Commit-ID: 57319d80e1d328e34cb24868a4f4405661485e30 Gitweb: http://git.kernel.org/tip/57319d80e1d328e34cb24868a4f4405661485e30 Author: Qiaowei Ren <qiaowei....@intel.com> AuthorDate: Fri, 14 Nov 2014 07:18:27 -0800 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Tue, 18 Nov 2014 00:58:53 +0100
x86, mpx: Add MPX-specific mmap interface We have chosen to perform the allocation of bounds tables in kernel (See the patch "on-demand kernel allocation of bounds tables") and to mark these VMAs with VM_MPX. However, there is currently no suitable interface to actually do this. Existing interfaces, like do_mmap_pgoff(), have no way to set a modified ->vm_ops or ->vm_flags and don't hold mmap_sem long enough to let a caller do it. This patch wraps mmap_region() and hold mmap_sem long enough to make the modifications to the VMA which we need. Also note the 32/64-bit #ifdef in the header. We actually need to do this at runtime eventually. But, for now, we don't support running 32-bit binaries on 64-bit kernels. Support for this will come in later patches. Signed-off-by: Qiaowei Ren <qiaowei....@intel.com> Signed-off-by: Dave Hansen <dave.han...@linux.intel.com> Cc: linux...@kvack.org Cc: linux-m...@linux-mips.org Cc: Dave Hansen <d...@sr71.net> Link: http://lkml.kernel.org/r/20141114151827.ce440...@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- arch/x86/Kconfig | 4 +++ arch/x86/include/asm/mpx.h | 36 +++++++++++++++++++ arch/x86/mm/Makefile | 2 ++ arch/x86/mm/mpx.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 128 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ded8a67..967dfe0 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -248,6 +248,10 @@ config HAVE_INTEL_TXT def_bool y depends on INTEL_IOMMU && ACPI +config X86_INTEL_MPX + def_bool y + depends on CPU_SUP_INTEL + config X86_32_SMP def_bool y depends on X86_32 && SMP diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h new file mode 100644 index 0000000..7d7c5f5 --- /dev/null +++ b/arch/x86/include/asm/mpx.h @@ -0,0 +1,36 @@ +#ifndef _ASM_X86_MPX_H +#define _ASM_X86_MPX_H + +#include <linux/types.h> +#include <asm/ptrace.h> + +#ifdef CONFIG_X86_64 + +/* upper 28 bits [47:20] of the virtual address in 64-bit used to + * index into bounds directory (BD). + */ +#define MPX_BD_ENTRY_OFFSET 28 +#define MPX_BD_ENTRY_SHIFT 3 +/* bits [19:3] of the virtual address in 64-bit used to index into + * bounds table (BT). + */ +#define MPX_BT_ENTRY_OFFSET 17 +#define MPX_BT_ENTRY_SHIFT 5 +#define MPX_IGN_BITS 3 + +#else + +#define MPX_BD_ENTRY_OFFSET 20 +#define MPX_BD_ENTRY_SHIFT 2 +#define MPX_BT_ENTRY_OFFSET 10 +#define MPX_BT_ENTRY_SHIFT 4 +#define MPX_IGN_BITS 2 + +#endif + +#define MPX_BD_SIZE_BYTES (1UL<<(MPX_BD_ENTRY_OFFSET+MPX_BD_ENTRY_SHIFT)) +#define MPX_BT_SIZE_BYTES (1UL<<(MPX_BT_ENTRY_OFFSET+MPX_BT_ENTRY_SHIFT)) + +#define MPX_BNDSTA_ERROR_CODE 0x3 + +#endif /* _ASM_X86_MPX_H */ diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index 6a19ad9..ecfdc46 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -30,3 +30,5 @@ obj-$(CONFIG_ACPI_NUMA) += srat.o obj-$(CONFIG_NUMA_EMU) += numa_emulation.o obj-$(CONFIG_MEMTEST) += memtest.o + +obj-$(CONFIG_X86_INTEL_MPX) += mpx.o diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c new file mode 100644 index 0000000..72d13b0 --- /dev/null +++ b/arch/x86/mm/mpx.c @@ -0,0 +1,86 @@ +/* + * mpx.c - Memory Protection eXtensions + * + * Copyright (c) 2014, Intel Corporation. + * Qiaowei Ren <qiaowei....@intel.com> + * Dave Hansen <dave.han...@intel.com> + */ +#include <linux/kernel.h> +#include <linux/syscalls.h> +#include <linux/sched/sysctl.h> + +#include <asm/mman.h> +#include <asm/mpx.h> + +static const char *mpx_mapping_name(struct vm_area_struct *vma) +{ + return "[mpx]"; +} + +static struct vm_operations_struct mpx_vma_ops = { + .name = mpx_mapping_name, +}; + +/* + * This is really a simplified "vm_mmap". it only handles MPX + * bounds tables (the bounds directory is user-allocated). + * + * Later on, we use the vma->vm_ops to uniquely identify these + * VMAs. + */ +static unsigned long mpx_mmap(unsigned long len) +{ + unsigned long ret; + unsigned long addr, pgoff; + struct mm_struct *mm = current->mm; + vm_flags_t vm_flags; + struct vm_area_struct *vma; + + /* Only bounds table and bounds directory can be allocated here */ + if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES) + return -EINVAL; + + down_write(&mm->mmap_sem); + + /* Too many mappings? */ + if (mm->map_count > sysctl_max_map_count) { + ret = -ENOMEM; + goto out; + } + + /* Obtain the address to map to. we verify (or select) it and ensure + * that it represents a valid section of the address space. + */ + addr = get_unmapped_area(NULL, 0, len, 0, MAP_ANONYMOUS | MAP_PRIVATE); + if (addr & ~PAGE_MASK) { + ret = addr; + goto out; + } + + vm_flags = VM_READ | VM_WRITE | VM_MPX | + mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; + + /* Set pgoff according to addr for anon_vma */ + pgoff = addr >> PAGE_SHIFT; + + ret = mmap_region(NULL, addr, len, vm_flags, pgoff); + if (IS_ERR_VALUE(ret)) + goto out; + + vma = find_vma(mm, ret); + if (!vma) { + ret = -ENOMEM; + goto out; + } + vma->vm_ops = &mpx_vma_ops; + + if (vm_flags & VM_LOCKED) { + up_write(&mm->mmap_sem); + mm_populate(ret, len); + return ret; + } + +out: + up_write(&mm->mmap_sem); + return ret; +} -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
