Matt Sinclair has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/48346 )
Change subject: sim-se: Properly handle a clone with the VFORK flag
......................................................................
sim-se: Properly handle a clone with the VFORK flag
When clone is called with the VFORK flag, the calling process is
suspended until the child process either exits, or calls execve.
This patch adds in a new variable to Process, which is used to store the
context of the calling process if this process is created through a
clone with VFORK set.
This patch also adds the required support in clone to suspend the
calling thread, and in exitImpl and execveFunc to wake up the calling
thread when the child thread calls either of those functions
Change-Id: I85af67544ea1d5df7102dcff1331b5a6f6f4fa7c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48346
Tested-by: kokoro <[email protected]>
Reviewed-by: Bobby R. Bruce <[email protected]>
Reviewed-by: Matt Sinclair <[email protected]>
Maintainer: Matt Sinclair <[email protected]>
---
M src/sim/process.cc
M src/sim/process.hh
M src/sim/syscall_emul.cc
M src/sim/syscall_emul.hh
4 files changed, 34 insertions(+), 0 deletions(-)
Approvals:
Matt Sinclair: Looks good to me, but someone else must approve; Looks
good to me, approved
Bobby R. Bruce: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/sim/process.cc b/src/sim/process.cc
index 207c275..272fc9f 100644
--- a/src/sim/process.cc
+++ b/src/sim/process.cc
@@ -175,6 +175,9 @@
#ifndef CLONE_THREAD
#define CLONE_THREAD 0
#endif
+#ifndef CLONE_VFORK
+#define CLONE_VFORK 0
+#endif
if (CLONE_VM & flags) {
/**
* Share the process memory address space between the new process
@@ -249,6 +252,10 @@
np->exitGroup = exitGroup;
}
+ if (CLONE_VFORK & flags) {
+ np->vforkContexts.push_back(otc->contextId());
+ }
+
np->argv.insert(np->argv.end(), argv.begin(), argv.end());
np->envp.insert(np->envp.end(), envp.begin(), envp.end());
}
diff --git a/src/sim/process.hh b/src/sim/process.hh
index 632ba90..34768a0 100644
--- a/src/sim/process.hh
+++ b/src/sim/process.hh
@@ -284,6 +284,9 @@
// Process was forked with SIGCHLD set.
bool *sigchld;
+ // Contexts to wake up when this thread exits or calls execve
+ std::vector<ContextID> vforkContexts;
+
// Track how many system calls are executed
statistics::Scalar numSyscalls;
};
diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc
index 147cb39..713bec4 100644
--- a/src/sim/syscall_emul.cc
+++ b/src/sim/syscall_emul.cc
@@ -193,6 +193,16 @@
}
}
+ /**
+ * If we were a thread created by a clone with vfork set, wake up
+ * the thread that created us
+ */
+ if (!p->vforkContexts.empty()) {
+ ThreadContext *vtc = sys->threads[p->vforkContexts.front()];
+ assert(vtc->status() == ThreadContext::Suspended);
+ vtc->activate();
+ }
+
tc->halt();
/**
diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh
index 09be700..8695638 100644
--- a/src/sim/syscall_emul.hh
+++ b/src/sim/syscall_emul.hh
@@ -1521,6 +1521,10 @@
ctc->pcState(cpc);
ctc->activate();
+ if (flags & OS::TGT_CLONE_VFORK) {
+ tc->suspend();
+ }
+
return cp->pid();
}
@@ -1998,6 +2002,16 @@
};
/**
+ * If we were a thread created by a clone with vfork set, wake up
+ * the thread that created us
+ */
+ if (!p->vforkContexts.empty()) {
+ ThreadContext *vtc = p->system->threads[p->vforkContexts.front()];
+ assert(vtc->status() == ThreadContext::Suspended);
+ vtc->activate();
+ }
+
+ /**
* Note that ProcessParams is generated by swig and there are no other
* examples of how to create anything but this default constructor. The
* fields are manually initialized instead of passing parameters to the
--
To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/48346
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Gerrit-Project: public/gem5
Gerrit-Branch: release-staging-v21-1
Gerrit-Change-Id: I85af67544ea1d5df7102dcff1331b5a6f6f4fa7c
Gerrit-Change-Number: 48346
Gerrit-PatchSet: 3
Gerrit-Owner: Kyle Roarty <[email protected]>
Gerrit-Reviewer: Bobby R. Bruce <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Matt Sinclair <[email protected]>
Gerrit-Reviewer: Matthew Poremba <[email protected]>
Gerrit-Reviewer: kokoro <[email protected]>
Gerrit-MessageType: merged
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