This patch adds the PR_MPX_INIT and PR_MPX_RELEASE prctl() commands on the x86 platform. These commands can be used to init and release MPX related resource.
A MMU notifier will be registered during PR_MPX_INIT command execution. So the bound tables can be automatically deallocated when one memory area is unmapped. Signed-off-by: Qiaowei Ren <qiaowei....@intel.com> --- arch/x86/Kconfig | 4 ++ arch/x86/include/asm/mpx.h | 9 ++++ arch/x86/include/asm/processor.h | 16 +++++++ arch/x86/kernel/mpx.c | 84 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/prctl.h | 6 +++ kernel/sys.c | 12 +++++ 6 files changed, 131 insertions(+), 0 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ee2fb9d..695101a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -233,6 +233,10 @@ config HAVE_INTEL_TXT def_bool y depends on INTEL_IOMMU && ACPI +config HAVE_INTEL_MPX + def_bool y + select MMU_NOTIFIER + 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 index d074153..9652e9e 100644 --- a/arch/x86/include/asm/mpx.h +++ b/arch/x86/include/asm/mpx.h @@ -30,6 +30,15 @@ #endif +typedef union { + struct { + unsigned long ignored:MPX_IGN_BITS; + unsigned long l2index:MPX_L2_BITS; + unsigned long l1index:MPX_L1_BITS; + }; + unsigned long addr; +} mpx_addr; + void do_mpx_bt_fault(struct xsave_struct *xsave_buf); #endif /* _ASM_X86_MPX_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 43be6f6..ea4e72d 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -963,6 +963,22 @@ extern void start_thread(struct pt_regs *regs, unsigned long new_ip, extern int get_tsc_mode(unsigned long adr); extern int set_tsc_mode(unsigned int val); +#ifdef CONFIG_HAVE_INTEL_MPX + +/* Init/release a process' MPX related resource */ +#define MPX_INIT(tsk) mpx_init((tsk)) +#define MPX_RELEASE(tsk) mpx_release((tsk)) + +extern int mpx_init(struct task_struct *tsk); +extern int mpx_release(struct task_struct *tsk); + +#else /* CONFIG_HAVE_INTEL_MPX */ + +#define MPX_INIT(tsk) (-EINVAL) +#define MPX_RELEASE(tsk) (-EINVAL) + +#endif /* CONFIG_HAVE_INTEL_MPX */ + extern u16 amd_get_nb_id(int cpu); static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) diff --git a/arch/x86/kernel/mpx.c b/arch/x86/kernel/mpx.c index 767b3bf..ffe5aee 100644 --- a/arch/x86/kernel/mpx.c +++ b/arch/x86/kernel/mpx.c @@ -1,5 +1,7 @@ #include <linux/kernel.h> #include <linux/syscalls.h> +#include <linux/prctl.h> +#include <linux/mmu_notifier.h> #include <asm/processor.h> #include <asm/mpx.h> #include <asm/mman.h> @@ -7,6 +9,88 @@ #include <asm/fpu-internal.h> #include <asm/alternative.h> +static struct mmu_notifier mpx_mn; + +static void mpx_invl_range_end(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, unsigned long end) +{ + struct xsave_struct *xsave_buf; + unsigned long bt_size = 1UL << (MPX_L2_BITS+MPX_L2_SHIFT); + unsigned long bt_addr; + unsigned long bd_base; + unsigned long bd_entry, bde_start, bde_end; + mpx_addr lap; + + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + /* ignore swap notifications */ + pgd = pgd_offset(mm, start); + pud = pud_offset(pgd, start); + pmd = pmd_offset(pud, start); + pte = pte_offset_kernel(pmd, start); + if (!pte_present(*pte) && !pte_none(*pte) && !pte_file(*pte)) + return; + + /* get bound directory base address */ + fpu_xsave(¤t->thread.fpu); + xsave_buf = &(current->thread.fpu.state->xsave); + bd_base = xsave_buf->bndcsr.cfg_reg_u & MPX_BNDCFG_ADDR_MASK; + + /* get related bde range */ + lap.addr = start; + bde_start = bd_base + (lap.l1index << MPX_L1_SHIFT); + + lap.addr = end; + if (lap.ignored || lap.l2index) + bde_end = bd_base + (lap.l1index<<MPX_L1_SHIFT) + sizeof(long); + else + bde_end = bd_base + (lap.l1index<<MPX_L1_SHIFT); + + for (bd_entry = bde_start; bd_entry < bde_end; + bd_entry += sizeof(unsigned long)) { + + if (get_user(bt_addr, (long __user *)bd_entry)) + return; + + if (bt_addr & 0x1) { + user_atomic_cmpxchg_inatomic(&bt_addr, + (long __user *)bd_entry, bt_addr, 0); + do_munmap(mm, bt_addr & MPX_L2_NODE_ADDR_MASK, bt_size); + } + } +} + +static struct mmu_notifier_ops mpx_mmuops = { + .invalidate_range_end = mpx_invl_range_end, +}; + +int mpx_init(struct task_struct *tsk) +{ + if (!boot_cpu_has(X86_FEATURE_MPX)) + return -EINVAL; + + /* register mmu_notifier to delallocate the bound tables */ + mpx_mn.ops = &mpx_mmuops; + mmu_notifier_register(&mpx_mn, current->mm); + + return 0; +} + +int mpx_release(struct task_struct *tsk) +{ + if (!boot_cpu_has(X86_FEATURE_MPX)) + return -EINVAL; + + /* unregister mmu_notifier */ + mmu_notifier_unregister(&mpx_mn, current->mm); + + return 0; +} + static bool allocate_bt(unsigned long bd_entry) { unsigned long bt_size = 1UL << (MPX_L2_BITS+MPX_L2_SHIFT); diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 289760f..19ab881 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -149,4 +149,10 @@ #define PR_GET_TID_ADDRESS 40 +/* + * Init/release MPX related resource. + */ +#define PR_MPX_INIT 41 +#define PR_MPX_RELEASE 42 + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index c18ecca..bbaf573 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -92,6 +92,12 @@ #ifndef SET_TSC_CTL # define SET_TSC_CTL(a) (-EINVAL) #endif +#ifndef MPX_INIT +# define MPX_INIT(a) (-EINVAL) +#endif +#ifndef MPX_RELEASE +# define MPX_RELEASE(a) (-EINVAL) +#endif /* * this is where the system-wide overflow UID and GID are defined, for @@ -1999,6 +2005,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, if (arg2 || arg3 || arg4 || arg5) return -EINVAL; return current->no_new_privs ? 1 : 0; + case PR_MPX_INIT: + error = MPX_INIT(me); + break; + case PR_MPX_RELEASE: + error = MPX_RELEASE(me); + break; default: error = -EINVAL; break; -- 1.7.1 -- 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/