arm64: Add support for CONFIG_DEBUG_VIRTUAL

x86 has an option CONFIG_DEBUG_VIRTUAL to do additional checks
on virt_to_phys calls. The goal is to catch users who are calling
virt_to_phys on non-linear addresses immediately. This inclues callers
using virt_to_phys on image addresses instead of __pa_symbol. As features
such as CONFIG_VMAP_STACK get enabled for arm64, this becomes increasingly
important. Add checks to catch bad virt_to_phys usage.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index e703fb9defad..9b0ba191e48e 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -6,6 +6,8 @@ obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 obj-$(CONFIG_ARM64_PTDUMP_CORE)	+= dump.o
 obj-$(CONFIG_ARM64_PTDUMP_DEBUGFS)	+= ptdump_debugfs.o
 obj-$(CONFIG_NUMA)		+= numa.o
+obj-$(CONFIG_DEBUG_VIRTUAL)	+= physaddr.o
+KASAN_SANITIZE_physaddr.o	+= n
 
 obj-$(CONFIG_KASAN)		+= kasan_init.o
 KASAN_SANITIZE_kasan_init.o	:= n
diff --git a/arch/arm64/mm/physaddr.c b/arch/arm64/mm/physaddr.c
new file mode 100644
index 000000000000..91371daf397c
--- /dev/null
+++ b/arch/arm64/mm/physaddr.c
@@ -0,0 +1,30 @@
+#include <linux/bug.h>
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/mmdebug.h>
+#include <linux/mm.h>
+
+#include <asm/memory.h>
+
+phys_addr_t __virt_to_phys(unsigned long x)
+{
+	WARN(!__is_lm_address(x),
+	     "virt_to_phys used for non-linear address: %pK (%pS)\n",
+	      (void *)x,
+	      (void *)x);
+
+	return __virt_to_phys_nodebug(x);
+}
+EXPORT_SYMBOL(__virt_to_phys);
+
+phys_addr_t __phys_addr_symbol(unsigned long x)
+{
+	/*
+	 * This is bounds checking against the kernel image only.
+	 * __pa_symbol should only be used on kernel symbol addresses.
+	 */
+	VIRTUAL_BUG_ON(x < (unsigned long) KERNEL_START ||
+		       x > (unsigned long) KERNEL_END);
+	return __pa_symbol_nodebug(x);
+}
+EXPORT_SYMBOL(__phys_addr_symbol);