[PATCH v3 01/13] riscv: Move KASAN mapping next to the kernel mapping
Alexandre Ghiti
alexandre.ghiti at canonical.com
Mon Dec 6 02:46:45 PST 2021
Now that KASAN_SHADOW_OFFSET is defined at compile time as a config,
this value must remain constant whatever the size of the virtual address
space, which is only possible by pushing this region at the end of the
address space next to the kernel mapping.
Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
---
Documentation/riscv/vm-layout.rst | 12 ++++++------
arch/riscv/Kconfig | 4 ++--
arch/riscv/include/asm/kasan.h | 4 ++--
arch/riscv/include/asm/page.h | 6 +++++-
arch/riscv/include/asm/pgtable.h | 6 ++++--
arch/riscv/mm/init.c | 25 +++++++++++++------------
6 files changed, 32 insertions(+), 25 deletions(-)
diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
index b7f98930d38d..1bd687b97104 100644
--- a/Documentation/riscv/vm-layout.rst
+++ b/Documentation/riscv/vm-layout.rst
@@ -47,12 +47,12 @@ RISC-V Linux Kernel SV39
| Kernel-space virtual memory, shared between all processes:
____________________________________________________________|___________________________________________________________
| | | |
- ffffffc000000000 | -256 GB | ffffffc7ffffffff | 32 GB | kasan
- ffffffcefee00000 | -196 GB | ffffffcefeffffff | 2 MB | fixmap
- ffffffceff000000 | -196 GB | ffffffceffffffff | 16 MB | PCI io
- ffffffcf00000000 | -196 GB | ffffffcfffffffff | 4 GB | vmemmap
- ffffffd000000000 | -192 GB | ffffffdfffffffff | 64 GB | vmalloc/ioremap space
- ffffffe000000000 | -128 GB | ffffffff7fffffff | 124 GB | direct mapping of all physical memory
+ ffffffc6fee00000 | -228 GB | ffffffc6feffffff | 2 MB | fixmap
+ ffffffc6ff000000 | -228 GB | ffffffc6ffffffff | 16 MB | PCI io
+ ffffffc700000000 | -228 GB | ffffffc7ffffffff | 4 GB | vmemmap
+ ffffffc800000000 | -224 GB | ffffffd7ffffffff | 64 GB | vmalloc/ioremap space
+ ffffffd800000000 | -160 GB | fffffff6ffffffff | 124 GB | direct mapping of all physical memory
+ fffffff700000000 | -36 GB | fffffffeffffffff | 32 GB | kasan
__________________|____________|__________________|_________|____________________________________________________________
|
|
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6d5b63bd4bd9..6cd98ade5ebc 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -161,12 +161,12 @@ config PAGE_OFFSET
default 0xC0000000 if 32BIT && MAXPHYSMEM_1GB
default 0x80000000 if 64BIT && !MMU
default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
- default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
+ default 0xffffffd800000000 if 64BIT && MAXPHYSMEM_128GB
config KASAN_SHADOW_OFFSET
hex
depends on KASAN_GENERIC
- default 0xdfffffc800000000 if 64BIT
+ default 0xdfffffff00000000 if 64BIT
default 0xffffffff if 32BIT
config ARCH_FLATMEM_ENABLE
diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h
index b00f503ec124..257a2495145a 100644
--- a/arch/riscv/include/asm/kasan.h
+++ b/arch/riscv/include/asm/kasan.h
@@ -28,8 +28,8 @@
#define KASAN_SHADOW_SCALE_SHIFT 3
#define KASAN_SHADOW_SIZE (UL(1) << ((CONFIG_VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
-#define KASAN_SHADOW_START KERN_VIRT_START
-#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
+#define KASAN_SHADOW_START (KASAN_SHADOW_END - KASAN_SHADOW_SIZE)
+#define KASAN_SHADOW_END MODULES_LOWEST_VADDR
#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
void kasan_init(void);
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 109c97e991a6..e03559f9b35e 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -33,7 +33,11 @@
*/
#define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
-#define KERN_VIRT_SIZE (-PAGE_OFFSET)
+/*
+ * Half of the kernel address space (half of the entries of the page global
+ * directory) is for the direct mapping.
+ */
+#define KERN_VIRT_SIZE ((PTRS_PER_PGD / 2 * PGDIR_SIZE) / 2)
#ifndef __ASSEMBLY__
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 39b550310ec6..d34f3a7a9701 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -39,8 +39,10 @@
/* Modules always live before the kernel */
#ifdef CONFIG_64BIT
-#define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
-#define MODULES_END (PFN_ALIGN((unsigned long)&_start))
+/* This is used to define the end of the KASAN shadow region */
+#define MODULES_LOWEST_VADDR (KERNEL_LINK_ADDR - SZ_2G)
+#define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
+#define MODULES_END (PFN_ALIGN((unsigned long)&_start))
#endif
/*
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c0cddf0fc22d..4224e9d0ecf5 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -103,6 +103,9 @@ static void __init print_vm_layout(void)
print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
(unsigned long)high_memory);
#ifdef CONFIG_64BIT
+#ifdef CONFIG_KASAN
+ print_mlm("kasan", KASAN_SHADOW_START, KASAN_SHADOW_END);
+#endif
print_mlm("kernel", (unsigned long)KERNEL_LINK_ADDR,
(unsigned long)ADDRESS_SPACE_END);
#endif
@@ -130,18 +133,8 @@ void __init mem_init(void)
print_vm_layout();
}
-/*
- * The default maximal physical memory size is -PAGE_OFFSET for 32-bit kernel,
- * whereas for 64-bit kernel, the end of the virtual address space is occupied
- * by the modules/BPF/kernel mappings which reduces the available size of the
- * linear mapping.
- * Limit the memory size via mem.
- */
-#ifdef CONFIG_64BIT
-static phys_addr_t memory_limit = -PAGE_OFFSET - SZ_4G;
-#else
-static phys_addr_t memory_limit = -PAGE_OFFSET;
-#endif
+/* Limit the memory size via mem. */
+static phys_addr_t memory_limit;
static int __init early_mem(char *p)
{
@@ -613,6 +606,14 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
riscv_pfn_base = PFN_DOWN(kernel_map.phys_addr);
+ /*
+ * The default maximal physical memory size is KERN_VIRT_SIZE for 32-bit
+ * kernel, whereas for 64-bit kernel, the end of the virtual address
+ * space is occupied by the modules/BPF/kernel mappings which reduces
+ * the available size of the linear mapping.
+ */
+ memory_limit = KERN_VIRT_SIZE - (IS_ENABLED(CONFIG_64BIT) ? SZ_4G : 0);
+
/* Sanity check alignment and size */
BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
BUG_ON((kernel_map.phys_addr % PMD_SIZE) != 0);
--
2.32.0
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