X86: Add the arch_prctl system call and fix up some microcoding.

The arch_prctl system call is used to set and get the FS and GS segment
bases. The FS segment is use for TLS, so glibc needs to be able to set it
up.

--HG--
extra : convert_revision : 79501491a15967a7a862add846ff88a934fb1b37

1 files changed, 41 insertions, 1 deletions

diff --git a/src/arch/x86/linux/syscalls.cc b/src/arch/x86/linux/syscalls.cc
index efbe33dfa..1146af708 100644
--- a/src/arch/x86/linux/syscalls.cc
+++ b/src/arch/x86/linux/syscalls.cc
@@ -57,6 +57,7 @@
 
 #include "arch/x86/linux/process.hh"
 #include "arch/x86/linux/linux.hh"
+#include "arch/x86/miscregs.hh"
 #include "kern/linux/linux.hh"
 #include "sim/syscall_emul.hh"
 
@@ -80,6 +81,45 @@ unameFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     return 0;
 }
 
+static SyscallReturn
+archPrctlFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
+              ThreadContext *tc)
+{
+    enum ArchPrctlCodes
+    {
+        SetFS = 0x1002,
+        GetFS = 0x1003,
+        SetGS = 0x1001,
+        GetGS = 0x1004
+    };
+
+    //First argument is the code, second is the address
+    int code = tc->getSyscallArg(0);
+    uint64_t addr = tc->getSyscallArg(1);
+    uint64_t fsBase, gsBase;
+    TranslatingPort *p = tc->getMemPort();
+    switch(code)
+    {
+      //Each of these valid options should actually check addr.
+      case SetFS:
+        tc->setMiscRegNoEffect(MISCREG_FS_BASE, addr);
+        return 0;
+      case GetFS:
+        fsBase = tc->readMiscRegNoEffect(MISCREG_FS_BASE);
+        p->write(addr, fsBase);
+        return 0;
+      case SetGS:
+        tc->setMiscRegNoEffect(MISCREG_GS_BASE, addr);
+        return 0;
+      case GetGS:
+        gsBase = tc->readMiscRegNoEffect(MISCREG_GS_BASE);
+        p->write(addr, gsBase);
+        return 0;
+      default:
+        return -EINVAL;
+    }
+}
+
 SyscallDesc X86LinuxProcess::syscallDescs[] = {
     /*   0 */ SyscallDesc("read", readFunc),
     /*   1 */ SyscallDesc("write", writeFunc),
@@ -239,7 +279,7 @@ SyscallDesc X86LinuxProcess::syscallDescs[] = {
     /* 155 */ SyscallDesc("pivot_root", unimplementedFunc),
     /* 156 */ SyscallDesc("_sysctl", unimplementedFunc),
     /* 157 */ SyscallDesc("prctl", unimplementedFunc),
-    /* 158 */ SyscallDesc("arch_prctl", unimplementedFunc),
+    /* 158 */ SyscallDesc("arch_prctl", archPrctlFunc),
     /* 159 */ SyscallDesc("adjtimex", unimplementedFunc),
     /* 160 */ SyscallDesc("setrlimit", unimplementedFunc),
     /* 161 */ SyscallDesc("chroot", unimplementedFunc),