@@ -172,6 +172,7 @@ config PPC
select GENERIC_TIME_VSYSCALL
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
+ select HAVE_ARCH_KASAN if PPC32
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
@@ -27,5 +27,12 @@
#define KASAN_SHADOW_SIZE (KASAN_SHADOW_END - KASAN_SHADOW_START)
+#ifdef CONFIG_KASAN
+void kasan_early_init(void);
+void kasan_init(void);
+#else
+static inline void kasan_init(void) { }
+#endif
+
#endif /* __ASSEMBLY */
#endif
@@ -952,6 +952,9 @@ start_here:
* Do early platform-specific initialization,
* and set up the MMU.
*/
+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
li r3,0
mr r4,r31
bl machine_init
@@ -848,6 +848,9 @@ start_here:
/*
* Decide what sort of machine this is and initialize the MMU.
*/
+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
li r3,0
mr r4,r31
bl machine_init
@@ -203,6 +203,9 @@ _ENTRY(_start);
/*
* Decide what sort of machine this is and initialize the MMU.
*/
+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
li r3,0
mr r4,r31
bl machine_init
@@ -853,6 +853,9 @@ start_here:
/*
* Decide what sort of machine this is and initialize the MMU.
*/
+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
li r3,0
mr r4,r31
bl machine_init
@@ -275,6 +275,9 @@ set_ivor:
/*
* Decide what sort of machine this is and initialize the MMU.
*/
+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
mr r3,r30
mr r4,r31
bl machine_init
@@ -67,6 +67,7 @@
#include <asm/livepatch.h>
#include <asm/mmu_context.h>
#include <asm/cpu_has_feature.h>
+#include <asm/kasan.h>
#include "setup.h"
@@ -865,6 +866,8 @@ static void smp_setup_pacas(void)
*/
void __init setup_arch(char **cmdline_p)
{
+ kasan_init();
+
*cmdline_p = boot_command_line;
/* Set a half-reasonable default so udelay does something sensible */
@@ -53,6 +53,7 @@ obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o
obj-$(CONFIG_SPAPR_TCE_IOMMU) += mmu_context_iommu.o
obj-$(CONFIG_PPC_PTDUMP) += ptdump/
obj-$(CONFIG_PPC_MEM_KEYS) += pkeys.o
+obj-$(CONFIG_KASAN) += kasan/
# Disable kcov instrumentation on sensitive code
# This is necessary for booting with kcov enabled on book3e machines
new file mode 100644
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+KASAN_SANITIZE := n
+
+obj-$(CONFIG_PPC32) += kasan_init_32.o
new file mode 100644
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/printk.h>
+#include <linux/memblock.h>
+#include <linux/sched/task.h>
+#include <linux/vmalloc.h>
+#include <asm/pgalloc.h>
+#include <asm/code-patching.h>
+#include <mm/mmu_decl.h>
+
+static void kasan_populate_pte(pte_t *ptep, pgprot_t prot)
+{
+ phys_addr_t pa = __pa(kasan_early_shadow_page);
+ int i;
+
+ for (i = 0; i < PTRS_PER_PTE; i++, ptep++)
+ __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
+ ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
+}
+
+static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_end)
+{
+ pmd_t *pmd;
+ unsigned long k_cur, k_next;
+
+ pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
+
+ for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
+ pte_t *new;
+
+ k_next = pgd_addr_end(k_cur, k_end);
+ if ((void *)pmd_page_vaddr(*pmd) != kasan_early_shadow_pte)
+ continue;
+
+ new = pte_alloc_one_kernel(&init_mm);
+
+ if (!new)
+ return -ENOMEM;
+ kasan_populate_pte(new, PAGE_KERNEL_RO);
+ pmd_populate_kernel(&init_mm, pmd, new);
+ }
+ return 0;
+}
+
+static void __ref *kasan_get_one_page(void)
+{
+ if (slab_is_available())
+ return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+
+ return memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+}
+
+static int __ref kasan_init_region(void *start, size_t size)
+{
+ unsigned long k_start = (unsigned long)kasan_mem_to_shadow(start);
+ unsigned long k_end = (unsigned long)kasan_mem_to_shadow(start + size);
+ unsigned long k_cur;
+ pmd_t *pmd;
+ void *block = NULL;
+ int ret = kasan_init_shadow_page_tables(k_start, k_end);
+
+ if (ret)
+ return ret;
+
+ if (!slab_is_available())
+ block = memblock_alloc(k_end - k_start, PAGE_SIZE);
+
+ for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
+ void *va = block ? block + k_cur - k_start :
+ kasan_get_one_page();
+ pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
+
+ if (!va)
+ return -ENOMEM;
+
+ pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
+ pte_update(pte_offset_kernel(pmd, k_cur), ~0, pte_val(pte));
+ }
+ flush_tlb_kernel_range(k_start, k_end);
+ return 0;
+}
+
+static void __init kasan_remap_early_shadow_ro(void)
+{
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
+ flush_tlb_mm(&init_mm);
+}
+
+void __init kasan_init(void)
+{
+ int ret;
+ struct memblock_region *reg;
+
+ for_each_memblock(memory, reg) {
+ phys_addr_t base = reg->base;
+ phys_addr_t top = min(base + reg->size, total_lowmem);
+
+ if (base >= top)
+ continue;
+
+ ret = kasan_init_region(__va(base), top - base);
+ if (ret)
+ panic("kasan: kasan_init_region() failed");
+ }
+
+ kasan_remap_early_shadow_ro();
+
+ clear_page(kasan_early_shadow_page);
+
+ /* At this point kasan is fully initialized. Enable error messages */
+ init_task.kasan_depth = 0;
+ pr_info("KASAN init done\n");
+}
+
+#ifdef CONFIG_MODULES
+void *module_alloc(unsigned long size)
+{
+ void *base = vmalloc_exec(size);
+
+ if (!base)
+ return NULL;
+
+ if (!kasan_init_region(base, size))
+ return base;
+
+ vfree(base);
+
+ return NULL;
+}
+#endif
+
+void __init kasan_early_init(void)
+{
+ unsigned long addr = KASAN_SHADOW_START;
+ unsigned long end = KASAN_SHADOW_END;
+ unsigned long next;
+ pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
+
+ BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK);
+
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL);
+
+ do {
+ next = pgd_addr_end(addr, end);
+ pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte);
+ } while (pmd++, addr = next, addr != end);
+
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ WARN(1, "KASAN not supported on hash 6xx");
+}
This patch adds KASAN support for PPC32. The following patch will add an early activation of hash table for book3s. Until then, a warning will be raised if trying to use KASAN on an hash 6xx. To support KASAN, this patch initialises that MMU mapings for accessing to the KASAN shadow area defined in a previous patch. An early mapping is set as soon as the kernel code has been relocated at its definitive place. Then the definitive mapping is set once paging is initialised. For modules, the shadow area is allocated at module_alloc(). Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/kasan.h | 7 ++ arch/powerpc/kernel/head_32.S | 3 + arch/powerpc/kernel/head_40x.S | 3 + arch/powerpc/kernel/head_44x.S | 3 + arch/powerpc/kernel/head_8xx.S | 3 + arch/powerpc/kernel/head_fsl_booke.S | 3 + arch/powerpc/kernel/setup-common.c | 3 + arch/powerpc/mm/Makefile | 1 + arch/powerpc/mm/kasan/Makefile | 5 ++ arch/powerpc/mm/kasan/kasan_init_32.c | 153 ++++++++++++++++++++++++++++++++++ 11 files changed, 185 insertions(+) create mode 100644 arch/powerpc/mm/kasan/Makefile create mode 100644 arch/powerpc/mm/kasan/kasan_init_32.c