Shim'ing out the processor affinity function calls for the Linux kernel

src/Common/src/Interop/Unix/System.Native/Interop.SchedGetSetAffinity.cs

@@ -0,0 +1,29 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class Sys
+    {
+        internal unsafe struct CpuSetBits
+        {
+            private fixed ulong Bits[16];
+        }
+
+        [DllImport(Libraries.SystemNative, SetLastError = true)]
+        internal static extern int SchedSetAffinity(int pid, ref CpuSetBits mask);
+
+        [DllImport(Libraries.SystemNative, SetLastError = true)]
+        internal static extern int SchedGetAffinity(int pid, out CpuSetBits mask);
+
+        [DllImport(Libraries.SystemNative)]
+        internal static extern void CpuSet(int cpu, ref CpuSetBits set);
+
+        [DllImport(Libraries.SystemNative)]
+        internal static extern bool CpuIsSet(int cpu, ref CpuSetBits set);
+
+    }
+}

src/Native/Common/pal_config.h.in

@@ -15,6 +15,8 @@
 #cmakedefine01 HAVE_IN6_U
 #cmakedefine01 HAVE_IOCTL
 #cmakedefine01 HAVE_TIOCGWINSZ
+#cmakedefine01 HAVE_SCHED_GETAFFINITY
+#cmakedefine01 HAVE_SCHED_SETAFFINITY
 
 // Mac OS X has stat64, but it is deprecated since plain stat now
 // provides the same 64-bit aware struct when targeting OS X > 10.5

src/Native/System.Native/pal_process.cpp

@@ -17,6 +17,10 @@
 #include <syslog.h>
 #include <unistd.h>
 
+#if HAVE_SCHED_SETAFFINITY || HAVE_SCHED_GETAFFINITY
+#include <sched.h>
+#endif
+
 // Validate that our Signals enum values are correct for the platform
 static_assert(PAL_SIGKILL == SIGKILL, "");
 
@@ -59,6 +63,12 @@ static_assert(PAL_PRIO_PROCESS == static_cast<int>(PRIO_PROCESS), "");
 static_assert(PAL_PRIO_PGRP == static_cast<int>(PRIO_PGRP), "");
 static_assert(PAL_PRIO_USER == static_cast<int>(PRIO_USER), "");
 
+#if HAVE_SCHED_SETAFFINITY || HAVE_SCHED_GETAFFINITY
+// Validate that the number of bits in the PAL CPU affinity struct is
+// greater than or equal to the native one so we can memcpy correctly
+static_assert(sizeof(CpuSetBits) >= sizeof(cpu_set_t), "");
+#endif
+
 enum
 {
     READ_END_OF_PIPE = 0,
@@ -417,3 +427,68 @@ extern "C" char* GetCwd(char* buffer, int32_t bufferSize)
 
     return getcwd(buffer, UnsignedCast(bufferSize));
 }
+
+#if HAVE_SCHED_SETAFFINITY
+static bool ConvertPalToNativeCpuSet(const CpuSetBits& pal, cpu_set_t& native)
+{
+    if (sizeof(pal) > sizeof(native))
+    {
+        // If the PAL struct is bigger than the native struct
+        // then make sure the user hasn't put data in the 
+        // bits that would be inaccessible to the underlying OS
+        for (size_t i = sizeof(native); i < sizeof(pal); i++)
+        {
+            if (pal.Bits[i] != 0)
+                return false;
+        }
+    }
+
+    memcpy(native.__bits, pal.Bits, ARRAY_SIZE(native.__bits));
+    return true;
+}
+
+extern "C" int32_t SchedSetAffinity(int32_t pid, CpuSetBits* mask)
+{
+    assert(mask != nullptr);
+    cpu_set_t set = {};
+    if (!ConvertPalToNativeCpuSet(*mask, set))
+    {
+        errno = EINVAL;
+        return -1;
+    }
+    return sched_setaffinity(pid, sizeof(cpu_set_t), &set);
+}
+#endif
+
+#if HAVE_SCHED_GETAFFINITY
+static void ConvertNativeToPalCpuSet(const cpu_set_t& native, CpuSetBits& pal)
+{
+    pal = {};
+    memcpy(pal.Bits, native.__bits, ARRAY_SIZE(native.__bits));
+}
+
+extern "C" int32_t SchedGetAffinity(int32_t pid, CpuSetBits* mask)
+{
+    assert(mask != nullptr);
+    cpu_set_t set;
+    int32_t result = sched_getaffinity(pid, sizeof(cpu_set_t), &set);
+    if (result == 0)
+    {
+        ConvertNativeToPalCpuSet(set, *mask);
+    }
+
+    return result;
+}
+#endif
+
+#if HAVE_SCHED_GETAFFINITY || HAVE_SCHED_SETAFFINITY
+extern "C" void CpuSet(int32_t cpu, CpuSetBits* set)
+{
+    set->Bits[__CPUELT(cpu)] |= __CPUMASK(cpu);
+}
+
+extern "C" bool CpuIsSet(int32_t cpu, CpuSetBits* set)
+{
+    return (set->Bits[__CPUELT(cpu)] & __CPUMASK(cpu)) != 0;
+}
+#endif

src/Native/System.Native/pal_process.h

@@ -150,6 +150,16 @@ struct RLimit
     uint64_t MaximumLimit;
 };
 
+/**
+ * The native struct is dependent on the size of a numeric type
+ * so make it the largest possible value here and then we will 
+ * copy to native as necessary
+ */
+struct CpuSetBits
+{
+    uint64_t Bits[16]; // __CPU_SETSIZE / (8 * sizeof(int64_t))
+};
+
 /**
  * Get the current limit for the specified resource of the current process.
  * Returns 0 on success; returns -1 on failure and errno is set to the error reason.
@@ -246,3 +256,31 @@ extern "C" int32_t SetPriority(PriorityWhich which, int32_t who, int32_t nice);
  * Gets the current working directory of the currently executing process.
  */
 extern "C" char* GetCwd(char* buffer, int32_t bufferSize);
+
+#if HAVE_SCHED_SETAFFINITY
+/**
+ * Sets the CPU affinity mask for a specified thread (or the current thread if 0).
+ *
+ * Returns 0 on success; otherwise, -1 is returned and errno is set
+ */
+extern "C" int32_t SchedSetAffinity(int32_t pid, CpuSetBits* mask);
+#endif
+
+#if HAVE_SCHED_GETAFFINITY
+/**
+ * Gets the affinity mask of the specified thread (or the current thread if 0).
+ *
+ * Returns 0 on success; otherwise, -1 is returned and errno is set.
+ */
+extern "C" int32_t SchedGetAffinity(int32_t pid, CpuSetBits* mask);
+#endif
+
+#if HAVE_SCHED_GETAFFINITY || HAVE_SCHED_SETAFFINITY
+
+/**
+ * Shim's for the macros of the same name. Sets a CPU bit or 
+ * retrieves if the CPU bit is set
+ */
+extern "C" void CpuSet(int32_t cpu, CpuSetBits* set);
+extern "C" bool CpuIsSet(int32_t cpu, CpuSetBits* set);
+#endif

src/Native/configure.cmake

@@ -37,6 +37,14 @@ check_function_exists(
     ioctl
     HAVE_IOCTL)
 
+check_function_exists(
+    sched_getaffinity
+    HAVE_SCHED_GETAFFINITY)
+
+check_function_exists(
+    sched_setaffinity
+    HAVE_SCHED_SETAFFINITY)
+
 check_symbol_exists(
     TIOCGWINSZ
     "sys/ioctl.h"

src/System.Diagnostics.Process/src/System.Diagnostics.Process.csproj

@@ -268,8 +268,8 @@
     <Compile Include="$(CommonPath)\Interop\Linux\procfs\Interop.ProcFsStat.cs">
       <Link>Common\Interop\Linux\Interop.ProcFsStat.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)\Interop\Linux\libc\Interop.sched_getsetaffinity.cs">
-      <Link>Common\Interop\Linux\Interop.sched_getsetaffinity.cs</Link>
+    <Compile Include="$(CommonPath)\Interop\Unix\System.Native\Interop.SchedGetSetAffinity.cs">
+      <Link>Common\Interop\Linux\Interop.SchedGetSetAffinity.cs</Link>
     </Compile>
     <Compile Include="$(CommonPath)\System\Collections\Generic\EnumerableHelpers.cs">
       <Link>Common\System\Collections\Generic\EnumerableHelpers.cs</Link>

src/System.Diagnostics.Process/src/System/Diagnostics/Process.Linux.cs

@@ -91,8 +91,8 @@ private unsafe IntPtr ProcessorAffinityCore
             {
                 EnsureState(State.HaveId);
 
-                Interop.libc.cpu_set_t set = default(Interop.libc.cpu_set_t);
-                if (Interop.libc.sched_getaffinity(_processId, (IntPtr)sizeof(Interop.libc.cpu_set_t), &set) != 0)
+                Interop.Sys.CpuSetBits set = default(Interop.Sys.CpuSetBits);
+                if (Interop.Sys.SchedGetAffinity(_processId, out set) != 0)
                 {
                     throw new Win32Exception(); // match Windows exception
                 }
@@ -101,7 +101,7 @@ private unsafe IntPtr ProcessorAffinityCore
                 int maxCpu = IntPtr.Size == 4 ? 32 : 64;
                 for (int cpu = 0; cpu < maxCpu; cpu++)
                 {
-                    if (Interop.libc.CPU_ISSET(cpu, &set))
+                    if (Interop.Sys.CpuIsSet(cpu, ref set))
                         bits |= (1u << cpu);
                 }
                 return (IntPtr)bits;
@@ -110,17 +110,17 @@ private unsafe IntPtr ProcessorAffinityCore
             {
                 EnsureState(State.HaveId);
 
-                Interop.libc.cpu_set_t set = default(Interop.libc.cpu_set_t);
+                Interop.Sys.CpuSetBits set = default(Interop.Sys.CpuSetBits);
 
                 long bits = (long)value;
                 int maxCpu = IntPtr.Size == 4 ? 32 : 64;
                 for (int cpu = 0; cpu < maxCpu; cpu++)
                 {
                     if ((bits & (1u << cpu)) != 0)
-                        Interop.libc.CPU_SET(cpu, &set);
+                        Interop.Sys.CpuSet(cpu, ref set);
                 }
 
-                if (Interop.libc.sched_setaffinity(_processId, (IntPtr)sizeof(Interop.libc.cpu_set_t), &set) != 0)
+                if (Interop.Sys.SchedSetAffinity(_processId, ref set) != 0)
                 {
                     throw new Win32Exception(); // match Windows exception
                 }