patch llvm and kernel net-next

[williamtu]

the latest LLVM will also check the 512 byte BPF stack size. So we fails earlier at compiling the object instead of loading to verifier. Patch llvm and kernel net-next to 4096.

diff --git a/lib/Target/BPF/BPFRegisterInfo.cpp b/lib/Target/BPF/BPFRegisterInfo.cpp
index 7925bee..2636acb 100644
--- a/lib/Target/BPF/BPFRegisterInfo.cpp
+++ b/lib/Target/BPF/BPFRegisterInfo.cpp
@@ -44,7 +44,7 @@ BitVector BPFRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
 
 static void WarnSize(int Offset, MachineFunction &MF, DebugLoc& DL)
 {
-  if (Offset <= -512) {
+  if (Offset <= -4096) {
       auto F = MF.getFunction();
       DiagnosticInfoUnsupported DiagStackSize(*F,
           "Looks like the BPF stack limit of 512 bytes is exceeded. "

patch kernel net-next

--- a/arch/x86/net/bpf_jit.S
+++ b/arch/x86/net/bpf_jit.S
@@ -19,7 +19,7 @@
  */
 #define SKBDATA        %r10
 #define SKF_MAX_NEG_OFF    $(-0x200000) /* SKF_LL_OFF from filter.h */
-#define MAX_BPF_STACK (512 /* from filter.h */ + \
+#define MAX_BPF_STACK (4096 /* from filter.h */ + \
        32 /* space for rbx,r13,r14,r15 */ + \
        8 /* space for skb_copy_bits */)
 
diff --git a/include/linux/filter.h b/include/linux/filter.h
index e4eb254..fb532fc 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -55,7 +55,8 @@ struct bpf_prog_aux;
 #define MAX_BPF_JIT_REG                (MAX_BPF_REG + 1)
 
 /* BPF program can access up to 512 bytes of stack space. */
-#define MAX_BPF_STACK  512
+//#define MAX_BPF_STACK        512
+#define MAX_BPF_STACK  4096
 
 #define BPF_TAG_SIZE   8