From b4abe38fd698ace6942edeeb79a5b8a60a7af4fa Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Fri, 26 Apr 2019 16:23:32 +0000
Subject: [PATCH] powerpc/32: prepare shadow area for KASAN
This patch prepares a shadow area for KASAN.
The shadow area will be at the top of the kernel virtual
memory space above the fixmap area and will occupy one
eighth of the total kernel virtual memory space.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/Kconfig.debug | 5 +++++
arch/powerpc/include/asm/fixmap.h | 5 +++++
arch/powerpc/include/asm/kasan.h | 16 ++++++++++++++++
arch/powerpc/mm/mem.c | 4 ++++
arch/powerpc/mm/ptdump/ptdump.c | 8 ++++++++
5 files changed, 38 insertions(+)
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 4e00cb0a54646..61febbbdd02b3 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -366,3 +366,8 @@ config PPC_FAST_ENDIAN_SWITCH
depends on DEBUG_KERNEL && PPC_BOOK3S_64
help
If you're unsure what this is, say N.
+
+config KASAN_SHADOW_OFFSET
+ hex
+ depends on KASAN
+ default 0xe0000000
diff --git a/arch/powerpc/include/asm/fixmap.h b/arch/powerpc/include/asm/fixmap.h
index b9fbed84ddca4..0cfc365d814ba 100644
--- a/arch/powerpc/include/asm/fixmap.h
+++ b/arch/powerpc/include/asm/fixmap.h
@@ -22,7 +22,12 @@
#include <asm/kmap_types.h>
#endif
+#ifdef CONFIG_KASAN
+#include <asm/kasan.h>
+#define FIXADDR_TOP (KASAN_SHADOW_START - PAGE_SIZE)
+#else
#define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE))
+#endif
/*
* Here we define all the compile-time 'special' virtual
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index 2c179a39d4ba5..05274dea31091 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -12,4 +12,20 @@
#define EXPORT_SYMBOL_KASAN(fn)
#endif
+#ifndef __ASSEMBLY__
+
+#include <asm/page.h>
+
+#define KASAN_SHADOW_SCALE_SHIFT 3
+
+#define KASAN_SHADOW_START (KASAN_SHADOW_OFFSET + \
+ (PAGE_OFFSET >> KASAN_SHADOW_SCALE_SHIFT))
+
+#define KASAN_SHADOW_OFFSET ASM_CONST(CONFIG_KASAN_SHADOW_OFFSET)
+
+#define KASAN_SHADOW_END 0UL
+
+#define KASAN_SHADOW_SIZE (KASAN_SHADOW_END - KASAN_SHADOW_START)
+
+#endif /* __ASSEMBLY */
#endif
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 105c58f8900aa..cd525d709072a 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -310,6 +310,10 @@ void __init mem_init(void)
mem_init_print_info(NULL);
#ifdef CONFIG_PPC32
pr_info("Kernel virtual memory layout:\n");
+#ifdef CONFIG_KASAN
+ pr_info(" * 0x%08lx..0x%08lx : kasan shadow mem\n",
+ KASAN_SHADOW_START, KASAN_SHADOW_END);
+#endif
pr_info(" * 0x%08lx..0x%08lx : fixmap\n", FIXADDR_START, FIXADDR_TOP);
#ifdef CONFIG_HIGHMEM
pr_info(" * 0x%08lx..0x%08lx : highmem PTEs\n",
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 63fc56feea15b..48135ba6fa74d 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -100,6 +100,10 @@ static struct addr_marker address_markers[] = {
#endif
{ 0, "Fixmap start" },
{ 0, "Fixmap end" },
+#endif
+#ifdef CONFIG_KASAN
+ { 0, "kasan shadow mem start" },
+ { 0, "kasan shadow mem end" },
#endif
{ -1, NULL },
};
@@ -323,6 +327,10 @@ static void populate_markers(void)
#endif
address_markers[i++].start_address = FIXADDR_START;
address_markers[i++].start_address = FIXADDR_TOP;
+#ifdef CONFIG_KASAN
+ address_markers[i++].start_address = KASAN_SHADOW_START;
+ address_markers[i++].start_address = KASAN_SHADOW_END;
+#endif
#endif /* CONFIG_PPC64 */
}