3 files changed, 74 insertions, 6 deletions

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b650cde3f64d..50d950771371 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -48,6 +48,7 @@
 #include <asm/frame.h>
 #include <asm/unwind.h>
 #include <asm/tdx.h>
+#include <asm/mmu_context.h>
 
 #include "process.h"
 
@@ -162,6 +163,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 
 	savesegment(es, p->thread.es);
 	savesegment(ds, p->thread.ds);
+
+	if (p->mm && (clone_flags & (CLONE_VM | CLONE_VFORK)) == CLONE_VM)
+		set_bit(MM_CONTEXT_LOCK_LAM, &p->mm->context.flags);
 #else
 	p->thread.sp0 = (unsigned long) (childregs + 1);
 	savesegment(gs, p->thread.gs);
@@ -368,6 +372,8 @@ void arch_setup_new_exec(void)
 		task_clear_spec_ssb_noexec(current);
 		speculation_ctrl_update(read_thread_flags());
 	}
+
+	mm_reset_untag_mask(current->mm);
 }
 
 #ifdef CONFIG_X86_IOPL_IOPERM
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index bb65a68b4b49..223b223f713f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -671,7 +671,7 @@ void set_personality_64bit(void)
 	task_pt_regs(current)->orig_ax = __NR_execve;
 	current_thread_info()->status &= ~TS_COMPAT;
 	if (current->mm)
-		current->mm->context.flags = MM_CONTEXT_HAS_VSYSCALL;
+		__set_bit(MM_CONTEXT_HAS_VSYSCALL, &current->mm->context.flags);
 
 	/* TBD: overwrites user setup. Should have two bits.
 	   But 64bit processes have always behaved this way,
@@ -708,7 +708,7 @@ static void __set_personality_ia32(void)
 		 * uprobes applied to this MM need to know this and
 		 * cannot use user_64bit_mode() at that time.
 		 */
-		current->mm->context.flags = MM_CONTEXT_UPROBE_IA32;
+		__set_bit(MM_CONTEXT_UPROBE_IA32, &current->mm->context.flags);
 	}
 
 	current->personality |= force_personality32;
@@ -743,6 +743,52 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr)
 }
 #endif
 
+#ifdef CONFIG_ADDRESS_MASKING
+
+#define LAM_U57_BITS 6
+
+static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits)
+{
+	if (!cpu_feature_enabled(X86_FEATURE_LAM))
+		return -ENODEV;
+
+	/* PTRACE_ARCH_PRCTL */
+	if (current->mm != mm)
+		return -EINVAL;
+
+	if (mm_valid_pasid(mm) &&
+	    !test_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &mm->context.flags))
+		return -EINVAL;
+
+	if (mmap_write_lock_killable(mm))
+		return -EINTR;
+
+	if (test_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags)) {
+		mmap_write_unlock(mm);
+		return -EBUSY;
+	}
+
+	if (!nr_bits) {
+		mmap_write_unlock(mm);
+		return -EINVAL;
+	} else if (nr_bits <= LAM_U57_BITS) {
+		mm->context.lam_cr3_mask = X86_CR3_LAM_U57;
+		mm->context.untag_mask =  ~GENMASK(62, 57);
+	} else {
+		mmap_write_unlock(mm);
+		return -EINVAL;
+	}
+
+	write_cr3(__read_cr3() | mm->context.lam_cr3_mask);
+	set_tlbstate_lam_mode(mm);
+	set_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags);
+
+	mmap_write_unlock(mm);
+
+	return 0;
+}
+#endif
+
 long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
 {
 	int ret = 0;
@@ -830,7 +876,23 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
 	case ARCH_MAP_VDSO_64:
 		return prctl_map_vdso(&vdso_image_64, arg2);
 #endif
-
+#ifdef CONFIG_ADDRESS_MASKING
+	case ARCH_GET_UNTAG_MASK:
+		return put_user(task->mm->context.untag_mask,
+				(unsigned long __user *)arg2);
+	case ARCH_ENABLE_TAGGED_ADDR:
+		return prctl_enable_tagged_addr(task->mm, arg2);
+	case ARCH_FORCE_TAGGED_SVA:
+		if (current != task)
+			return -EINVAL;
+		set_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &task->mm->context.flags);
+		return 0;
+	case ARCH_GET_MAX_TAG_BITS:
+		if (!cpu_feature_enabled(X86_FEATURE_LAM))
+			return put_user(0, (unsigned long __user *)arg2);
+		else
+			return put_user(LAM_U57_BITS, (unsigned long __user *)arg2);
+#endif
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index d317dc3d06a3..8b83d8fbce71 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -671,15 +671,15 @@ static bool try_fixup_enqcmd_gp(void)
 	if (!cpu_feature_enabled(X86_FEATURE_ENQCMD))
 		return false;
 
-	pasid = current->mm->pasid;
-
 	/*
 	 * If the mm has not been allocated a
 	 * PASID, the #GP can not be fixed up.
 	 */
-	if (!pasid_valid(pasid))
+	if (!mm_valid_pasid(current->mm))
 		return false;
 
+	pasid = current->mm->pasid;
+
 	/*
 	 * Did this thread already have its PASID activated?
 	 * If so, the #GP must be from something else.