[PATCH v1 6/6] powerpc/64e: KASAN Full support for BOOK3E/64

From: Christophe Leroy
Date: Tue Jun 28 2022 - 10:49:41 EST

We now have memory organised in a way that allows
implementing KASAN.

Unlike book3s/64, book3e always has translation active so the only
thing needed to use KASAN is to setup an early zero shadow mapping
just after setting a stack pointer and before calling early_setup().

The memory layout is now as follows

+------------------------+ Kernel virtual map end (0xc000200000000000)
| |
| 16TB of KASAN map |
| |
+------------------------+ Kernel KASAN shadow map start
| |
| 16TB of IO map |
| |
+------------------------+ Kernel IO map start
| |
| 16TB of vmemmap |
| |
+------------------------+ Kernel vmemmap start
| |
| 16TB of vmap |
| |
+------------------------+ Kernel virt start (0xc000100000000000)
| |
| 64TB of linear mem |
| |
+------------------------+ Kernel linear (0xc.....)

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/Kconfig | 2 +
arch/powerpc/Kconfig.debug | 3 +-
arch/powerpc/include/asm/kasan.h | 13 ++-
arch/powerpc/kernel/head_64.S | 3 +
arch/powerpc/mm/kasan/Makefile | 1 +
arch/powerpc/mm/kasan/init_book3e_64.c | 133 +++++++++++++++++++++++++
arch/powerpc/mm/kasan/init_book3s_64.c | 2 +
arch/powerpc/platforms/Kconfig.cputype | 1 -
8 files changed, 155 insertions(+), 3 deletions(-)
create mode 100644 arch/powerpc/mm/kasan/init_book3e_64.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c2ce2e60c8f0..92e0cad7752d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -193,6 +193,7 @@ config PPC
select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN if PPC32 && PPC_PAGE_SHIFT <= 14
select HAVE_ARCH_KASAN if PPC_RADIX_MMU
+ select HAVE_ARCH_KASAN if PPC_BOOK3E_64
select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
select HAVE_ARCH_KFENCE if PPC_BOOK3S_32 || PPC_8xx || 40x
select HAVE_ARCH_KGDB
@@ -254,6 +255,7 @@ config PPC
select IOMMU_HELPER if PPC64
select IRQ_DOMAIN
select IRQ_FORCED_THREADING
+ select KASAN_VMALLOC if KASAN && MODULES
select MMU_GATHER_PAGE_SIZE
select MMU_GATHER_RCU_TABLE_FREE
select MODULES_USE_ELF_RELA
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 9f363c143d86..6a8855d45af7 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -375,4 +375,5 @@ config KASAN_SHADOW_OFFSET
hex
depends on KASAN
default 0xe0000000 if PPC32
- default 0xa80e000000000000 if PPC64
+ default 0xa80e000000000000 if PPC_BOOK3S_64
+ default 0xa8001c0000000000 if PPC_BOOK3E_64
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index a6be4025cba2..92a968202ba7 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -19,7 +19,7 @@

#define KASAN_SHADOW_SCALE_SHIFT 3

-#ifdef CONFIG_MODULES
+#if defined(CONFIG_MODULES) && defined(CONFIG_PPC32)
#define KASAN_KERN_START ALIGN_DOWN(PAGE_OFFSET - SZ_256M, SZ_256M)
#else
#define KASAN_KERN_START PAGE_OFFSET
@@ -39,6 +39,17 @@
* c00e000000000000 << 3 + a80e000000000000 = c00fc00000000000
*/
#define KASAN_SHADOW_END 0xc00fc00000000000UL
+
+#else
+
+/*
+ * The shadow ends before the highest accessible address
+ * because we don't need a shadow for the shadow.
+ * But it doesn't hurt to have a shadow for the shadow,
+ * keep shadow end aligned eases things.
+ */
+#define KASAN_SHADOW_END 0xc000200000000000UL
+
#endif

#ifdef CONFIG_KASAN
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index d3eea633d11a..cf2c08902c05 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -965,6 +965,9 @@ start_here_multiplatform:
* and SLB setup before we turn on relocation.
*/

+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
/* Restore parameters passed from prom_init/kexec */
mr r3,r31
LOAD_REG_ADDR(r12, DOTSYM(early_setup))
diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index 4999aadb1867..699eeffd9f55 100644
--- a/arch/powerpc/mm/kasan/Makefile
+++ b/arch/powerpc/mm/kasan/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_PPC32) += init_32.o
obj-$(CONFIG_PPC_8xx) += 8xx.o
obj-$(CONFIG_PPC_BOOK3S_32) += book3s_32.o
obj-$(CONFIG_PPC_BOOK3S_64) += init_book3s_64.o
+obj-$(CONFIG_PPC_BOOK3E_64) += init_book3e_64.o
diff --git a/arch/powerpc/mm/kasan/init_book3e_64.c b/arch/powerpc/mm/kasan/init_book3e_64.c
new file mode 100644
index 000000000000..11519e88dc6b
--- /dev/null
+++ b/arch/powerpc/mm/kasan/init_book3e_64.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KASAN for 64-bit Book3e powerpc
+ *
+ * Copyright 2022, Christophe Leroy, CS GROUP France
+ */
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/printk.h>
+#include <linux/memblock.h>
+#include <linux/set_memory.h>
+
+#include <asm/pgalloc.h>
+
+static inline bool kasan_pud_table(p4d_t p4d)
+{
+ return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
+}
+
+static inline bool kasan_pmd_table(pud_t pud)
+{
+ return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
+}
+
+static inline bool kasan_pte_table(pmd_t pmd)
+{
+ return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
+}
+
+static int __init kasan_map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
+{
+ pgd_t *pgdp;
+ p4d_t *p4dp;
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ pgdp = pgd_offset_k(ea);
+ p4dp = p4d_offset(pgdp, ea);
+ if (kasan_pud_table(*p4dp)) {
+ pudp = memblock_alloc(PUD_TABLE_SIZE, PUD_TABLE_SIZE);
+ memcpy(pudp, kasan_early_shadow_pud, PUD_TABLE_SIZE);
+ p4d_populate(&init_mm, p4dp, pudp);
+ }
+ pudp = pud_offset(p4dp, ea);
+ if (kasan_pmd_table(*pudp)) {
+ pmdp = memblock_alloc(PMD_TABLE_SIZE, PMD_TABLE_SIZE);
+ memcpy(pmdp, kasan_early_shadow_pmd, PMD_TABLE_SIZE);
+ pud_populate(&init_mm, pudp, pmdp);
+ }
+ pmdp = pmd_offset(pudp, ea);
+ if (kasan_pte_table(*pmdp)) {
+ ptep = memblock_alloc(PTE_TABLE_SIZE, PTE_TABLE_SIZE);
+ memcpy(ptep, kasan_early_shadow_pte, PTE_TABLE_SIZE);
+ pmd_populate_kernel(&init_mm, pmdp, ptep);
+ }
+ ptep = pte_offset_kernel(pmdp, ea);
+
+ __set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot), 0);
+
+ return 0;
+}
+
+static void __init kasan_init_phys_region(void *start, void *end)
+{
+ unsigned long k_start, k_end, k_cur;
+ void *va;
+
+ if (start >= end)
+ return;
+
+ k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
+ k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
+
+ va = memblock_alloc(k_end - k_start, PAGE_SIZE);
+ for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
+ kasan_map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
+}
+
+void __init kasan_early_init(void)
+{
+ int i;
+ unsigned long addr;
+ pgd_t *pgd = pgd_offset_k(KASAN_SHADOW_START);
+ pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
+
+ BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
+ BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
+
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
+ &kasan_early_shadow_pte[i], zero_pte, 0);
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
+ kasan_early_shadow_pte);
+
+ for (i = 0; i < PTRS_PER_PUD; i++)
+ pud_populate(&init_mm, &kasan_early_shadow_pud[i],
+ kasan_early_shadow_pmd);
+
+ for (addr = KASAN_SHADOW_START; addr != KASAN_SHADOW_END; addr += PGDIR_SIZE)
+ p4d_populate(&init_mm, p4d_offset(pgd++, addr), kasan_early_shadow_pud);
+}
+
+void __init kasan_init(void)
+{
+ phys_addr_t start, end;
+ u64 i;
+ pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
+
+ for_each_mem_range(i, &start, &end)
+ kasan_init_phys_region((void *)start, (void *)end);
+
+ if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
+ kasan_remove_zero_shadow((void *)VMALLOC_START, VMALLOC_SIZE);
+
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
+ &kasan_early_shadow_pte[i], zero_pte, 0);
+
+ flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+ memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+
+ /* Enable error messages */
+ init_task.kasan_depth = 0;
+ pr_info("KASAN init done\n");
+}
+
+void __init kasan_late_init(void) { }
diff --git a/arch/powerpc/mm/kasan/init_book3s_64.c b/arch/powerpc/mm/kasan/init_book3s_64.c
index 0da5566d6b84..9300d641cf9a 100644
--- a/arch/powerpc/mm/kasan/init_book3s_64.c
+++ b/arch/powerpc/mm/kasan/init_book3s_64.c
@@ -99,4 +99,6 @@ void __init kasan_init(void)
pr_info("KASAN init done\n");
}

+void __init kasan_early_init(void) { }
+
void __init kasan_late_init(void) { }
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 9e2df4b66478..383ed4fe6013 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -2,7 +2,6 @@
config PPC32
bool
default y if !PPC64
- select KASAN_VMALLOC if KASAN && MODULES

config PPC64
bool "64-bit kernel"
--
2.36.1