summaryrefslogtreecommitdiff
path: root/arch/powerpc/mm/kasan
diff options
context:
space:
mode:
authorChristophe Leroy <christophe.leroy@c-s.fr>2019-04-26 19:23:34 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2019-05-02 18:20:26 +0300
commit2edb16efc899f9c232e2d880930b855e4cf55df4 (patch)
tree34a2191ff699b55042f7827d2e0bd0852b0d63f3 /arch/powerpc/mm/kasan
parentf072015c7b742c42aa5649d22f43163cd0eb7024 (diff)
downloadlinux-2edb16efc899f9c232e2d880930b855e4cf55df4.tar.xz
powerpc/32: Add KASAN support
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> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm/kasan')
-rw-r--r--arch/powerpc/mm/kasan/kasan_init_32.c156
1 files changed, 156 insertions, 0 deletions
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
new file mode 100644
index 000000000000..42617fcad828
--- /dev/null
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -0,0 +1,156 @@
+// 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)
+{
+ unsigned long va = (unsigned long)kasan_early_shadow_page;
+ 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, va, 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;
+ int ret;
+ void *block = NULL;
+
+ 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) {
+ pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
+ 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;
+
+ __set_pte_at(&init_mm, k_cur, pte_offset_kernel(pmd, k_cur), pte, 0);
+ }
+ 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_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
+}
+
+void __init kasan_mmu_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");
+ }
+}
+
+void __init kasan_init(void)
+{
+ 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(true, "KASAN not supported on hash 6xx");
+}