x86/mm: Add task_size parameter to mmap_base()

To correctly handle 32-bit and 64-bit mmap() syscalls in 64bit applications
its required to have separate address bases to place a mapping.

The tasksize can be used as an indicator to select the proper parameters
for mmap_base().

This requires the following changes:

 - Add task_size argument to mmap_base() and make the calculation based on it.
 - Provide mmap_legacy_base() as a seperate function
 - Use the new functions in arch_pick_mmap_layout()

[ tglx: Massaged changelog ]

Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: 0x7f454c46@gmail.com
Cc: linux-mm@kvack.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20170306141721.9188-3-dsafonov@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 13 insertions, 11 deletions

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 9d49c18b5ea9..b908141cf0c4 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -293,8 +293,19 @@ do {									\
 	}								\
 } while (0)
 
+/*
+ * True on X86_32 or when emulating IA32 on X86_64
+ */
+static inline int mmap_is_ia32(void)
+{
+	return IS_ENABLED(CONFIG_X86_32) ||
+	       (IS_ENABLED(CONFIG_COMPAT) &&
+		test_thread_flag(TIF_ADDR32));
+}
+
 #ifdef CONFIG_X86_32
 
+#define __STACK_RND_MASK(is32bit) (0x7ff)
 #define STACK_RND_MASK (0x7ff)
 
 #define ARCH_DLINFO		ARCH_DLINFO_IA32
@@ -304,7 +315,8 @@ do {									\
 #else /* CONFIG_X86_32 */
 
 /* 1GB for 64bit, 8MB for 32bit */
-#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)
+#define __STACK_RND_MASK(is32bit) ((is32bit) ? 0x7ff : 0x3fffff)
+#define STACK_RND_MASK __STACK_RND_MASK(mmap_is_ia32())
 
 #define ARCH_DLINFO							\
 do {									\
@@ -348,16 +360,6 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
 					      int uses_interp);
 #define compat_arch_setup_additional_pages compat_arch_setup_additional_pages
 
-/*
- * True on X86_32 or when emulating IA32 on X86_64
- */
-static inline int mmap_is_ia32(void)
-{
-	return IS_ENABLED(CONFIG_X86_32) ||
-	       (IS_ENABLED(CONFIG_COMPAT) &&
-		test_thread_flag(TIF_ADDR32));
-}
-
 /* Do not change the values. See get_align_mask() */
 enum align_flags {
 	ALIGN_VA_32	= BIT(0),