x86/mpx: remove MPX from arch/x86

From: Dave Hansen <dave.hansen@linux.intel.com>

MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).

This removes all the remaining (dead at this point) MPX handling
code remaining in the tree.  The only remaining code is the XSAVE
support for MPX state which is currently needd for KVM to handle
VMs which might use MPX.

Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>

15 files changed, 1 insertions, 1567 deletions

diff --git a/Documentation/x86/intel_mpx.rst b/Documentation/x86/intel_mpx.rst
deleted file mode 100644
index 387a640941a6..000000000000
--- a/Documentation/x86/intel_mpx.rst
+++ /dev/null
@@ -1,252 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0
-
-===========================================
-Intel(R) Memory Protection Extensions (MPX)
-===========================================
-
-Intel(R) MPX Overview
-=====================
-
-Intel(R) Memory Protection Extensions (Intel(R) MPX) is a new capability
-introduced into Intel Architecture. Intel MPX provides hardware features
-that can be used in conjunction with compiler changes to check memory
-references, for those references whose compile-time normal intentions are
-usurped at runtime due to buffer overflow or underflow.
-
-You can tell if your CPU supports MPX by looking in /proc/cpuinfo::
-
-	cat /proc/cpuinfo  | grep ' mpx '
-
-For more information, please refer to Intel(R) Architecture Instruction
-Set Extensions Programming Reference, Chapter 9: Intel(R) Memory Protection
-Extensions.
-
-Note: As of December 2014, no hardware with MPX is available but it is
-possible to use SDE (Intel(R) Software Development Emulator) instead, which
-can be downloaded from
-http://software.intel.com/en-us/articles/intel-software-development-emulator
-
-
-How to get the advantage of MPX
-===============================
-
-For MPX to work, changes are required in the kernel, binutils and compiler.
-No source changes are required for applications, just a recompile.
-
-There are a lot of moving parts of this to all work right. The following
-is how we expect the compiler, application and kernel to work together.
-
-1) Application developer compiles with -fmpx. The compiler will add the
-   instrumentation as well as some setup code called early after the app
-   starts. New instruction prefixes are noops for old CPUs.
-2) That setup code allocates (virtual) space for the "bounds directory",
-   points the "bndcfgu" register to the directory (must also set the valid
-   bit) and notifies the kernel (via the new prctl(PR_MPX_ENABLE_MANAGEMENT))
-   that the app will be using MPX.  The app must be careful not to access
-   the bounds tables between the time when it populates "bndcfgu" and
-   when it calls the prctl().  This might be hard to guarantee if the app
-   is compiled with MPX.  You can add "__attribute__((bnd_legacy))" to
-   the function to disable MPX instrumentation to help guarantee this.
-   Also be careful not to call out to any other code which might be
-   MPX-instrumented.
-3) The kernel detects that the CPU has MPX, allows the new prctl() to
-   succeed, and notes the location of the bounds directory. Userspace is
-   expected to keep the bounds directory at that location. We note it
-   instead of reading it each time because the 'xsave' operation needed
-   to access the bounds directory register is an expensive operation.
-4) If the application needs to spill bounds out of the 4 registers, it
-   issues a bndstx instruction. Since the bounds directory is empty at
-   this point, a bounds fault (#BR) is raised, the kernel allocates a
-   bounds table (in the user address space) and makes the relevant entry
-   in the bounds directory point to the new table.
-5) If the application violates the bounds specified in the bounds registers,
-   a separate kind of #BR is raised which will deliver a signal with
-   information about the violation in the 'struct siginfo'.
-6) Whenever memory is freed, we know that it can no longer contain valid
-   pointers, and we attempt to free the associated space in the bounds
-   tables. If an entire table becomes unused, we will attempt to free
-   the table and remove the entry in the directory.
-
-To summarize, there are essentially three things interacting here:
-
-GCC with -fmpx:
- * enables annotation of code with MPX instructions and prefixes
- * inserts code early in the application to call in to the "gcc runtime"
-GCC MPX Runtime:
- * Checks for hardware MPX support in cpuid leaf
- * allocates virtual space for the bounds directory (malloc() essentially)
- * points the hardware BNDCFGU register at the directory
- * calls a new prctl(PR_MPX_ENABLE_MANAGEMENT) to notify the kernel to
-   start managing the bounds directories
-Kernel MPX Code:
- * Checks for hardware MPX support in cpuid leaf
- * Handles #BR exceptions and sends SIGSEGV to the app when it violates
-   bounds, like during a buffer overflow.
- * When bounds are spilled in to an unallocated bounds table, the kernel
-   notices in the #BR exception, allocates the virtual space, then
-   updates the bounds directory to point to the new table. It keeps
-   special track of the memory with a VM_MPX flag.
- * Frees unused bounds tables at the time that the memory they described
-   is unmapped.
-
-
-How does MPX kernel code work
-=============================
-
-Handling #BR faults caused by MPX
----------------------------------
-
-When MPX is enabled, there are 2 new situations that can generate
-#BR faults.
-
-  * new bounds tables (BT) need to be allocated to save bounds.
-  * bounds violation caused by MPX instructions.
-
-We hook #BR handler to handle these two new situations.
-
-On-demand kernel allocation of bounds tables
---------------------------------------------
-
-MPX only has 4 hardware registers for storing bounds information. If
-MPX-enabled code needs more than these 4 registers, it needs to spill
-them somewhere. It has two special instructions for this which allow
-the bounds to be moved between the bounds registers and some new "bounds
-tables".
-
-#BR exceptions are a new class of exceptions just for MPX. They are
-similar conceptually to a page fault and will be raised by the MPX
-hardware during both bounds violations or when the tables are not
-present. The kernel handles those #BR exceptions for not-present tables
-by carving the space out of the normal processes address space and then
-pointing the bounds-directory over to it.
-
-The tables need to be accessed and controlled by userspace because
-the instructions for moving bounds in and out of them are extremely
-frequent. They potentially happen every time a register points to
-memory. Any direct kernel involvement (like a syscall) to access the
-tables would obviously destroy performance.
-
-Why not do this in userspace? MPX does not strictly require anything in
-the kernel. It can theoretically be done completely from userspace. Here
-are a few ways this could be done. We don't think any of them are practical
-in the real-world, but here they are.
-
-:Q: Can virtual space simply be reserved for the bounds tables so that we
-    never have to allocate them?
-:A: MPX-enabled application will possibly create a lot of bounds tables in
-    process address space to save bounds information. These tables can take
-    up huge swaths of memory (as much as 80% of the memory on the system)
-    even if we clean them up aggressively. In the worst-case scenario, the
-    tables can be 4x the size of the data structure being tracked. IOW, a
-    1-page structure can require 4 bounds-table pages. An X-GB virtual
-    area needs 4*X GB of virtual space, plus 2GB for the bounds directory.
-    If we were to preallocate them for the 128TB of user virtual address
-    space, we would need to reserve 512TB+2GB, which is larger than the
-    entire virtual address space today. This means they can not be reserved
-    ahead of time. Also, a single process's pre-populated bounds directory
-    consumes 2GB of virtual *AND* physical memory. IOW, it's completely
-    infeasible to prepopulate bounds directories.
-
-:Q: Can we preallocate bounds table space at the same time memory is
-    allocated which might contain pointers that might eventually need
-    bounds tables?
-:A: This would work if we could hook the site of each and every memory
-    allocation syscall. This can be done for small, constrained applications.
-    But, it isn't practical at a larger scale since a given app has no
-    way of controlling how all the parts of the app might allocate memory
-    (think libraries). The kernel is really the only place to intercept
-    these calls.
-
-:Q: Could a bounds fault be handed to userspace and the tables allocated
-    there in a signal handler instead of in the kernel?
-:A: mmap() is not on the list of safe async handler functions and even
-    if mmap() would work it still requires locking or nasty tricks to
-    keep track of the allocation state there.
-
-Having ruled out all of the userspace-only approaches for managing
-bounds tables that we could think of, we create them on demand in
-the kernel.
-
-Decoding MPX instructions
--------------------------
-
-If a #BR is generated due to a bounds violation caused by MPX.
-We need to decode MPX instructions to get violation address and
-set this address into extended struct siginfo.
-
-The _sigfault field of struct siginfo is extended as follow::
-
-  87		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
-  88		struct {
-  89			void __user *_addr; /* faulting insn/memory ref. */
-  90 #ifdef __ARCH_SI_TRAPNO
-  91			int _trapno;	/* TRAP # which caused the signal */
-  92 #endif
-  93			short _addr_lsb; /* LSB of the reported address */
-  94			struct {
-  95				void __user *_lower;
-  96				void __user *_upper;
-  97			} _addr_bnd;
-  98		} _sigfault;
-
-The '_addr' field refers to violation address, and new '_addr_and'
-field refers to the upper/lower bounds when a #BR is caused.
-
-Glibc will be also updated to support this new siginfo. So user
-can get violation address and bounds when bounds violations occur.
-
-Cleanup unused bounds tables
-----------------------------
-
-When a BNDSTX instruction attempts to save bounds to a bounds directory
-entry marked as invalid, a #BR is generated. This is an indication that
-no bounds table exists for this entry. In this case the fault handler
-will allocate a new bounds table on demand.
-
-Since the kernel allocated those tables on-demand without userspace
-knowledge, it is also responsible for freeing them when the associated
-mappings go away.
-
-Here, the solution for this issue is to hook do_munmap() to check
-whether one process is MPX enabled. If yes, those bounds tables covered
-in the virtual address region which is being unmapped will be freed also.
-
-Adding new prctl commands
--------------------------
-
-Two new prctl commands are added to enable and disable MPX bounds tables
-management in kernel.
-::
-
-  155	#define PR_MPX_ENABLE_MANAGEMENT	43
-  156	#define PR_MPX_DISABLE_MANAGEMENT	44
-
-Runtime library in userspace is responsible for allocation of bounds
-directory. So kernel have to use XSAVE instruction to get the base
-of bounds directory from BNDCFG register.
-
-But XSAVE is expected to be very expensive. In order to do performance
-optimization, we have to get the base of bounds directory and save it
-into struct mm_struct to be used in future during PR_MPX_ENABLE_MANAGEMENT
-command execution.
-
-
-Special rules
-=============
-
-1) If userspace is requesting help from the kernel to do the management
-of bounds tables, it may not create or modify entries in the bounds directory.
-
-Certainly users can allocate bounds tables and forcibly point the bounds
-directory at them through XSAVE instruction, and then set valid bit
-of bounds entry to have this entry valid.  But, the kernel will decline
-to assist in managing these tables.
-
-2) Userspace may not take multiple bounds directory entries and point
-them at the same bounds table.
-
-This is allowed architecturally.  See more information "Intel(R) Architecture
-Instruction Set Extensions Programming Reference" (9.3.4).
-
-However, if users did this, the kernel might be fooled in to unmapping an
-in-use bounds table since it does not recognize sharing.
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;