From 2edb16efc899f9c232e2d880930b855e4cf55df4 Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Fri, 26 Apr 2019 16:23:34 +0000
Subject: [PATCH] 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>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/kasan.h | 9 ++
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/init_32.c | 3 +
arch/powerpc/mm/kasan/kasan_init_32.c | 156 ++++++++++++++++++++++++++
11 files changed, 188 insertions(+)
create mode 100644 arch/powerpc/mm/kasan/kasan_init_32.c
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 515bd10d32f6d..2711aac24621b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -173,6 +173,7 @@ 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
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index 05274dea31091..296e51c2f066b 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -27,5 +27,14 @@
#define KASAN_SHADOW_SIZE (KASAN_SHADOW_END - KASAN_SHADOW_START)
+#ifdef CONFIG_KASAN
+void kasan_early_init(void);
+void kasan_mmu_init(void);
+void kasan_init(void);
+#else
+static inline void kasan_init(void) { }
+static inline void kasan_mmu_init(void) { }
+#endif
+
#endif /* __ASSEMBLY */
#endif
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 40aec3f00a052..6e85171e513c8 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -969,6 +969,9 @@ 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
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index a9c934f2319b5..efa219d2136e7 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -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
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 37117ab11584c..34a5df827b38e 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -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
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 03c73b4c64359..d25adb6ef2350 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -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
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 32332e24e4216..567e0ed45ca81 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -268,6 +268,9 @@ 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
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 19d68a9b5f372..91d2c6970bdb9 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -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"
@@ -871,6 +872,8 @@ 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 */
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 62735f335bce3..d8c0ce9b25576 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -26,3 +26,4 @@ obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o
obj-$(CONFIG_HIGHMEM) += highmem.o
obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o
obj-$(CONFIG_PPC_PTDUMP) += ptdump/
+obj-$(CONFIG_KASAN) += kasan/
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 3eb4cb09749c6..c3121b6c8cbdf 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -46,6 +46,7 @@
#include <asm/sections.h>
#include <asm/hugetlb.h>
#include <asm/kup.h>
+#include <asm/kasan.h>
#include <mm/mmu_decl.h>
@@ -179,6 +180,8 @@ void __init MMU_init(void)
btext_unmap();
#endif
+ kasan_mmu_init();
+
setup_kup();
/* Shortly after that, the entire linear mapping will be available */
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 0000000000000..42617fcad8289
--- /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");
+}
--
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