[bpf] error when unknown bpf helper is called
Emit error when BPF backend sees a call to a global function or to an external symbol.
The kernel verifier only allows calls to predefined helpers from bpf.h
which are defined in 'enum bpf_func_id'. Such calls in assembler must
look like 'call [1-9]+' where number matches bpf_func_id.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
llvm-svn: 292204
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp b/llvm/lib/Target/BPF/BPFISelLowering.cpp
index cca3492..b222022 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -33,7 +33,7 @@
#define DEBUG_TYPE "bpf-lower"
-static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *Msg) {
+static void fail(const SDLoc &DL, SelectionDAG &DAG, const Twine &Msg) {
MachineFunction &MF = DAG.getMachineFunction();
DAG.getContext()->diagnose(
DiagnosticInfoUnsupported(*MF.getFunction(), Msg, DL.getDebugLoc()));
@@ -306,11 +306,23 @@
// If the callee is a GlobalAddress node (quite common, every direct call is)
// turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
// Likewise ExternalSymbol -> TargetExternalSymbol.
- if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
+ if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
+ auto GV = G->getGlobal();
+ Twine Msg("A call to global function '" + StringRef(GV->getName())
+ + "' is not supported. "
+ + (GV->isDeclaration() ?
+ "Only calls to predefined BPF helpers are allowed." :
+ "Please use __attribute__((always_inline) to make sure"
+ " this function is inlined."));
+ fail(CLI.DL, DAG, Msg);
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), CLI.DL, PtrVT,
G->getOffset(), 0);
- else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
+ } else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee)) {
Callee = DAG.getTargetExternalSymbol(E->getSymbol(), PtrVT, 0);
+ fail(CLI.DL, DAG, Twine("A call to built-in function '"
+ + StringRef(E->getSymbol())
+ + "' is not supported."));
+ }
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
diff --git a/llvm/lib/Target/BPF/BPFInstrInfo.td b/llvm/lib/Target/BPF/BPFInstrInfo.td
index a7910de..93ee243 100644
--- a/llvm/lib/Target/BPF/BPFInstrInfo.td
+++ b/llvm/lib/Target/BPF/BPFInstrInfo.td
@@ -470,6 +470,7 @@
// Calls
def : Pat<(BPFcall tglobaladdr:$dst), (JAL tglobaladdr:$dst)>;
+def : Pat<(BPFcall texternalsym:$dst), (JAL texternalsym:$dst)>;
def : Pat<(BPFcall imm:$dst), (JAL imm:$dst)>;
// Loads
diff --git a/llvm/lib/Target/BPF/BPFMCInstLower.cpp b/llvm/lib/Target/BPF/BPFMCInstLower.cpp
index f64defe..1faa1c0 100644
--- a/llvm/lib/Target/BPF/BPFMCInstLower.cpp
+++ b/llvm/lib/Target/BPF/BPFMCInstLower.cpp
@@ -29,6 +29,11 @@
return Printer.getSymbol(MO.getGlobal());
}
+MCSymbol *
+BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
+ return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
+}
+
MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
MCSymbol *Sym) const {
@@ -66,6 +71,9 @@
break;
case MachineOperand::MO_RegisterMask:
continue;
+ case MachineOperand::MO_ExternalSymbol:
+ MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
+ break;
case MachineOperand::MO_GlobalAddress:
MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
break;
diff --git a/llvm/lib/Target/BPF/BPFMCInstLower.h b/llvm/lib/Target/BPF/BPFMCInstLower.h
index 054e894..eac811f 100644
--- a/llvm/lib/Target/BPF/BPFMCInstLower.h
+++ b/llvm/lib/Target/BPF/BPFMCInstLower.h
@@ -37,6 +37,7 @@
MCOperand LowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym) const;
MCSymbol *GetGlobalAddressSymbol(const MachineOperand &MO) const;
+ MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
};
}