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>
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@ -293,8 +293,19 @@ do { \
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} \
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} while (0)
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/*
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* True on X86_32 or when emulating IA32 on X86_64
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*/
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static inline int mmap_is_ia32(void)
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{
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return IS_ENABLED(CONFIG_X86_32) ||
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(IS_ENABLED(CONFIG_COMPAT) &&
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test_thread_flag(TIF_ADDR32));
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}
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#ifdef CONFIG_X86_32
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#define __STACK_RND_MASK(is32bit) (0x7ff)
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#define STACK_RND_MASK (0x7ff)
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#define ARCH_DLINFO ARCH_DLINFO_IA32
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@ -304,7 +315,8 @@ do { \
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#else /* CONFIG_X86_32 */
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/* 1GB for 64bit, 8MB for 32bit */
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#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)
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#define __STACK_RND_MASK(is32bit) ((is32bit) ? 0x7ff : 0x3fffff)
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#define STACK_RND_MASK __STACK_RND_MASK(mmap_is_ia32())
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#define ARCH_DLINFO \
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do { \
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@ -348,16 +360,6 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
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int uses_interp);
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#define compat_arch_setup_additional_pages compat_arch_setup_additional_pages
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/*
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* True on X86_32 or when emulating IA32 on X86_64
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*/
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static inline int mmap_is_ia32(void)
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{
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return IS_ENABLED(CONFIG_X86_32) ||
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(IS_ENABLED(CONFIG_COMPAT) &&
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test_thread_flag(TIF_ADDR32));
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}
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/* Do not change the values. See get_align_mask() */
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enum align_flags {
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ALIGN_VA_32 = BIT(0),
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@ -797,6 +797,7 @@ static inline void spin_lock_prefetch(const void *x)
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/*
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* User space process size: 3GB (default).
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*/
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#define IA32_PAGE_OFFSET PAGE_OFFSET
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#define TASK_SIZE PAGE_OFFSET
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#define TASK_SIZE_MAX TASK_SIZE
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#define STACK_TOP TASK_SIZE
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@ -873,7 +874,8 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
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* This decides where the kernel will search for a free chunk of vm
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* space during mmap's.
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*/
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#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 3))
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#define __TASK_UNMAPPED_BASE(task_size) (PAGE_ALIGN(task_size / 3))
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#define TASK_UNMAPPED_BASE __TASK_UNMAPPED_BASE(TASK_SIZE)
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#define KSTK_EIP(task) (task_pt_regs(task)->ip)
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@ -36,25 +36,23 @@ struct va_alignment __read_mostly va_align = {
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.flags = -1,
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};
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static unsigned long stack_maxrandom_size(void)
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static inline unsigned long tasksize_32bit(void)
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{
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return IA32_PAGE_OFFSET;
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}
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static unsigned long stack_maxrandom_size(unsigned long task_size)
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{
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unsigned long max = 0;
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if ((current->flags & PF_RANDOMIZE) &&
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!(current->personality & ADDR_NO_RANDOMIZE)) {
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max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT;
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max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
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max <<= PAGE_SHIFT;
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}
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return max;
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}
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/*
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* Top of mmap area (just below the process stack).
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*
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* Leave an at least ~128 MB hole with possible stack randomization.
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*/
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#define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
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#define MAX_GAP (TASK_SIZE/6*5)
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#ifdef CONFIG_COMPAT
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# define mmap32_rnd_bits mmap_rnd_compat_bits
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# define mmap64_rnd_bits mmap_rnd_bits
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@ -63,6 +61,8 @@ static unsigned long stack_maxrandom_size(void)
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# define mmap64_rnd_bits mmap_rnd_bits
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#endif
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#define SIZE_128M (128 * 1024 * 1024UL)
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static int mmap_is_legacy(void)
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{
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if (current->personality & ADDR_COMPAT_LAYOUT)
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@ -84,16 +84,30 @@ unsigned long arch_mmap_rnd(void)
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return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
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}
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static unsigned long mmap_base(unsigned long rnd)
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static unsigned long mmap_base(unsigned long rnd, unsigned long task_size)
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{
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unsigned long gap = rlimit(RLIMIT_STACK);
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unsigned long gap_min, gap_max;
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if (gap < MIN_GAP)
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gap = MIN_GAP;
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else if (gap > MAX_GAP)
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gap = MAX_GAP;
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/*
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* Top of mmap area (just below the process stack).
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* Leave an at least ~128 MB hole with possible stack randomization.
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*/
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gap_min = SIZE_128M + stack_maxrandom_size(task_size);
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gap_max = (task_size / 6) * 5;
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return PAGE_ALIGN(TASK_SIZE - gap - rnd);
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if (gap < gap_min)
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gap = gap_min;
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else if (gap > gap_max)
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gap = gap_max;
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return PAGE_ALIGN(task_size - gap - rnd);
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}
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static unsigned long mmap_legacy_base(unsigned long rnd,
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unsigned long task_size)
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{
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return __TASK_UNMAPPED_BASE(task_size) + rnd;
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}
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/*
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@ -107,13 +121,13 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
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if (current->flags & PF_RANDOMIZE)
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random_factor = arch_mmap_rnd();
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mm->mmap_legacy_base = TASK_UNMAPPED_BASE + random_factor;
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mm->mmap_legacy_base = mmap_legacy_base(random_factor, TASK_SIZE);
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if (mmap_is_legacy()) {
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mm->mmap_base = mm->mmap_legacy_base;
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mm->get_unmapped_area = arch_get_unmapped_area;
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} else {
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mm->mmap_base = mmap_base(random_factor);
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mm->mmap_base = mmap_base(random_factor, TASK_SIZE);
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mm->get_unmapped_area = arch_get_unmapped_area_topdown;
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}
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}
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