sim-se: Add prlimit system call

Some ISAs (namely RISC-V) implement getrlimit and setrlimit using
prlimit. This patch adds an implementation for the prlimit system call.
Normally prlimit is supposed to provide the functionality of both
getrlimit and setrlimit, but because gem5 does not support setrlimit
this implementation of prlimit will simply display a warning and return
a failure code if the setrlimit mode is used. The same thing will happen
if a pid other than 0 is passed to it.

Change-Id: I653af2d5a60e716f4d6286196be7600409efcef8
Reviewed-on: https://gem5-review.googlesource.com/5321
Maintainer: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh
index fa0959f0e..1b4580bbf 100644
--- a/src/sim/syscall_emul.hh
+++ b/src/sim/syscall_emul.hh
@@ -1687,6 +1687,48 @@ getrlimitFunc(SyscallDesc *desc, int callnum, Process *process,
     return 0;
 }
 
+template <class OS>
+SyscallReturn
+prlimitFunc(SyscallDesc *desc, int callnum, Process *process,
+            ThreadContext *tc)
+{
+    int index = 0;
+    if (process->getSyscallArg(tc, index) != 0)
+    {
+        warn("prlimit: ignoring rlimits for nonzero pid");
+        return -EPERM;
+    }
+    int resource = process->getSyscallArg(tc, index);
+    Addr n = process->getSyscallArg(tc, index);
+    if (n != 0)
+        warn("prlimit: ignoring new rlimit");
+    Addr o = process->getSyscallArg(tc, index);
+    if (o != 0)
+    {
+        TypedBufferArg<typename OS::rlimit> rlp(
+                process->getSyscallArg(tc, index));
+        switch (resource) {
+          case OS::TGT_RLIMIT_STACK:
+            // max stack size in bytes: make up a number (8MB for now)
+            rlp->rlim_cur = rlp->rlim_max = 8 * 1024 * 1024;
+            rlp->rlim_cur = TheISA::htog(rlp->rlim_cur);
+            rlp->rlim_max = TheISA::htog(rlp->rlim_max);
+            break;
+          case OS::TGT_RLIMIT_DATA:
+            // max data segment size in bytes: make up a number
+            rlp->rlim_cur = rlp->rlim_max = 256*1024*1024;
+            rlp->rlim_cur = TheISA::htog(rlp->rlim_cur);
+            rlp->rlim_max = TheISA::htog(rlp->rlim_max);
+          default:
+            warn("prlimit: unimplemented resource %d", resource);
+            return -EINVAL;
+            break;
+        }
+        rlp.copyOut(tc->getMemProxy());
+    }
+    return 0;
+}
+
 /// Target clock_gettime() function.
 template <class OS>
 SyscallReturn