@@ -940,7 +1074,7 @@ 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
@@ -1261,6 +1395,7 @@ static void __init htab_initialize(void)
prot = pgprot_val(PAGE_KERNEL);
hash_debug_pagealloc_alloc_slots();
+ hash_kfence_alloc_pool();
/* create bolted the linear mapping in the hash table */
for_each_mem_range(i, &base, &end) {
size = end - base;
@@ -1277,6 +1412,7 @@ static void __init htab_initialize(void)
BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
prot, mmu_linear_psize, mmu_kernel_ssize));
}
+ hash_kfence_map_pool();
memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
/*
--
2.45.2
More information about the Linuxppc-dev
mailing list