Commit-ID: 44b04912fa72489d403738f39e1c782614b7ae7c Gitweb: http://git.kernel.org/tip/44b04912fa72489d403738f39e1c782614b7ae7c Author: Kirill A. Shutemov <kirill.shute...@linux.intel.com> AuthorDate: Mon, 17 Jul 2017 01:59:51 +0300 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 21 Jul 2017 10:05:18 +0200
x86/mpx: Do not allow MPX if we have mappings above 47-bit MPX (without MAWA extension) cannot handle addresses above 47 bits, so we need to make sure that MPX cannot be enabled if we already have a VMA above the boundary and forbid creating such VMAs once MPX is enabled. The patch implements mpx_unmapped_area_check() which is called from all variants of get_unmapped_area() to check if the requested address fits mpx. On enabling MPX, we check if we already have any vma above 47-bit boundary and forbit the enabling if we do. As long as DEFAULT_MAP_WINDOW is equal to TASK_SIZE_MAX, the change is nop. It will change when we allow userspace to have mappings above 47-bits. Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Dave Hansen <dave.han...@intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-a...@vger.kernel.org Cc: linux...@kvack.org Link: http://lkml.kernel.org/r/20170716225954.74185-6-kirill.shute...@linux.intel.com [ Readability edits. ] Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/include/asm/mpx.h | 9 +++++++++ arch/x86/include/asm/processor.h | 3 +++ arch/x86/kernel/sys_x86_64.c | 9 +++++++++ arch/x86/mm/hugetlbpage.c | 6 ++++++ arch/x86/mm/mpx.c | 33 ++++++++++++++++++++++++++++++++- 5 files changed, 59 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h index a0d662b..7d74047 100644 --- a/arch/x86/include/asm/mpx.h +++ b/arch/x86/include/asm/mpx.h @@ -73,6 +73,9 @@ static inline void mpx_mm_init(struct mm_struct *mm) } void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long start, unsigned long end); + +unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len, + unsigned long flags); #else static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs) { @@ -94,6 +97,12 @@ static inline void mpx_notify_unmap(struct mm_struct *mm, unsigned long start, unsigned long end) { } + +static inline unsigned long mpx_unmapped_area_check(unsigned long addr, + unsigned long len, unsigned long flags) +{ + return addr; +} #endif /* CONFIG_X86_INTEL_MPX */ #endif /* _ASM_X86_MPX_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 973709d..c8d59fc 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -809,6 +809,7 @@ static inline void spin_lock_prefetch(const void *x) #define IA32_PAGE_OFFSET PAGE_OFFSET #define TASK_SIZE PAGE_OFFSET #define TASK_SIZE_MAX TASK_SIZE +#define DEFAULT_MAP_WINDOW TASK_SIZE #define STACK_TOP TASK_SIZE #define STACK_TOP_MAX STACK_TOP @@ -850,6 +851,8 @@ static inline void spin_lock_prefetch(const void *x) */ #define TASK_SIZE_MAX ((1UL << 47) - PAGE_SIZE) +#define DEFAULT_MAP_WINDOW TASK_SIZE_MAX + /* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c index 89bd0d6..f840e89 100644 --- a/arch/x86/kernel/sys_x86_64.c +++ b/arch/x86/kernel/sys_x86_64.c @@ -21,6 +21,7 @@ #include <asm/compat.h> #include <asm/ia32.h> #include <asm/syscalls.h> +#include <asm/mpx.h> /* * Align a virtual address to avoid aliasing in the I$ on AMD F15h. @@ -132,6 +133,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, struct vm_unmapped_area_info info; unsigned long begin, end; + addr = mpx_unmapped_area_check(addr, len, flags); + if (IS_ERR_VALUE(addr)) + return addr; + if (flags & MAP_FIXED) return addr; @@ -171,6 +176,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, unsigned long addr = addr0; struct vm_unmapped_area_info info; + addr = mpx_unmapped_area_check(addr, len, flags); + if (IS_ERR_VALUE(addr)) + return addr; + /* requested length too big for entire address space */ if (len > TASK_SIZE) return -ENOMEM; diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 868f02c..3cf89ad 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -18,6 +18,7 @@ #include <asm/tlbflush.h> #include <asm/pgalloc.h> #include <asm/elf.h> +#include <asm/mpx.h> #if 0 /* This is just for testing */ struct page * @@ -135,6 +136,11 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, if (len & ~huge_page_mask(h)) return -EINVAL; + + addr = mpx_unmapped_area_check(addr, len, flags); + if (IS_ERR_VALUE(addr)) + return addr; + if (len > TASK_SIZE) return -ENOMEM; diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 1c34b76..9ceaa95 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -355,10 +355,19 @@ int mpx_enable_management(void) */ bd_base = mpx_get_bounds_dir(); down_write(&mm->mmap_sem); + + /* MPX doesn't support addresses above 47 bits yet. */ + if (find_vma(mm, DEFAULT_MAP_WINDOW)) { + pr_warn_once("%s (%d): MPX cannot handle addresses " + "above 47-bits. Disabling.", + current->comm, current->pid); + ret = -ENXIO; + goto out; + } mm->context.bd_addr = bd_base; if (mm->context.bd_addr == MPX_INVALID_BOUNDS_DIR) ret = -ENXIO; - +out: up_write(&mm->mmap_sem); return ret; } @@ -1030,3 +1039,25 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma, if (ret) force_sig(SIGSEGV, current); } + +/* MPX cannot handle addresses above 47 bits yet. */ +unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len, + unsigned long flags) +{ + if (!kernel_managing_mpx_tables(current->mm)) + return addr; + if (addr + len <= DEFAULT_MAP_WINDOW) + return addr; + if (flags & MAP_FIXED) + return -ENOMEM; + + /* + * Requested len is larger than the whole area we're allowed to map in. + * Resetting hinting address wouldn't do much good -- fail early. + */ + if (len > DEFAULT_MAP_WINDOW) + return -ENOMEM; + + /* Look for unmap area within DEFAULT_MAP_WINDOW */ + return 0; +}
