Commit-ID: 8f3e474f3cea7b2470218a6ed6da47ff02147dce Gitweb: http://git.kernel.org/tip/8f3e474f3cea7b2470218a6ed6da47ff02147dce Author: Dmitry Safonov <dsafo...@virtuozzo.com> AuthorDate: Mon, 6 Mar 2017 17:17:18 +0300 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Mon, 13 Mar 2017 14:59:22 +0100
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 <dsafo...@virtuozzo.com> Cc: 0x7f454...@gmail.com Cc: linux...@kvack.org Cc: Andy Lutomirski <l...@kernel.org> Cc: Cyrill Gorcunov <gorcu...@openvz.org> Cc: Borislav Petkov <b...@suse.de> Cc: "Kirill A. Shutemov" <kirill.shute...@linux.intel.com> Link: http://lkml.kernel.org/r/20170306141721.9188-3-dsafo...@virtuozzo.com Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- arch/x86/include/asm/elf.h | 24 ++++++++++--------- arch/x86/include/asm/processor.h | 4 +++- arch/x86/mm/mmap.c | 50 +++++++++++++++++++++++++--------------- 3 files changed, 48 insertions(+), 30 deletions(-) diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 9d49c18..b908141 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), diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f385eca..7caa2ac 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -797,6 +797,7 @@ 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 @@ -873,7 +874,8 @@ 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 f31ed70..1e9cb94 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -36,25 +36,23 @@ struct va_alignment __read_mostly 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 mmap_rnd_compat_bits # define mmap64_rnd_bits mmap_rnd_bits @@ -63,6 +61,8 @@ static unsigned long stack_maxrandom_size(void) # define mmap64_rnd_bits mmap_rnd_bits #endif +#define SIZE_128M (128 * 1024 * 1024UL) + static int mmap_is_legacy(void) { if (current->personality & ADDR_COMPAT_LAYOUT) @@ -84,16 +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); +} + +static unsigned long mmap_legacy_base(unsigned long rnd, + unsigned long task_size) +{ + return __TASK_UNMAPPED_BASE(task_size) + rnd; } /* @@ -107,13 +121,13 @@ void arch_pick_mmap_layout(struct mm_struct *mm) if (current->flags & PF_RANDOMIZE) random_factor = arch_mmap_rnd(); - mm->mmap_legacy_base = TASK_UNMAPPED_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; } 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; } }
