bpf.lua: Add support for CFLAGS and LLVM debug flags

examples/lua/bashreadline.lua

@@ -16,7 +16,7 @@ limitations under the License.
 local ffi = require("ffi")
 
 return function(BPF)
-  local b = BPF:new{src_file="bashreadline.c", debug=true}
+  local b = BPF:new{src_file="bashreadline.c", debug=0}
   b:attach_uprobe{name="/bin/bash", sym="readline", fn_name="printret", retprobe=true}
 
   local function print_readline(cpu, event)

examples/lua/memleak.lua

@@ -123,7 +123,7 @@ return function(BPF, utils)
   text = text:gsub("SHOULD_PRINT", args.trace and "1" or "0")
   text = text:gsub("SAMPLE_EVERY_N", tostring(args.sample_rate))
 
-  local bpf = BPF:new{text=text, debug=true}
+  local bpf = BPF:new{text=text, debug=0}
   local syms = nil
   local min_age_ns = args.older * 1e6
 

examples/lua/strlen_count.lua

@@ -32,7 +32,7 @@ int printarg(struct pt_regs *ctx) {
 ]], "PID", arg[1])
 
 return function(BPF)
-  local b = BPF:new{text=program, debug=true}
+  local b = BPF:new{text=program, debug=0}
   b:attach_uprobe{name="c", sym="strlen", fn_name="printarg"}
 
   local pipe = b:pipe()

examples/lua/task_switch.lua

@@ -38,7 +38,7 @@ int count_sched(struct pt_regs *ctx, struct task_struct *prev) {
 ]]
 
 return function(BPF)
-  local b = BPF:new{text=program, debug=true}
+  local b = BPF:new{text=program, debug=0}
   b:attach_kprobe{event="finish_task_switch", fn_name="count_sched"}
 
   print("Press any key...")

src/lua/bcc/bpf.lua

@@ -27,6 +27,11 @@ Bpf.static.open_uprobes = {}
 Bpf.static.process_symbols = {}
 Bpf.static.KPROBE_LIMIT = 1000
 Bpf.static.tracer_pipe = nil
+Bpf.static.DEFAULT_CFLAGS = {
+  '-D__HAVE_BUILTIN_BSWAP16__',
+  '-D__HAVE_BUILTIN_BSWAP32__',
+  '-D__HAVE_BUILTIN_BSWAP64__',
+}
 
 function Bpf.static.check_probe_quota(n)
   local cur = table.count(Bpf.static.open_kprobes) + table.count(Bpf.static.open_uprobes)
@@ -101,17 +106,23 @@ function Bpf:initialize(args)
   self.funcs = {}
   self.tables = {}
 
+  local cflags = table.join(Bpf.DEFAULT_CFLAGS, args.cflags)
+  local cflags_ary = ffi.new("const char *[?]", #cflags, cflags)
+
+  local llvm_debug = args.debug or 0
+  assert(type(llvm_debug) == "number")
+
   if args.text then
     log.info("\n%s\n", args.text)
-    self.module = libbcc.bpf_module_create_c_from_string(args.text, args.llvm_debug or 0, nil, 0)
+    self.module = libbcc.bpf_module_create_c_from_string(args.text, llvm_debug, cflags_ary, #cflags)
   elseif args.src_file then
     local src = _find_file(Bpf.SCRIPT_ROOT, args.src_file)
 
     if src:ends(".b") then
       local hdr = _find_file(Bpf.SCRIPT_ROOT, args.hdr_file)
-      self.module = libbcc.bpf_module_create_b(src, hdr, args.llvm_debug or 0)
+      self.module = libbcc.bpf_module_create_b(src, hdr, llvm_debug)
     else
-      self.module = libbcc.bpf_module_create_c(src, args.llvm_debug or 0, nil, 0)
+      self.module = libbcc.bpf_module_create_c(src, llvm_debug, cflags_ary, #cflags)
     end
   end
 

src/lua/bcc/vendor/helpers.lua

@@ -65,6 +65,22 @@ function table.bsearch(list, value, mkval)
   return nil
 end
 
+function table.join(a, b)
+  assert(a)
+  if b == nil or #b == 0 then
+    return a
+  end
+
+  local res = {}
+  for _, v in ipairs(a) do
+    table.insert(res, v)
+  end
+  for _, v in ipairs(b) do
+    table.insert(res, v)
+  end
+  return res
+end
+
 function table.build(iterator_fn, build_fn)
   build_fn = (build_fn or function(arg) return arg end)
   local res = {}