ARM: Add KASan support

This adds KASan support to the ARM architecture. What we are doing is:

* Add __no_sanitize_address attribute to various lowlevel functions
  which do not run in a proper C environment
* Add non-instrumented variants of memset/memcpy (prefixed with '__')
* make original memcpy/memset weak symbols so strong definitions in
  lib/kasan/common.c can replace them
* Use non-instrumented memcpy in early functions
* call kasan_init()

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

4 files changed, 11 insertions, 6 deletions

diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile
index f7f9c30415..e7a6e3e6fb 100644
--- a/arch/arm/cpu/Makefile
+++ b/arch/arm/cpu/Makefile
@@ -9,6 +9,7 @@ AFLAGS_hyp.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
 AFLAGS_hyp.pbl.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
 
 obj-y += start.o entry.o entry_ll$(S64).o
+KASAN_SANITIZE_start.o := n
 
 pbl-$(CONFIG_BOARD_ARM_GENERIC_DT) += board-dt-2nd.o
 pbl-$(CONFIG_BOARD_ARM_GENERIC_DT_AARCH64) += board-dt-2nd-aarch64.o
@@ -51,3 +52,4 @@ pbl-y += entry.o entry_ll$(S64).o
 pbl-y += uncompress.o
 
 obj-pbl-y += common.o sections.o
+KASAN_SANITIZE_common.o := n
diff --git a/arch/arm/cpu/common.c b/arch/arm/cpu/common.c
index 33f148fc0e..8cfcc8f6ce 100644
--- a/arch/arm/cpu/common.c
+++ b/arch/arm/cpu/common.c
@@ -120,7 +120,7 @@ void relocate_to_current_adr(void)
 		dstart += sizeof(*rel);
 	}
 
-	memset(dynsym, 0, (unsigned long)dynend - (unsigned long)dynsym);
+	__memset(dynsym, 0, (unsigned long)dynend - (unsigned long)dynsym);
 #else
 #error "Architecture not specified"
 #endif
diff --git a/arch/arm/cpu/setupc.S b/arch/arm/cpu/setupc.S
index 8ae7c89a2c..55aa105b21 100644
--- a/arch/arm/cpu/setupc.S
+++ b/arch/arm/cpu/setupc.S
@@ -21,12 +21,12 @@ ENTRY(setup_c)
 	ldr	r2,=__bss_start
 	sub	r2, r2, r0
 	add	r1, r0, r4
-	bl	memcpy			/* memcpy(_text, _text + offset, __bss_start - _text) */
+	bl	__memcpy			/* memcpy(_text, _text + offset, __bss_start - _text) */
 1:	ldr	r0, =__bss_start
 	mov	r1, #0
 	ldr	r2, =__bss_stop
 	sub	r2, r2, r0
-	bl	memset			/* clear bss */
+	bl	__memset			/* clear bss */
 	bl	sync_caches_for_execution
 	sub	lr, r5, r4		/* adjust return address to new location */
 	pop	{r4, r5}
@@ -67,7 +67,7 @@ ENTRY(relocate_to_adr)
 	sub	r7, r7, r1		/* sub address where we are actually running */
 	add	r7, r7, r0		/* add address where we are going to run */
 
-	bl	memcpy			/* copy binary */
+	bl	__memcpy			/* copy binary */
 
 	bl	sync_caches_for_execution
 
diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index aeca459cb1..f48f5beea8 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -15,6 +15,7 @@
 #include <asm/unaligned.h>
 #include <asm/cache.h>
 #include <asm/mmu.h>
+#include <linux/kasan.h>
 #include <memory.h>
 #include <uncompress.h>
 #include <malloc.h>
@@ -135,7 +136,7 @@ static int barebox_memory_areas_init(void)
 }
 device_initcall(barebox_memory_areas_init);
 
-__noreturn void barebox_non_pbl_start(unsigned long membase,
+__noreturn __no_sanitize_address void barebox_non_pbl_start(unsigned long membase,
 		unsigned long memsize, void *boarddata)
 {
 	unsigned long endmem = membase + memsize;
@@ -233,6 +234,8 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
 	pr_debug("initializing malloc pool at 0x%08lx (size 0x%08lx)\n",
 			malloc_start, malloc_end - malloc_start);
 
+	kasan_init(membase, memsize, malloc_start - (memsize >> KASAN_SHADOW_SCALE_SHIFT));
+
 	mem_malloc_init((void *)malloc_start, (void *)malloc_end - 1);
 
 	if (IS_ENABLED(CONFIG_BOOTM_OPTEE))
@@ -259,7 +262,7 @@ void start(unsigned long membase, unsigned long memsize, void *boarddata);
  * First function in the uncompressed image. We get here from
  * the pbl. The stack already has been set up by the pbl.
  */
-void NAKED __section(.text_entry) start(unsigned long membase,
+void NAKED __no_sanitize_address __section(.text_entry) start(unsigned long membase,
 		unsigned long memsize, void *boarddata)
 {
 	barebox_non_pbl_start(membase, memsize, boarddata);