sim-se: adding pipe2 syscall

pipe2 builds on top of the pipe syscall implementation by
adding some extra flags for the files (to avoid have to
make separate calls to fcntl).

Change-Id: I88cf6f1387b9d14e60b33a32db412da9ed93a3e6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/12310
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Brandon Potter <Brandon.Potter@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>

2 files changed, 61 insertions, 4 deletions

diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc
index 142292d1f..28e3e3ded 100644
--- a/src/sim/syscall_emul.cc
+++ b/src/sim/syscall_emul.cc
@@ -866,13 +866,18 @@ fcntl64Func(SyscallDesc *desc, int num, ThreadContext *tc)
 }
 
 SyscallReturn
-pipeImpl(SyscallDesc *desc, int callnum, ThreadContext *tc, bool pseudoPipe)
+pipeImpl(SyscallDesc *desc, int callnum, ThreadContext *tc, bool pseudo_pipe,
+         bool is_pipe2)
 {
     Addr tgt_addr = 0;
+    int flags = 0;
     auto p = tc->getProcessPtr();
-    if (!pseudoPipe) {
+    if (!pseudo_pipe) {
         int index = 0;
         tgt_addr = p->getSyscallArg(tc, index);
+        if (is_pipe2) {
+            flags = p->getSyscallArg(tc, index);
+        }
     }
 
     int sim_fds[2], tgt_fds[2];
@@ -884,10 +889,12 @@ pipeImpl(SyscallDesc *desc, int callnum, ThreadContext *tc, bool pseudoPipe)
     auto rend = PipeFDEntry::EndType::read;
     auto rpfd = std::make_shared<PipeFDEntry>(sim_fds[0], O_WRONLY, rend);
     tgt_fds[0] = p->fds->allocFD(rpfd);
+    int sim_fd_rpfd = rpfd->getSimFD();
 
     auto wend = PipeFDEntry::EndType::write;
     auto wpfd = std::make_shared<PipeFDEntry>(sim_fds[1], O_RDONLY, wend);
     tgt_fds[1] = p->fds->allocFD(wpfd);
+    int sim_fd_wpfd = wpfd->getSimFD();
 
     /**
      * Now patch the read object to record the target file descriptor chosen
@@ -899,7 +906,7 @@ pipeImpl(SyscallDesc *desc, int callnum, ThreadContext *tc, bool pseudoPipe)
      * Alpha Linux convention for pipe() is that fd[0] is returned as
      * the return value of the function, and fd[1] is returned in r20.
      */
-    if (pseudoPipe) {
+    if (pseudo_pipe) {
         tc->setIntReg(SyscallPseudoReturnReg, tgt_fds[1]);
         return tgt_fds[0];
     }
@@ -913,6 +920,45 @@ pipeImpl(SyscallDesc *desc, int callnum, ThreadContext *tc, bool pseudoPipe)
     buf_ptr[0] = tgt_fds[0];
     buf_ptr[1] = tgt_fds[1];
     tgt_handle.copyOut(tc->getVirtProxy());
+
+    // pipe2 has additional behavior if flags != 0
+    if (is_pipe2 && flags) {
+        // pipe2 only uses O_NONBLOCK, O_CLOEXEC, and (O_NONBLOCK | O_CLOEXEC)
+        // if flags set to anything else, return EINVAL
+        if ((flags != O_CLOEXEC) && (flags != O_NONBLOCK) &&
+            (flags != (O_CLOEXEC | O_NONBLOCK))) {
+            return -EINVAL;
+        }
+
+        /*
+          If O_NONBLOCK is passed in as a flag to pipe2, set O_NONBLOCK file
+          status flag for two new open file descriptors.
+        */
+        if (flags & O_NONBLOCK) {
+            /*
+              O_NONBLOCK is set when the programmer wants to avoid a separate
+              call(s) to fcntl in their code, so mirror the fcntl
+              implementation for handling file descriptors -- rely on host to
+              maintain file status flags.
+            */
+            if (fcntl(sim_fd_rpfd, F_SETFL, O_NONBLOCK)) {
+                return -errno;
+            }
+            if (fcntl(sim_fd_wpfd, F_SETFL, O_NONBLOCK)) {
+                return -errno;
+            }
+        }
+
+        /*
+          If O_CLOEXEC is passed in as a flag to pipe2, set close-on-exec
+          (FD_CLOEXEC) file status flag for two new open file descriptors.
+        */
+        if (flags & O_CLOEXEC) {
+            rpfd->setCOE(true);
+            wpfd->setCOE(true);
+        }
+    }
+
     return 0;
 }
 
@@ -929,6 +975,14 @@ pipeFunc(SyscallDesc *desc, int callnum, ThreadContext *tc)
 }
 
 SyscallReturn
+pipe2Func(SyscallDesc *desc, int callnum, ThreadContext *tc)
+{
+    // call pipeImpl since the only difference between pipe and pipe2 is
+    // the flags values and what they do (at the end of pipeImpl)
+    return pipeImpl(desc, callnum, tc, false, true);
+}
+
+SyscallReturn
 setpgidFunc(SyscallDesc *desc, int callnum, ThreadContext *tc)
 {
     int index = 0;
diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh
index e2f2fc200..875f565cd 100644
--- a/src/sim/syscall_emul.hh
+++ b/src/sim/syscall_emul.hh
@@ -252,7 +252,10 @@ SyscallReturn pipeFunc(SyscallDesc *desc, int num, ThreadContext *tc);
 
 /// Internal pipe() handler.
 SyscallReturn pipeImpl(SyscallDesc *desc, int num, ThreadContext *tc,
-                       bool pseudoPipe);
+                       bool pseudo_pipe, bool is_pipe2=false);
+
+/// Target pipe() handler.
+SyscallReturn pipe2Func(SyscallDesc *desc, int num, ThreadContext *tc);
 
 /// Target getpid() handler.
 SyscallReturn getpidFunc(SyscallDesc *desc, int num, ThreadContext *tc);