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diff --git a/nsprpub/pr/src/md/unix/os_Linux_x86.s b/nsprpub/pr/src/md/unix/os_Linux_x86.s
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+// -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// PRInt32 _PR_x86_AtomicIncrement(PRInt32 *val)
+//
+// Atomically increment the integer pointed to by 'val' and return
+// the result of the increment.
+//
+ .text
+ .globl _PR_x86_AtomicIncrement
+ .align 4
+_PR_x86_AtomicIncrement:
+ movl 4(%esp), %ecx
+ movl $1, %eax
+ lock
+ xaddl %eax, (%ecx)
+ incl %eax
+ ret
+
+// PRInt32 _PR_x86_AtomicDecrement(PRInt32 *val)
+//
+// Atomically decrement the integer pointed to by 'val' and return
+// the result of the decrement.
+//
+ .text
+ .globl _PR_x86_AtomicDecrement
+ .align 4
+_PR_x86_AtomicDecrement:
+ movl 4(%esp), %ecx
+ movl $-1, %eax
+ lock
+ xaddl %eax, (%ecx)
+ decl %eax
+ ret
+
+// PRInt32 _PR_x86_AtomicSet(PRInt32 *val, PRInt32 newval)
+//
+// Atomically set the integer pointed to by 'val' to the new
+// value 'newval' and return the old value.
+//
+// An alternative implementation:
+// .text
+// .globl _PR_x86_AtomicSet
+// .align 4
+//_PR_x86_AtomicSet:
+// movl 4(%esp), %ecx
+// movl 8(%esp), %edx
+// movl (%ecx), %eax
+//retry:
+// lock
+// cmpxchgl %edx, (%ecx)
+// jne retry
+// ret
+//
+ .text
+ .globl _PR_x86_AtomicSet
+ .align 4
+_PR_x86_AtomicSet:
+ movl 4(%esp), %ecx
+ movl 8(%esp), %eax
+ xchgl %eax, (%ecx)
+ ret
+
+// PRInt32 _PR_x86_AtomicAdd(PRInt32 *ptr, PRInt32 val)
+//
+// Atomically add 'val' to the integer pointed to by 'ptr'
+// and return the result of the addition.
+//
+ .text
+ .globl _PR_x86_AtomicAdd
+ .align 4
+_PR_x86_AtomicAdd:
+ movl 4(%esp), %ecx
+ movl 8(%esp), %eax
+ movl %eax, %edx
+ lock
+ xaddl %eax, (%ecx)
+ addl %edx, %eax
+ ret
+
+// Magic indicating no need for an executable stack
+.section .note.GNU-stack, "", @progbits ; .previous