[PATCH] [PATCH V1] Add mlock2 syscall wrapper

[PATCH] [PATCH V1] Add mlock2 syscall wrapper

[Tottenham, Max]

The mlock2 syscall has been accepted upstream for kernel v4.4. This
patch adds a simple syscall wrapper to libc for x86_64 and i386.

-- Max Tottenham



---
 arch/i386/bits/mman.h      | 1 +
 arch/i386/bits/syscall.h   | 2 ++
 arch/x86_64/bits/mman.h    | 1 +
 arch/x86_64/bits/syscall.h | 2 ++
 include/sys/mman.h         | 1 +
 src/mman/mlock2.c          | 7 +++++++
 6 files changed, 14 insertions(+)
 create mode 100644 src/mman/mlock2.c


diff --git a/arch/i386/bits/mman.h b/arch/i386/bits/mman.h
index 0f53acb..0c9022f 100644
--- a/arch/i386/bits/mman.h
+++ b/arch/i386/bits/mman.h
@@ -38,6 +38,7 @@
 
 #define MCL_CURRENT     1
 #define MCL_FUTURE      2
+#define MCL_ONFAULT     4
 
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 #define MADV_NORMAL      0
diff --git a/arch/i386/bits/syscall.h b/arch/i386/bits/syscall.h
index 2902f80..168ccd7 100644
--- a/arch/i386/bits/syscall.h
+++ b/arch/i386/bits/syscall.h
@@ -357,6 +357,7 @@
 #define __NR_memfd_create	356
 #define __NR_bpf		357
 #define __NR_execveat		358
+#define __NR_mlock2		376
 
 
 /* Repeated with SYS_ prefix */
@@ -720,3 +721,4 @@
 #define SYS_memfd_create	356
 #define SYS_bpf			357
 #define SYS_execveat		358
+#define SYS_mlock2		376
diff --git a/arch/x86_64/bits/mman.h b/arch/x86_64/bits/mman.h
index 846b7ea..f3235f4 100644
--- a/arch/x86_64/bits/mman.h
+++ b/arch/x86_64/bits/mman.h
@@ -38,6 +38,7 @@
 
 #define MCL_CURRENT     1
 #define MCL_FUTURE      2
+#define MCL_ONFAULT     4
 
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 #define MADV_NORMAL      0
diff --git a/arch/x86_64/bits/syscall.h b/arch/x86_64/bits/syscall.h
index 96ec51f..ae27522 100644
--- a/arch/x86_64/bits/syscall.h
+++ b/arch/x86_64/bits/syscall.h
@@ -321,6 +321,7 @@
 #define __NR_kexec_file_load			320
 #define __NR_bpf				321
 #define __NR_execveat				322
+#define __NR_mlock2				325
 
 
 
@@ -649,3 +650,4 @@
 #define SYS_kexec_file_load			320
 #define SYS_bpf					321
 #define SYS_execveat				322
+#define SYS_mlock2				325
diff --git a/include/sys/mman.h b/include/sys/mman.h
index 9fc2db5..3c767ad 100644
--- a/include/sys/mman.h
+++ b/include/sys/mman.h
@@ -27,6 +27,7 @@ int msync (void *, size_t, int);
 int posix_madvise (void *, size_t, int);
 
 int mlock (const void *, size_t);
+int mlock2 (const void *, size_t, int);
 int munlock (const void *, size_t);
 int mlockall (int);
 int munlockall (void);
diff --git a/src/mman/mlock2.c b/src/mman/mlock2.c
new file mode 100644
index 0000000..a317f8a
--- /dev/null
+++ b/src/mman/mlock2.c
@@ -0,0 +1,7 @@
+#include <sys/mman.h>
+#include "syscall.h"
+
+int mlock2(const void *addr, size_t len, int flags)
+{
+	return syscall(SYS_mlock2, addr, len, flags);
+}
-- 
2.6.1

Re: [PATCH] [PATCH V1] Add mlock2 syscall wrapper

[Szabolcs Nagy]

* Tottenham, Max <mtottenh@akamai.com> [2015-12-10 16:49:44 +0000]:
> The mlock2 syscall has been accepted upstream for kernel v4.4. This
> patch adds a simple syscall wrapper to libc for x86_64 and i386.
> 

v4.4 is not yet tagged and i've seen new syscalls reverted
before release previously because of fundamental design flaws,
so i think we should wait until v4.4 is out.

on that note, some v4.0, v4.1, v4.2 and v4.3 patches are still
pending:
http://port70.net/~nsz/musl/linux41/
http://port70.net/~nsz/musl/linux42/
http://port70.net/~nsz/musl/linux43/