We have to do the allocation of bounds tables in kernel (See the patch "on-demand kernel allocation of bounds tables"). Moreover, if we want to track MPX VMAs we need to be able to stick new VM_MPX flag and a specific vm_ops for MPX in the vma_area_struct. But there are not suitable interfaces to do this in current kernel. Existing interfaces, like do_mmap_pgoff(), could not stick specific ->vm_ops in the vma_area_struct when a VMA is created. So, this patch adds MPX specific mmap interface to do the allocation of bounds tables. Signed-off-by: Qiaowei Ren <qiaowei.ren@xxxxxxxxx> --- arch/x86/Kconfig | 4 ++ arch/x86/include/asm/mpx.h | 38 +++++++++++++++++++++ arch/x86/mm/Makefile | 2 + arch/x86/mm/mpx.c | 79 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 123 insertions(+), 0 deletions(-) create mode 100644 arch/x86/include/asm/mpx.h create mode 100644 arch/x86/mm/mpx.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4b663e1..e5bcc70 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -243,6 +243,10 @@ 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..5725ac4 --- /dev/null +++ b/arch/x86/include/asm/mpx.h @@ -0,0 +1,38 @@ +#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 + +unsigned long mpx_mmap(unsigned long len); + +#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..e1b28e6 --- /dev/null +++ b/arch/x86/mm/mpx.c @@ -0,0 +1,79 @@ +#include <linux/kernel.h> +#include <linux/syscalls.h> +#include <asm/mpx.h> +#include <asm/mman.h> +#include <linux/sched/sysctl.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 + * related maps, including bounds table and bounds directory. + * + * here we can stick new vm_flag VM_MPX in the vma_area_struct + * when create a bounds table or bounds directory, in order to + * track MPX specific memory. + */ +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; +} -- 1.7.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>