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>

4 files changed, 44 insertions, 6 deletions

diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
index 395acb12b0d1..b4f14c6c09d9 100644
--- a/arch/x86/kernel/doublefault_32.c
+++ b/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),
         }
 };
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 7fb737c6b54f..8876220d906b 100644
--- a/arch/x86/mm/ioremap.c
+++ b/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 &&
-                                        is_vmalloc_addr((void *)x)));
+        VIRTUAL_BUG_ON(x < PAGE_OFFSET);
+        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)
diff --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index c91574776751..d4f1d5791fc1 100644
--- a/include/asm-x86/page.h
+++ b/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__ */
 
diff --git a/include/asm-x86/page_32.h b/include/asm-x86/page_32.h
index 9c5a737a9af9..5d6a68a1067a 100644
--- a/include/asm-x86/page_32.h
+++ b/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)