[Devel] [PATCH 07/11] ms/x86/mm: Add task_size parameter to mmap_base()
Dmitry Safonov
dsafonov at virtuozzo.com
Thu May 18 11:39:46 PDT 2017
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 at virtuozzo.com>
Cc: 0x7f454c46 at gmail.com
Cc: linux-mm at kvack.org
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Cyrill Gorcunov <gorcunov at openvz.org>
Cc: Borislav Petkov <bp at suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com>
Link: http://lkml.kernel.org/r/20170306141721.9188-3-dsafonov@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
[ms commit 8f3e474f3cea]
Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
arch/x86/include/asm/elf.h | 29 ++++++++++-----------
arch/x86/include/asm/processor.h | 4 ++-
arch/x86/mm/mmap.c | 56 +++++++++++++++++++++-------------------
3 files changed, 45 insertions(+), 44 deletions(-)
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index e114fff00087..e7057133088d 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -277,8 +277,19 @@ 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 VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO))
@@ -292,7 +303,8 @@ do { \
#define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */
/* 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 { \
@@ -343,21 +355,6 @@ extern int do_map_compat_vdso(unsigned long addr);
extern unsigned long arch_randomize_brk(struct mm_struct *mm);
#define arch_randomize_brk arch_randomize_brk
-/*
- * True on X86_32 or when emulating IA32 on X86_64
- */
-static inline int mmap_is_ia32(void)
-{
-#ifdef CONFIG_X86_32
- return 1;
-#endif
-#ifdef CONFIG_IA32_EMULATION
- if (test_thread_flag(TIF_ADDR32))
- return 1;
-#endif
- return 0;
-}
-
/* Do not change the values. See get_align_mask() */
enum align_flags {
ALIGN_VA_32 = BIT(0),
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 0c4e3faf8ac3..47a1ac9e1c10 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -841,6 +841,7 @@ static inline void spin_lock_prefetch(const void *x)
/*
* User space process size: 3GB (default).
*/
+#define IA32_PAGE_OFFSET PAGE_OFFSET
#define TASK_SIZE PAGE_OFFSET
#define TASK_SIZE_MAX TASK_SIZE
#define STACK_TOP TASK_SIZE
@@ -949,7 +950,8 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
-#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 3))
+#define __TASK_UNMAPPED_BASE(task_size) (PAGE_ALIGN(task_size / 3))
+#define TASK_UNMAPPED_BASE __TASK_UNMAPPED_BASE(TASK_SIZE)
#define KSTK_EIP(task) (task_pt_regs(task)->ip)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 83a986ef7651..d0c222d64bb1 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -35,25 +35,23 @@ struct __read_mostly va_alignment va_align = {
.flags = -1,
};
-static unsigned long stack_maxrandom_size(void)
+static inline unsigned long tasksize_32bit(void)
+{
+ return IA32_PAGE_OFFSET;
+}
+
+static unsigned long stack_maxrandom_size(unsigned long task_size)
{
unsigned long max = 0;
if ((current->flags & PF_RANDOMIZE) &&
!(current->personality & ADDR_NO_RANDOMIZE)) {
- max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT;
+ max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
+ max <<= PAGE_SHIFT;
}
return max;
}
-/*
- * Top of mmap area (just below the process stack).
- *
- * Leave an at least ~128 MB hole with possible stack randomization.
- */
-#define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
-#define MAX_GAP (TASK_SIZE/6*5)
-
#ifdef CONFIG_COMPAT
# define mmap32_rnd_bits 8
# define mmap64_rnd_bits 28
@@ -62,6 +60,8 @@ static unsigned long stack_maxrandom_size(void)
# define mmap64_rnd_bits 28
#endif
+#define SIZE_128M (128 * 1024 * 1024UL)
+
static int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -84,28 +84,30 @@ unsigned long arch_mmap_rnd(void)
return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
}
-static unsigned long mmap_base(unsigned long rnd)
+static unsigned long mmap_base(unsigned long rnd, unsigned long task_size)
{
unsigned long gap = rlimit(RLIMIT_STACK);
+ unsigned long gap_min, gap_max;
+
+ /*
+ * Top of mmap area (just below the process stack).
+ * Leave an at least ~128 MB hole with possible stack randomization.
+ */
+ gap_min = SIZE_128M + stack_maxrandom_size(task_size);
+ gap_max = (task_size / 6) * 5;
- if (gap < MIN_GAP)
- gap = MIN_GAP;
- else if (gap > MAX_GAP)
- gap = MAX_GAP;
+ if (gap < gap_min)
+ gap = gap_min;
+ else if (gap > gap_max)
+ gap = gap_max;
- return PAGE_ALIGN(TASK_SIZE - gap - rnd);
+ return PAGE_ALIGN(task_size - gap - rnd);
}
-/*
- * Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64
- * does, but not when emulating X86_32
- */
-static unsigned long mmap_legacy_base(unsigned long rnd)
+static unsigned long mmap_legacy_base(unsigned long rnd,
+ unsigned long task_size)
{
- if (mmap_is_ia32())
- return TASK_UNMAPPED_BASE;
- else
- return TASK_UNMAPPED_BASE + rnd;
+ return __TASK_UNMAPPED_BASE(task_size) + rnd;
}
/*
@@ -119,14 +121,14 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
if (current->flags & PF_RANDOMIZE)
random_factor = arch_mmap_rnd();
- mm->mmap_legacy_base = mmap_legacy_base(random_factor);
+ mm->mmap_legacy_base = mmap_legacy_base(random_factor, TASK_SIZE);
if (mmap_is_legacy()) {
mm->mmap_base = mm->mmap_legacy_base;
mm->get_unmapped_area = arch_get_unmapped_area;
mm->unmap_area = arch_unmap_area;
} else {
- mm->mmap_base = mmap_base(random_factor);
+ mm->mmap_base = mmap_base(random_factor, TASK_SIZE);
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
mm->unmap_area = arch_unmap_area_topdown;
}
--
2.12.2
More information about the Devel
mailing list