diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/bugs.h | 6 | ||||
| -rw-r--r-- | arch/x86/include/asm/disabled-features.h | 8 | ||||
| -rw-r--r-- | arch/x86/include/asm/mmu.h | 4 | ||||
| -rw-r--r-- | arch/x86/include/asm/mmu_context.h | 20 | ||||
| -rw-r--r-- | arch/x86/include/asm/mpx.h | 116 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 18 | ||||
| -rw-r--r-- | arch/x86/include/asm/trace/mpx.h | 134 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 36 | ||||
| -rw-r--r-- | arch/x86/kernel/setup.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/sys_x86_64.c | 9 | ||||
| -rw-r--r-- | arch/x86/mm/hugetlbpage.c | 5 | ||||
| -rw-r--r-- | arch/x86/mm/mmap.c | 2 | ||||
| -rw-r--r-- | arch/x86/mm/mpx.c | 938 |
14 files changed, 1 insertions, 1315 deletions
diff --git a/arch/x86/include/asm/bugs.h b/arch/x86/include/asm/bugs.h index 794eb2129bc6..92ae28389940 100644 --- a/arch/x86/include/asm/bugs.h +++ b/arch/x86/include/asm/bugs.h @@ -6,12 +6,6 @@ extern void check_bugs(void); -#if defined(CONFIG_CPU_SUP_INTEL) -void check_mpx_erratum(struct cpuinfo_x86 *c); -#else -static inline void check_mpx_erratum(struct cpuinfo_x86 *c) {} -#endif - #if defined(CONFIG_CPU_SUP_INTEL) && defined(CONFIG_X86_32) int ppro_with_ram_bug(void); #else diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h index a5ea841cc6d2..41d069fa8f2f 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -10,12 +10,6 @@ * cpu_feature_enabled(). */ -#ifdef CONFIG_X86_INTEL_MPX -# define DISABLE_MPX 0 -#else -# define DISABLE_MPX (1<<(X86_FEATURE_MPX & 31)) -#endif - #ifdef CONFIG_X86_SMAP # define DISABLE_SMAP 0 #else @@ -74,7 +68,7 @@ #define DISABLED_MASK6 0 #define DISABLED_MASK7 (DISABLE_PTI) #define DISABLED_MASK8 0 -#define DISABLED_MASK9 (DISABLE_MPX|DISABLE_SMAP) +#define DISABLED_MASK9 (DISABLE_SMAP) #define DISABLED_MASK10 0 #define DISABLED_MASK11 0 #define DISABLED_MASK12 0 diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index e78c7db87801..bdeae9291e5c 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -50,10 +50,6 @@ typedef struct { u16 pkey_allocation_map; s16 execute_only_pkey; #endif -#ifdef CONFIG_X86_INTEL_MPX - /* address of the bounds directory */ - void __user *bd_addr; -#endif } mm_context_t; #define INIT_MM_CONTEXT(mm) \ diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index b7135e92e571..a3e1c72a3ab9 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -12,7 +12,6 @@ #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include <asm/paravirt.h> -#include <asm/mpx.h> #include <asm/debugreg.h> extern atomic64_t last_mm_ctx_id; @@ -275,25 +274,6 @@ static inline bool is_64bit_mm(struct mm_struct *mm) static inline void arch_unmap(struct mm_struct *mm, unsigned long start, unsigned long end) { - /* - * mpx_notify_unmap() goes and reads a rarely-hot - * cacheline in the mm_struct. That can be expensive - * enough to be seen in profiles. - * - * The mpx_notify_unmap() call and its contents have been - * observed to affect munmap() performance on hardware - * where MPX is not present. - * - * The unlikely() optimizes for the fast case: no MPX - * in the CPU, or no MPX use in the process. Even if - * we get this wrong (in the unlikely event that MPX - * is widely enabled on some system) the overhead of - * MPX itself (reading bounds tables) is expected to - * overwhelm the overhead of getting this unlikely() - * consistently wrong. - */ - if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX))) - mpx_notify_unmap(mm, start, end); } /* diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h deleted file mode 100644 index 143a5c193ed3..000000000000 --- a/arch/x86/include/asm/mpx.h +++ /dev/null @@ -1,116 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _ASM_X86_MPX_H -#define _ASM_X86_MPX_H - -#include <linux/types.h> -#include <linux/mm_types.h> - -#include <asm/ptrace.h> -#include <asm/insn.h> - -/* - * NULL is theoretically a valid place to put the bounds - * directory, so point this at an invalid address. - */ -#define MPX_INVALID_BOUNDS_DIR ((void __user *)-1) -#define MPX_BNDCFG_ENABLE_FLAG 0x1 -#define MPX_BD_ENTRY_VALID_FLAG 0x1 - -/* - * The upper 28 bits [47:20] of the virtual address in 64-bit - * are used to index into bounds directory (BD). - * - * The directory is 2G (2^31) in size, and with 8-byte entries - * it has 2^28 entries. - */ -#define MPX_BD_SIZE_BYTES_64 (1UL<<31) -#define MPX_BD_ENTRY_BYTES_64 8 -#define MPX_BD_NR_ENTRIES_64 (MPX_BD_SIZE_BYTES_64/MPX_BD_ENTRY_BYTES_64) - -/* - * The 32-bit directory is 4MB (2^22) in size, and with 4-byte - * entries it has 2^20 entries. - */ -#define MPX_BD_SIZE_BYTES_32 (1UL<<22) -#define MPX_BD_ENTRY_BYTES_32 4 -#define MPX_BD_NR_ENTRIES_32 (MPX_BD_SIZE_BYTES_32/MPX_BD_ENTRY_BYTES_32) - -/* - * A 64-bit table is 4MB total in size, and an entry is - * 4 64-bit pointers in size. - */ -#define MPX_BT_SIZE_BYTES_64 (1UL<<22) -#define MPX_BT_ENTRY_BYTES_64 32 -#define MPX_BT_NR_ENTRIES_64 (MPX_BT_SIZE_BYTES_64/MPX_BT_ENTRY_BYTES_64) - -/* - * A 32-bit table is 16kB total in size, and an entry is - * 4 32-bit pointers in size. - */ -#define MPX_BT_SIZE_BYTES_32 (1UL<<14) -#define MPX_BT_ENTRY_BYTES_32 16 -#define MPX_BT_NR_ENTRIES_32 (MPX_BT_SIZE_BYTES_32/MPX_BT_ENTRY_BYTES_32) - -#define MPX_BNDSTA_TAIL 2 -#define MPX_BNDCFG_TAIL 12 -#define MPX_BNDSTA_ADDR_MASK (~((1UL<<MPX_BNDSTA_TAIL)-1)) -#define MPX_BNDCFG_ADDR_MASK (~((1UL<<MPX_BNDCFG_TAIL)-1)) -#define MPX_BNDSTA_ERROR_CODE 0x3 - -struct mpx_fault_info { - void __user *addr; - void __user *lower; - void __user *upper; -}; - -#ifdef CONFIG_X86_INTEL_MPX - -extern int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs); -extern int mpx_handle_bd_fault(void); - -static inline int kernel_managing_mpx_tables(struct mm_struct *mm) -{ - return (mm->context.bd_addr != MPX_INVALID_BOUNDS_DIR); -} - -static inline void mpx_mm_init(struct mm_struct *mm) -{ - /* - * NULL is theoretically a valid place to put the bounds - * directory, so point this at an invalid address. - */ - mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR; -} - -extern void mpx_notify_unmap(struct mm_struct *mm, unsigned long start, unsigned long end); -extern unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len, unsigned long flags); - -#else -static inline int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs) -{ - return -EINVAL; -} -static inline int mpx_handle_bd_fault(void) -{ - return -EINVAL; -} -static inline int kernel_managing_mpx_tables(struct mm_struct *mm) -{ - return 0; -} -static inline void mpx_mm_init(struct mm_struct *mm) -{ -} -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 54f5d54280f6..4482f14dc48d 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -915,24 +915,6 @@ extern int set_tsc_mode(unsigned int val); DECLARE_PER_CPU(u64, msr_misc_features_shadow); -/* Register/unregister a process' MPX related resource */ -#define MPX_ENABLE_MANAGEMENT() mpx_enable_management() -#define MPX_DISABLE_MANAGEMENT() mpx_disable_management() - -#ifdef CONFIG_X86_INTEL_MPX -extern int mpx_enable_management(void); -extern int mpx_disable_management(void); -#else -static inline int mpx_enable_management(void) -{ - return -EINVAL; -} -static inline int mpx_disable_management(void) -{ - return -EINVAL; -} -#endif /* CONFIG_X86_INTEL_MPX */ - #ifdef CONFIG_CPU_SUP_AMD extern u16 amd_get_nb_id(int cpu); extern u32 amd_get_nodes_per_socket(void); diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h deleted file mode 100644 index 54133017267c..000000000000 --- a/arch/x86/include/asm/trace/mpx.h +++ /dev/null @@ -1,134 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#undef TRACE_SYSTEM -#define TRACE_SYSTEM mpx - -#if !defined(_TRACE_MPX_H) || defined(TRACE_HEADER_MULTI_READ) -#define _TRACE_MPX_H - -#include <linux/tracepoint.h> - -#ifdef CONFIG_X86_INTEL_MPX - -TRACE_EVENT(mpx_bounds_register_exception, - - TP_PROTO(void __user *addr_referenced, - const struct mpx_bndreg *bndreg), - TP_ARGS(addr_referenced, bndreg), - - TP_STRUCT__entry( - __field(void __user *, addr_referenced) - __field(u64, lower_bound) - __field(u64, upper_bound) - ), - - TP_fast_assign( - __entry->addr_referenced = addr_referenced; - __entry->lower_bound = bndreg->lower_bound; - __entry->upper_bound = bndreg->upper_bound; - ), - /* - * Note that we are printing out the '~' of the upper - * bounds register here. It is actually stored in its - * one's complement form so that its 'init' state - * corresponds to all 0's. But, that looks like - * gibberish when printed out, so print out the 1's - * complement instead of the actual value here. Note - * though that you still need to specify filters for the - * actual value, not the displayed one. - */ - TP_printk("address referenced: 0x%p bounds: lower: 0x%llx ~upper: 0x%llx", - __entry->addr_referenced, - __entry->lower_bound, - ~__entry->upper_bound - ) -); - -TRACE_EVENT(bounds_exception_mpx, - - TP_PROTO(const struct mpx_bndcsr *bndcsr), - TP_ARGS(bndcsr), - - TP_STRUCT__entry( - __field(u64, bndcfgu) - __field(u64, bndstatus) - ), - - TP_fast_assign( - /* need to get rid of the 'const' on bndcsr */ - __entry->bndcfgu = (u64)bndcsr->bndcfgu; - __entry->bndstatus = (u64)bndcsr->bndstatus; - ), - - TP_printk("bndcfgu:0x%llx bndstatus:0x%llx", - __entry->bndcfgu, - __entry->bndstatus) -); - -DECLARE_EVENT_CLASS(mpx_range_trace, - - TP_PROTO(unsigned long start, - unsigned long end), - TP_ARGS(start, end), - - TP_STRUCT__entry( - __field(unsigned long, start) - __field(unsigned long, end) - ), - - TP_fast_assign( - __entry->start = start; - __entry->end = end; - ), - - TP_printk("[0x%p:0x%p]", - (void *)__entry->start, - (void *)__entry->end - ) -); - -DEFINE_EVENT(mpx_range_trace, mpx_unmap_zap, - TP_PROTO(unsigned long start, unsigned long end), - TP_ARGS(start, end) -); - -DEFINE_EVENT(mpx_range_trace, mpx_unmap_search, - TP_PROTO(unsigned long start, unsigned long end), - TP_ARGS(start, end) -); - -TRACE_EVENT(mpx_new_bounds_table, - - TP_PROTO(unsigned long table_vaddr), - TP_ARGS(table_vaddr), - - TP_STRUCT__entry( - __field(unsigned long, table_vaddr) - ), - - TP_fast_assign( - __entry->table_vaddr = table_vaddr; - ), - - TP_printk("table vaddr:%p", (void *)__entry->table_vaddr) -); - -#else - -/* - * This gets used outside of MPX-specific code, so we need a stub. - */ -static inline -void trace_bounds_exception_mpx(const struct mpx_bndcsr *bndcsr) -{ -} - -#endif /* CONFIG_X86_INTEL_MPX */ - -#undef TRACE_INCLUDE_PATH -#define TRACE_INCLUDE_PATH asm/trace/ -#undef TRACE_INCLUDE_FILE -#define TRACE_INCLUDE_FILE mpx -#endif /* _TRACE_MPX_H */ - -/* This part must be outside protection */ -#include <trace/define_trace.h> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index fffe21945374..be2c85bf9c56 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -165,22 +165,6 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = { } }; EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); -static int __init x86_mpx_setup(char *s) -{ - /* require an exact match without trailing characters */ - if (strlen(s)) - return 0; - - /* do not emit a message if the feature is not present */ - if (!boot_cpu_has(X86_FEATURE_MPX)) - return 1; - - setup_clear_cpu_cap(X86_FEATURE_MPX); - pr_info("nompx: Intel Memory Protection Extensions (MPX) disabled\n"); - return 1; -} -__setup("nompx", x86_mpx_setup); - #ifdef CONFIG_X86_64 static int __init x86_nopcid_setup(char *s) { @@ -307,8 +291,6 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c) static __init int setup_disable_smep(char *arg) { setup_clear_cpu_cap(X86_FEATURE_SMEP); - /* Check for things that depend on SMEP being enabled: */ - check_mpx_erratum(&boot_cpu_data); return 1; } __setup("nosmep", setup_disable_smep); diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 11d5c5950e2d..ea5899f79f36 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -32,41 +32,6 @@ #endif /* - * Just in case our CPU detection goes bad, or you have a weird system, - * allow a way to override the automatic disabling of MPX. - */ -static int forcempx; - -static int __init forcempx_setup(char *__unused) -{ - forcempx = 1; - - return 1; -} -__setup("intel-skd-046-workaround=disable", forcempx_setup); - -void check_mpx_erratum(struct cpuinfo_x86 *c) -{ - if (forcempx) - return; - /* - * Turn off the MPX feature on CPUs where SMEP is not - * available or disabled. - * - * Works around Intel Erratum SKD046: "Branch Instructions - * May Initialize MPX Bound Registers Incorrectly". - * - * This might falsely disable MPX on systems without - * SMEP, like Atom processors without SMEP. But there - * is no such hardware known at the moment. - */ - if (cpu_has(c, X86_FEATURE_MPX) && !cpu_has(c, X86_FEATURE_SMEP)) { - setup_clear_cpu_cap(X86_FEATURE_MPX); - pr_warn("x86/mpx: Disabling MPX since SMEP not present\n"); - } -} - -/* * Processors which have self-snooping capability can handle conflicting * memory type across CPUs by snooping its own cache. However, there exists * CPU models in which having conflicting memory types still leads to @@ -330,7 +295,6 @@ static void early_init_intel(struct cpuinfo_x86 *c) c->x86_coreid_bits = get_count_order((ebx >> 16) & 0xff); } - check_mpx_erratum(c); check_memory_type_self_snoop_errata(c); /* diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 77ea96b794bd..6cf206806be0 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -947,8 +947,6 @@ void __init setup_arch(char **cmdline_p) init_mm.end_data = (unsigned long) _edata; init_mm.brk = _brk_end; - mpx_mm_init(&init_mm); - code_resource.start = __pa_symbol(_text); code_resource.end = __pa_symbol(_etext)-1; data_resource.start = __pa_symbol(_etext); diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c index f7476ce23b6e..ca3c11a17b5a 100644 --- a/arch/x86/kernel/sys_x86_64.c +++ b/arch/x86/kernel/sys_x86_64.c @@ -22,7 +22,6 @@ #include <asm/elf.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. @@ -137,10 +136,6 @@ 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; @@ -180,10 +175,6 @@ 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 fab095362c50..5bfd5aef5378 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -19,7 +19,6 @@ #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 * @@ -151,10 +150,6 @@ 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/mmap.c b/arch/x86/mm/mmap.c index aae9a933dfd4..cb91eccc4960 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -163,8 +163,6 @@ unsigned long get_mmap_base(int is_legacy) const char *arch_vma_name(struct vm_area_struct *vma) { - if (vma->vm_flags & VM_MPX) - return "[mpx]"; return NULL; } diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c deleted file mode 100644 index 895fb7a9294d..000000000000 --- a/arch/x86/mm/mpx.c +++ /dev/null @@ -1,938 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * mpx.c - Memory Protection eXtensions - * - * Copyright (c) 2014, Intel Corporation. - * Qiaowei Ren <qiaowei.ren@intel.com> - * Dave Hansen <dave.hansen@intel.com> - */ -#include <linux/kernel.h> -#include <linux/slab.h> -#include <linux/mm_types.h> -#include <linux/mman.h> -#include <linux/syscalls.h> -#include <linux/sched/sysctl.h> - -#include <asm/insn.h> -#include <asm/insn-eval.h> -#include <asm/mmu_context.h> -#include <asm/mpx.h> -#include <asm/processor.h> -#include <asm/fpu/internal.h> - -#define CREATE_TRACE_POINTS -#include <asm/trace/mpx.h> - -static inline unsigned long mpx_bd_size_bytes(struct mm_struct *mm) -{ - if (is_64bit_mm(mm)) - return MPX_BD_SIZE_BYTES_64; - else - return MPX_BD_SIZE_BYTES_32; -} - -static inline unsigned long mpx_bt_size_bytes(struct mm_struct *mm) -{ - if (is_64bit_mm(mm)) - return MPX_BT_SIZE_BYTES_64; - else - return MPX_BT_SIZE_BYTES_32; -} - -/* - * This is really a simplified "vm_mmap". it only handles MPX - * bounds tables (the bounds directory is user-allocated). - */ -static unsigned long mpx_mmap(unsigned long len) -{ - struct mm_struct *mm = current->mm; - unsigned long addr, populate; - - /* Only bounds table can be allocated here */ - if (len != mpx_bt_size_bytes(mm)) - return -EINVAL; - - down_write(&mm->mmap_sem); - addr = do_mmap(NULL, 0, len, PROT_READ | PROT_WRITE, - MAP_ANONYMOUS | MAP_PRIVATE, VM_MPX, 0, &populate, NULL); - up_write(&mm->mmap_sem); - if (populate) - mm_populate(addr, populate); - - return addr; -} - -static int mpx_insn_decode(struct insn *insn, - struct pt_regs *regs) -{ - unsigned char buf[MAX_INSN_SIZE]; - int x86_64 = !test_thread_flag(TIF_IA32); - int not_copied; - int nr_copied; - - not_copied = copy_from_user(buf, (void __user *)regs->ip, sizeof(buf)); - nr_copied = sizeof(buf) - not_copied; - /* - * The decoder _should_ fail nicely if we pass it a short buffer. - * But, let's not depend on that implementation detail. If we - * did not get anything, just error out now. - */ - if (!nr_copied) - return -EFAULT; - insn_init(insn, buf, nr_copied, x86_64); - insn_get_length(insn); - /* - * copy_from_user() tries to get as many bytes as we could see in - * the largest possible instruction. If the instruction we are - * after is shorter than that _and_ we attempt to copy from - * something unreadable, we might get a short read. This is OK - * as long as the read did not stop in the middle of the - * instruction. Check to see if we got a partial instruction. - */ - if (nr_copied < insn->length) - return -EFAULT; - - insn_get_opcode(insn); - /* - * We only _really_ need to decode bndcl/bndcn/bndcu - * Error out on anything else. - */ - if (insn->opcode.bytes[0] != 0x0f) - goto bad_opcode; - if ((insn->opcode.bytes[1] != 0x1a) && - (insn->opcode.bytes[1] != 0x1b)) - goto bad_opcode; - - return 0; -bad_opcode: - return -EINVAL; -} - -/* - * If a bounds overflow occurs then a #BR is generated. This - * function decodes MPX instructions to get violation address - * and set this address into extended struct siginfo. - * - * Note that this is not a super precise way of doing this. - * Userspace could have, by the time we get here, written - * anything it wants in to the instructions. We can not - * trust anything about it. They might not be valid - * instructions or might encode invalid registers, etc... - */ -int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs) -{ - const struct mpx_bndreg_state *bndregs; - const struct mpx_bndreg *bndreg; - struct insn insn; - uint8_t bndregno; - int err; - - err = mpx_insn_decode(&insn, regs); - if (err) - goto err_out; - - /* - * We know at this point that we are only dealing with - * MPX instructions. - */ - insn_get_modrm(&insn); - bndregno = X86_MODRM_REG(insn.modrm.value); - if (bndregno > 3) { - err = -EINVAL; - goto err_out; - } - /* get bndregs field from current task's xsave area */ - bndregs = get_xsave_field_ptr(XFEATURE_BNDREGS); - if (!bndregs) { - err = -EINVAL; - goto err_out; - } - /* now go select the individual register in the set of 4 */ - bndreg = &bndregs->bndreg[bndregno]; - - /* - * The registers are always 64-bit, but the upper 32 - * bits are ignored in 32-bit mode. Also, note that the - * upper bounds are architecturally represented in 1's - * complement form. - * - * The 'unsigned long' cast is because the compiler - * complains when casting from integers to different-size - * pointers. - */ - info->lower = (void __user *)(unsigned long)bndreg->lower_bound; - info->upper = (void __user *)(unsigned long)~bndreg->upper_bound; - info->addr = insn_get_addr_ref(&insn, regs); - - /* - * We were not able to extract an address from the instruction, - * probably because there was something invalid in it. - */ - if (info->addr == (void __user *)-1) { - err = -EINVAL; - goto err_out; - } - trace_mpx_bounds_register_exception(info->addr, bndreg); - return 0; -err_out: - /* info might be NULL, but kfree() handles that */ - return err; -} - -static __user void *mpx_get_bounds_dir(void) -{ - const struct mpx_bndcsr *bndcsr; - - if (!cpu_feature_enabled(X86_FEATURE_MPX)) - return MPX_INVALID_BOUNDS_DIR; - - /* - * The bounds directory pointer is stored in a register - * only accessible if we first do an xsave. - */ - bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); - if (!bndcsr) - return MPX_INVALID_BOUNDS_DIR; - - /* - * Make sure the register looks valid by checking the - * enable bit. - */ - if (!(bndcsr->bndcfgu & MPX_BNDCFG_ENABLE_FLAG)) - return MPX_INVALID_BOUNDS_DIR; - - /* - * Lastly, mask off the low bits used for configuration - * flags, and return the address of the bounds table. - */ - return (void __user *)(unsigned long) - (bndcsr->bndcfgu & MPX_BNDCFG_ADDR_MASK); -} - -int mpx_enable_management(void) -{ - void __user *bd_base = MPX_INVALID_BOUNDS_DIR; - struct mm_struct *mm = current->mm; - int ret = 0; - - /* - * runtime in the userspace will be responsible for allocation of - * the bounds directory. Then, it will save the base of the bounds - * directory into XSAVE/XRSTOR Save Area and enable MPX through - * XRSTOR instruction. - * - * The copy_xregs_to_kernel() beneath get_xsave_field_ptr() is - * expected to be relatively expensive. Storing the bounds - * directory here means that we do not have to do xsave in the - * unmap path; we can just use mm->context.bd_addr instead. - */ - 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; -} - -int mpx_disable_management(void) -{ - struct mm_struct *mm = current->mm; - - if (!cpu_feature_enabled(X86_FEATURE_MPX)) - return -ENXIO; - - down_write(&mm->mmap_sem); - mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR; - up_write(&mm->mmap_sem); - return 0; -} - -static int mpx_cmpxchg_bd_entry(struct mm_struct *mm, - unsigned long *curval, - unsigned long __user *addr, - unsigned long old_val, unsigned long new_val) -{ - int ret; - /* - * user_atomic_cmpxchg_inatomic() actually uses sizeof() - * the pointer that we pass to it to figure out how much - * data to cmpxchg. We have to be careful here not to - * pass a pointer to a 64-bit data type when we only want - * a 32-bit copy. - */ - if (is_64bit_mm(mm)) { - ret = user_atomic_cmpxchg_inatomic(curval, - addr, old_val, new_val); - } else { - u32 uninitialized_var(curval_32); - u32 old_val_32 = old_val; - u32 new_val_32 = new_val; - u32 __user *addr_32 = (u32 __user *)addr; - - ret = user_atomic_cmpxchg_inatomic(&curval_32, - addr_32, old_val_32, new_val_32); - *curval = curval_32; - } - return ret; -} - -/* - * With 32-bit mode, a bounds directory is 4MB, and the size of each - * bounds table is 16KB. With 64-bit mode, a bounds directory is 2GB, - * and the size of each bounds table is 4MB. - */ -static int allocate_bt(struct mm_struct *mm, long __user *bd_entry) -{ - unsigned long expected_old_val = 0; - unsigned long actual_old_val = 0; - unsigned long bt_addr; - unsigned long bd_new_entry; - int ret = 0; - - /* - * Carve the virtual space out of userspace for the new - * bounds table: - */ - bt_addr = mpx_mmap(mpx_bt_size_bytes(mm)); - if (IS_ERR((void *)bt_addr)) - return PTR_ERR((void *)bt_addr); - /* - * Set the valid flag (kinda like _PAGE_PRESENT in a pte) - */ - bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG; - - /* - * Go poke the address of the new bounds table in to the - * bounds directory entry out in userspace memory. Note: - * we may race with another CPU instantiating the same table. - * In that case the cmpxchg will see an unexpected - * 'actual_old_val'. - * - * This can fault, but that's OK because we do not hold - * mmap_sem at this point, unlike some of the other part - * of the MPX code that have to pagefault_disable(). - */ - ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val, bd_entry, - expected_old_val, bd_new_entry); - if (ret) - goto out_unmap; - - /* - * The user_atomic_cmpxchg_inatomic() will only return nonzero - * for faults, *not* if the cmpxchg itself fails. Now we must - * verify that the cmpxchg itself completed successfully. - */ - /* - * We expected an empty 'expected_old_val', but instead found - * an apparently valid entry. Assume we raced with another - * thread to instantiate this table and desclare succecss. - */ - if (actual_old_val & MPX_BD_ENTRY_VALID_FLAG) { - ret = 0; - goto out_unmap; - } - /* - * We found a non-empty bd_entry but it did not have the - * VALID_FLAG set. Return an error which will result in - * a SEGV since this probably means that somebody scribbled - * some invalid data in to a bounds table. - */ - if (expected_old_val != actual_old_val) { - ret = -EINVAL; - goto out_unmap; - } - trace_mpx_new_bounds_table(bt_addr); - return 0; -out_unmap: - vm_munmap(bt_addr, mpx_bt_size_bytes(mm)); - return ret; -} - -/* - * When a BNDSTX instruction attempts to save bounds to a bounds - * table, it will first attempt to look up the table in the - * first-level bounds directory. If it does not find a table in - * the directory, a #BR is generated and we get here in order to - * allocate a new table. - * - * With 32-bit mode, the size of BD is 4MB, and the size of each - * bound table is 16KB. With 64-bit mode, the size of BD is 2GB, - * and the size of each bound table is 4MB. - */ -static int do_mpx_bt_fault(void) -{ - unsigned long bd_entry, bd_base; - const struct mpx_bndcsr *bndcsr; - struct mm_struct *mm = current->mm; - - bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); - if (!bndcsr) - return -EINVAL; - /* - * Mask off the preserve and enable bits - */ - bd_base = bndcsr->bndcfgu & MPX_BNDCFG_ADDR_MASK; - /* - * The hardware provides the address of the missing or invalid - * entry via BNDSTATUS, so we don't have to go look it up. - */ - bd_entry = bndcsr->bndstatus & MPX_BNDSTA_ADDR_MASK; - /* - * Make sure the directory entry is within where we think - * the directory is. - */ - if ((bd_entry < bd_base) || - (bd_entry >= bd_base + mpx_bd_size_bytes(mm))) - return -EINVAL; - - return allocate_bt(mm, (long __user *)bd_entry); -} - -int mpx_handle_bd_fault(void) -{ - /* - * Userspace never asked us to manage the bounds tables, - * so refuse to help. - */ - if (!kernel_managing_mpx_tables(current->mm)) - return -EINVAL; - - return do_mpx_bt_fault(); -} - -/* - * A thin wrapper around get_user_pages(). Returns 0 if the - * fault was resolved or -errno if not. - */ -static int mpx_resolve_fault(long __user *addr, int write) -{ - long gup_ret; - int nr_pages = 1; - - gup_ret = get_user_pages((unsigned long)addr, nr_pages, - write ? FOLL_WRITE : 0, NULL, NULL); - /* - * get_user_pages() returns number of pages gotten. - * 0 means we failed to fault in and get anything, - * probably because 'addr' is bad. - */ - if (!gup_ret) - return -EFAULT; - /* Other error, return it */ - if (gup_ret < 0) - return gup_ret; - /* must have gup'd a page and gup_ret>0, success */ - return 0; -} - -static unsigned long mpx_bd_entry_to_bt_addr(struct mm_struct *mm, - unsigned long bd_entry) -{ - unsigned long bt_addr = bd_entry; - int align_to_bytes; - /* - * Bit 0 in a bt_entry is always the valid bit. - */ - bt_addr &= ~MPX_BD_ENTRY_VALID_FLAG; - /* - * Tables are naturally aligned at 8-byte boundaries - * on 64-bit and 4-byte boundaries on 32-bit. The - * documentation makes it appear that the low bits - * are ignored by the hardware, so we do the same. - */ - if (is_64bit_mm(mm)) - align_to_bytes = 8; - else - align_to_bytes = 4; - bt_addr &= ~(align_to_bytes-1); - return bt_addr; -} - -/* - * We only want to do a 4-byte get_user() on 32-bit. Otherwise, - * we might run off the end of the bounds table if we are on - * a 64-bit kernel and try to get 8 bytes. - */ -static int get_user_bd_entry(struct mm_struct *mm, unsigned long *bd_entry_ret, - long __user *bd_entry_ptr) -{ - u32 bd_entry_32; - int ret; - - if (is_64bit_mm(mm)) - return get_user(*bd_entry_ret, bd_entry_ptr); - - /* - * Note that get_user() uses the type of the *pointer* to - * establish the size of the get, not the destination. - */ - ret = get_user(bd_entry_32, (u32 __user *)bd_entry_ptr); - *bd_entry_ret = bd_entry_32; - return ret; -} - -/* - * Get the base of bounds tables pointed by specific bounds |