x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y, v2

virt_addr_valid() calls __pa(), which calls __phys_addr(). With
CONFIG_DEBUG_VIRTUAL=y, __phys_addr() will kill the kernel if the
address *isn't* valid. That's clearly wrong for virt_addr_valid().

We also incorporate the debugging checks into virt_addr_valid().

Signed-off-by: Vegard Nossum <vegardno@ben.ifi.uio.no>
Acked-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/doublefault_32.c

@@ -66,6 +66,6 @@ struct tss_struct doublefault_tss __cacheline_aligned = {
 		.ds		= __USER_DS,
 		.fs		= __KERNEL_PERCPU,
 
-		.__cr3		= __phys_addr_const((unsigned long)swapper_pg_dir)
+		.__cr3		= __pa_nodebug(swapper_pg_dir),
 	}
 };

arch/x86/mm/ioremap.c

@@ -45,6 +45,27 @@ unsigned long __phys_addr(unsigned long x)
 }
 EXPORT_SYMBOL(__phys_addr);
 
+bool __virt_addr_valid(unsigned long x)
+{
+	if (x >= __START_KERNEL_map) {
+		x -= __START_KERNEL_map;
+		if (x >= KERNEL_IMAGE_SIZE)
+			return false;
+		x += phys_base;
+	} else {
+		if (x < PAGE_OFFSET)
+			return false;
+		x -= PAGE_OFFSET;
+		if (system_state == SYSTEM_BOOTING ?
+				x > MAXMEM : !phys_addr_valid(x)) {
+			return false;
+		}
+	}
+
+	return pfn_valid(x >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(__virt_addr_valid);
+
 #else
 
 static inline int phys_addr_valid(unsigned long addr)
@@ -56,13 +77,24 @@ static inline int phys_addr_valid(unsigned long addr)
 unsigned long __phys_addr(unsigned long x)
 {
 	/* VMALLOC_* aren't constants; not available at the boot time */
-	VIRTUAL_BUG_ON(x < PAGE_OFFSET || (system_state != SYSTEM_BOOTING &&
+	VIRTUAL_BUG_ON(x < PAGE_OFFSET);
-					is_vmalloc_addr((void *)x)));
+	VIRTUAL_BUG_ON(system_state != SYSTEM_BOOTING &&
+		is_vmalloc_addr((void *) x));
 	return x - PAGE_OFFSET;
 }
 EXPORT_SYMBOL(__phys_addr);
 #endif
 
+bool __virt_addr_valid(unsigned long x)
+{
+	if (x < PAGE_OFFSET)
+		return false;
+	if (system_state != SYSTEM_BOOTING && is_vmalloc_addr((void *) x))
+		return false;
+	return pfn_valid((x - PAGE_OFFSET) >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(__virt_addr_valid);
+
 #endif
 
 int page_is_ram(unsigned long pagenr)

include/asm-x86/page.h

@@ -179,6 +179,7 @@ static inline pteval_t native_pte_flags(pte_t pte)
 #endif	/* CONFIG_PARAVIRT */
 
 #define __pa(x)		__phys_addr((unsigned long)(x))
+#define __pa_nodebug(x)	__phys_addr_nodebug((unsigned long)(x))
 /* __pa_symbol should be used for C visible symbols.
    This seems to be the official gcc blessed way to do such arithmetic. */
 #define __pa_symbol(x)	__pa(__phys_reloc_hide((unsigned long)(x)))
@@ -188,9 +189,14 @@ static inline pteval_t native_pte_flags(pte_t pte)
 #define __boot_va(x)		__va(x)
 #define __boot_pa(x)		__pa(x)
 
+/*
+ * virt_to_page(kaddr) returns a valid pointer if and only if
+ * virt_addr_valid(kaddr) returns true.
+ */
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)
-#define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
+extern bool __virt_addr_valid(unsigned long kaddr);
+#define virt_addr_valid(kaddr)	__virt_addr_valid((unsigned long) (kaddr))
 
 #endif	/* __ASSEMBLY__ */
 

include/asm-x86/page_32.h

@@ -73,11 +73,11 @@ typedef struct page *pgtable_t;
 #endif
 
 #ifndef __ASSEMBLY__
-#define __phys_addr_const(x)	((x) - PAGE_OFFSET)
+#define __phys_addr_nodebug(x)	((x) - PAGE_OFFSET)
 #ifdef CONFIG_DEBUG_VIRTUAL
 extern unsigned long __phys_addr(unsigned long);
 #else
-#define __phys_addr(x)		((x) - PAGE_OFFSET)
+#define __phys_addr(x)		__phys_addr_nodebug(x)
 #endif
 #define __phys_reloc_hide(x)	RELOC_HIDE((x), 0)