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irbuilderbpf.cpp
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#include <iostream>
#include <sstream>
#include "arch/arch.h"
#include "ast/async_event_types.h"
#include "bpftrace.h"
#include "codegen_helper.h"
#include "irbuilderbpf.h"
#include "log.h"
#include "utils.h"
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/Module.h>
namespace libbpf {
#undef __BPF_FUNC_MAPPER
#include "libbpf/bpf.h"
} // namespace libbpf
namespace bpftrace {
namespace ast {
namespace {
std::string probeReadHelperName(libbpf::bpf_func_id id)
{
switch (id)
{
case libbpf::BPF_FUNC_probe_read:
return "probe_read";
case libbpf::BPF_FUNC_probe_read_user:
return "probe_read_user";
case libbpf::BPF_FUNC_probe_read_kernel:
return "probe_read_kernel";
case libbpf::BPF_FUNC_probe_read_str:
return "probe_read_str";
case libbpf::BPF_FUNC_probe_read_user_str:
return "probe_read_user_str";
case libbpf::BPF_FUNC_probe_read_kernel_str:
return "probe_read_kernel_str";
default:
throw std::runtime_error("BUG: unknown probe_read id: " +
std::to_string(id));
}
}
} // namespace
libbpf::bpf_func_id IRBuilderBPF::selectProbeReadHelper(AddrSpace as, bool str)
{
libbpf::bpf_func_id fn;
// Assume that if a kernel has probe_read_kernel it has the other 3 too
if (bpftrace_.feature_->has_helper_probe_read_kernel())
{
if (as == AddrSpace::kernel)
{
fn = str ? libbpf::BPF_FUNC_probe_read_kernel_str
: libbpf::BPF_FUNC_probe_read_kernel;
}
else if (as == AddrSpace::user)
{
fn = str ? libbpf::BPF_FUNC_probe_read_user_str
: libbpf::BPF_FUNC_probe_read_user;
}
else
{
// if the kernel has the new helpers but AS is still none it is a bug
// in bpftrace, assert catches it for debug builds.
// assert(as != AddrSpace::none);
static bool warnonce = false;
if (!warnonce)
{
warnonce = true;
LOG(WARNING) << "Addrspace is not set";
}
fn = str ? libbpf::BPF_FUNC_probe_read_str : libbpf::BPF_FUNC_probe_read;
}
}
else
{
fn = str ? libbpf::BPF_FUNC_probe_read_str : libbpf::BPF_FUNC_probe_read;
}
return fn;
}
AllocaInst *IRBuilderBPF::CreateUSym(llvm::Value *val)
{
std::vector<llvm::Type *> elements = {
getInt64Ty(), // addr
getInt64Ty(), // pid
};
StructType *usym_t = GetStructType("usym_t", elements, false);
AllocaInst *buf = CreateAllocaBPF(usym_t, "usym");
Value *pid = CreateLShr(CreateGetPidTgid(), 32);
// The extra 0 here ensures the type of addr_offset will be int64
Value *addr_offset = CreateGEP(buf, { getInt64(0), getInt32(0) });
Value *pid_offset = CreateGEP(buf, { getInt64(0), getInt32(1) });
CreateStore(val, addr_offset);
CreateStore(pid, pid_offset);
return buf;
}
StructType *IRBuilderBPF::GetStructType(
std::string name,
const std::vector<llvm::Type *> &elements,
bool packed)
{
auto search = structs_.find(name);
if (search != structs_.end())
return search->second;
StructType *s = StructType::create(elements, name, packed);
structs_.insert({ name, s });
return s;
}
IRBuilderBPF::IRBuilderBPF(LLVMContext &context,
Module &module,
BPFtrace &bpftrace)
: IRBuilder<>(context),
module_(module),
bpftrace_(bpftrace)
{
// Declare external LLVM function
FunctionType *pseudo_func_type = FunctionType::get(
getInt64Ty(),
{getInt64Ty(), getInt64Ty()},
false);
Function::Create(
pseudo_func_type,
GlobalValue::ExternalLinkage,
"llvm.bpf.pseudo",
&module_);
}
AllocaInst *IRBuilderBPF::CreateAllocaBPF(llvm::Type *ty, llvm::Value *arraysize, const std::string &name)
{
Function *parent = GetInsertBlock()->getParent();
BasicBlock &entry_block = parent->getEntryBlock();
auto ip = saveIP();
if (entry_block.empty())
SetInsertPoint(&entry_block);
else
SetInsertPoint(&entry_block.front());
AllocaInst *alloca = CreateAlloca(ty, arraysize, name);
restoreIP(ip);
CreateLifetimeStart(alloca);
return alloca;
}
AllocaInst *IRBuilderBPF::CreateAllocaBPF(llvm::Type *ty, const std::string &name)
{
return CreateAllocaBPF(ty, nullptr, name);
}
AllocaInst *IRBuilderBPF::CreateAllocaBPF(const SizedType &stype, const std::string &name)
{
llvm::Type *ty = GetType(stype);
return CreateAllocaBPF(ty, nullptr, name);
}
AllocaInst *IRBuilderBPF::CreateAllocaBPFInit(const SizedType &stype, const std::string &name)
{
Function *parent = GetInsertBlock()->getParent();
BasicBlock &entry_block = parent->getEntryBlock();
auto ip = saveIP();
if (entry_block.empty())
SetInsertPoint(&entry_block);
else
SetInsertPoint(&entry_block.front());
llvm::Type *ty = GetType(stype);
AllocaInst *alloca = CreateAllocaBPF(ty, nullptr, name);
if (needMemcpy(stype))
{
CREATE_MEMSET(alloca, getInt8(0), stype.size, 1);
}
else
{
CreateStore(getInt64(0), alloca);
}
restoreIP(ip);
CreateLifetimeStart(alloca);
return alloca;
}
AllocaInst *IRBuilderBPF::CreateAllocaBPF(const SizedType &stype, llvm::Value *arraysize, const std::string &name)
{
llvm::Type *ty = GetType(stype);
return CreateAllocaBPF(ty, arraysize, name);
}
AllocaInst *IRBuilderBPF::CreateAllocaBPF(int bytes, const std::string &name)
{
llvm::Type *ty = ArrayType::get(getInt8Ty(), bytes);
return CreateAllocaBPF(ty, name);
}
llvm::ConstantInt *IRBuilderBPF::GetIntSameSize(uint64_t C, llvm::Type *ty)
{
assert(ty->isIntegerTy());
unsigned size = ty->getIntegerBitWidth();
return getIntN(size, C);
}
llvm::ConstantInt *IRBuilderBPF::GetIntSameSize(uint64_t C, llvm::Value *expr)
{
unsigned size = expr->getType()->getIntegerBitWidth();
return getIntN(size, C);
}
llvm::Type *IRBuilderBPF::GetType(const SizedType &stype)
{
llvm::Type *ty;
if (stype.IsArray())
{
ty = ArrayType::get(getInt8Ty(), stype.size);
}
else if (stype.IsTupleTy())
{
std::vector<llvm::Type *> llvm_elems;
std::ostringstream ty_name;
for (const auto &elem : stype.GetFields())
{
auto &elemtype = elem.type;
llvm_elems.emplace_back(GetType(elemtype));
ty_name << elemtype << "_";
}
ty_name << "_tuple_t";
ty = GetStructType(ty_name.str(), llvm_elems, false);
}
else if (stype.IsPtrTy())
{
ty = getInt64Ty();
}
else if (stype.IsRecordTy())
{
ty = ArrayType::get(getInt8Ty(), stype.size);
}
else
{
switch (stype.size)
{
case 16:
ty = getInt128Ty();
break;
case 8:
ty = getInt64Ty();
break;
case 4:
ty = getInt32Ty();
break;
case 2:
ty = getInt16Ty();
break;
case 1:
ty = getInt8Ty();
break;
default:
LOG(FATAL) << stype.size << " is not a valid type size for GetType";
}
}
return ty;
}
CallInst *IRBuilderBPF::createCall(Value *callee,
ArrayRef<Value *> args,
const Twine &Name)
{
#if LLVM_VERSION_MAJOR >= 11
auto *calleePtrType = cast<PointerType>(callee->getType());
auto *calleeType = cast<FunctionType>(calleePtrType->getElementType());
return CreateCall(calleeType, callee, args, Name);
#else
return CreateCall(callee, args, Name);
#endif
}
CallInst *IRBuilderBPF::CreateBpfPseudoCall(int mapfd)
{
Function *pseudo_func = module_.getFunction("llvm.bpf.pseudo");
return createCall(pseudo_func,
{ getInt64(BPF_PSEUDO_MAP_FD), getInt64(mapfd) },
"pseudo");
}
CallInst *IRBuilderBPF::CreateBpfPseudoCall(Map &map)
{
int mapfd = bpftrace_.maps[map.ident].value()->mapfd_;
return CreateBpfPseudoCall(mapfd);
}
CallInst *IRBuilderBPF::createMapLookup(int mapfd, AllocaInst *key)
{
Value *map_ptr = CreateBpfPseudoCall(mapfd);
// void *map_lookup_elem(struct bpf_map * map, void * key)
// Return: Map value or NULL
assert(key->getType()->isPointerTy());
FunctionType *lookup_func_type = FunctionType::get(
getInt8PtrTy(), { map_ptr->getType(), key->getType() }, false);
PointerType *lookup_func_ptr_type = PointerType::get(lookup_func_type, 0);
Constant *lookup_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_map_lookup_elem),
lookup_func_ptr_type);
return createCall(lookup_func, { map_ptr, key }, "lookup_elem");
}
CallInst *IRBuilderBPF::CreateGetJoinMap(Value *ctx, const location &loc)
{
AllocaInst *key = CreateAllocaBPF(getInt32Ty(), "key");
CreateStore(getInt32(0), key);
CallInst *call = createMapLookup(
bpftrace_.maps[MapManager::Type::Join].value()->mapfd_, key);
CreateHelperErrorCond(ctx, call, libbpf::BPF_FUNC_map_lookup_elem, loc, true);
return call;
}
Value *IRBuilderBPF::CreateMapLookupElem(Value *ctx,
Map &map,
AllocaInst *key,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
int mapfd = bpftrace_.maps[map.ident].value()->mapfd_;
return CreateMapLookupElem(ctx, mapfd, key, map.type, loc);
}
Value *IRBuilderBPF::CreateMapLookupElem(Value *ctx,
int mapfd,
AllocaInst *key,
SizedType &type,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
CallInst *call = createMapLookup(mapfd, key);
// Check if result == 0
Function *parent = GetInsertBlock()->getParent();
BasicBlock *lookup_success_block = BasicBlock::Create(module_.getContext(), "lookup_success", parent);
BasicBlock *lookup_failure_block = BasicBlock::Create(module_.getContext(), "lookup_failure", parent);
BasicBlock *lookup_merge_block = BasicBlock::Create(module_.getContext(), "lookup_merge", parent);
AllocaInst *value = CreateAllocaBPF(type, "lookup_elem_val");
Value *condition = CreateICmpNE(
CreateIntCast(call, getInt8PtrTy(), true),
ConstantExpr::getCast(Instruction::IntToPtr, getInt64(0), getInt8PtrTy()),
"map_lookup_cond");
CreateCondBr(condition, lookup_success_block, lookup_failure_block);
SetInsertPoint(lookup_success_block);
if (needMemcpy(type))
CREATE_MEMCPY(value, call, type.size, 1);
else
{
assert(value->getType()->isPointerTy() &&
(value->getType()->getElementType() == getInt64Ty()));
// createMapLookup returns an u8*
auto *cast = CreatePointerCast(call, value->getType(), "cast");
CreateStore(CreateLoad(getInt64Ty(), cast), value);
}
CreateBr(lookup_merge_block);
SetInsertPoint(lookup_failure_block);
if (needMemcpy(type))
CREATE_MEMSET(value, getInt8(0), type.size, 1);
else
CreateStore(getInt64(0), value);
CreateHelperError(ctx, getInt32(0), libbpf::BPF_FUNC_map_lookup_elem, loc);
CreateBr(lookup_merge_block);
SetInsertPoint(lookup_merge_block);
if (needMemcpy(type))
return value;
Value *ret = CreateLoad(value);
CreateLifetimeEnd(value);
return ret;
}
void IRBuilderBPF::CreateMapUpdateElem(Value *ctx,
Map &map,
AllocaInst *key,
Value *val,
const location &loc)
{
Value *map_ptr = CreateBpfPseudoCall(map);
assert(ctx && ctx->getType() == getInt8PtrTy());
assert(key->getType()->isPointerTy());
assert(val->getType()->isPointerTy());
Value *flags = getInt64(0);
// int map_update_elem(struct bpf_map * map, void *key, void * value, u64
// flags) Return: 0 on success or negative error
FunctionType *update_func_type = FunctionType::get(
getInt64Ty(),
{ map_ptr->getType(), key->getType(), val->getType(), getInt64Ty() },
false);
PointerType *update_func_ptr_type = PointerType::get(update_func_type, 0);
Constant *update_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_map_update_elem),
update_func_ptr_type);
CallInst *call = createCall(update_func,
{ map_ptr, key, val, flags },
"update_elem");
CreateHelperErrorCond(ctx, call, libbpf::BPF_FUNC_map_update_elem, loc);
}
void IRBuilderBPF::CreateMapDeleteElem(Value *ctx,
Map &map,
AllocaInst *key,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
assert(key->getType()->isPointerTy());
Value *map_ptr = CreateBpfPseudoCall(map);
// int map_delete_elem(&map, &key)
// Return: 0 on success or negative error
FunctionType *delete_func_type = FunctionType::get(
getInt64Ty(), { map_ptr->getType(), key->getType() }, false);
PointerType *delete_func_ptr_type = PointerType::get(delete_func_type, 0);
Constant *delete_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_map_delete_elem),
delete_func_ptr_type);
CallInst *call = createCall(delete_func, { map_ptr, key }, "delete_elem");
CreateHelperErrorCond(ctx, call, libbpf::BPF_FUNC_map_delete_elem, loc);
}
void IRBuilderBPF::CreateProbeRead(Value *ctx,
AllocaInst *dst,
size_t size,
Value *src,
AddrSpace as,
const location &loc)
{
return CreateProbeRead(ctx, dst, getInt32(size), src, as, loc);
}
void IRBuilderBPF::CreateProbeRead(Value *ctx,
AllocaInst *dst,
llvm::Value *size,
Value *src,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
assert(size && size->getType()->getIntegerBitWidth() <= 32);
size = CreateIntCast(size, getInt32Ty(), false);
// int bpf_probe_read(void *dst, int size, void *src)
// Return: 0 on success or negative error
auto read_fn = selectProbeReadHelper(as, false);
FunctionType *proberead_func_type = FunctionType::get(
getInt64Ty(), { dst->getType(), getInt32Ty(), src->getType() }, false);
PointerType *proberead_func_ptr_type = PointerType::get(proberead_func_type, 0);
Constant *proberead_func = ConstantExpr::getCast(Instruction::IntToPtr,
getInt64(read_fn),
proberead_func_ptr_type);
CallInst *call = createCall(proberead_func,
{ dst, size, src },
probeReadHelperName(read_fn));
CreateHelperErrorCond(ctx, call, read_fn, loc);
}
Constant *IRBuilderBPF::createProbeReadStrFn(llvm::Type *dst,
llvm::Type *src,
AddrSpace as)
{
assert(src && (src->isIntegerTy() || src->isPointerTy()));
// int bpf_probe_read_str(void *dst, int size, const void *unsafe_ptr)
FunctionType *probereadstr_func_type = FunctionType::get(
getInt64Ty(), { dst, getInt32Ty(), src }, false);
PointerType *probereadstr_func_ptr_type = PointerType::get(
probereadstr_func_type, 0);
return ConstantExpr::getCast(Instruction::IntToPtr,
getInt64(selectProbeReadHelper(as, true)),
probereadstr_func_ptr_type);
}
CallInst *IRBuilderBPF::CreateProbeReadStr(Value *ctx,
AllocaInst *dst,
size_t size,
Value *src,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
return CreateProbeReadStr(ctx, dst, getInt32(size), src, as, loc);
}
CallInst *IRBuilderBPF::CreateProbeReadStr(Value *ctx,
Value *dst,
size_t size,
Value *src,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
Constant *fn = createProbeReadStrFn(dst->getType(), src->getType(), as);
auto read_fn = selectProbeReadHelper(as, true);
CallInst *call = createCall(fn,
{ dst, getInt32(size), src },
probeReadHelperName(read_fn));
CreateHelperErrorCond(ctx, call, read_fn, loc);
return call;
}
CallInst *IRBuilderBPF::CreateProbeReadStr(Value *ctx,
AllocaInst *dst,
llvm::Value *size,
Value *src,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
assert(dst && dst->getAllocatedType()->isArrayTy() &&
dst->getAllocatedType()->getArrayElementType() == getInt8Ty());
assert(size && size->getType()->isIntegerTy());
auto *size_i32 = CreateIntCast(size, getInt32Ty(), false);
Constant *fn = createProbeReadStrFn(dst->getType(), src->getType(), as);
auto read_fn = selectProbeReadHelper(as, true);
CallInst *call = createCall(fn,
{ dst, size_i32, src },
probeReadHelperName(read_fn));
CreateHelperErrorCond(ctx, call, read_fn, loc);
return call;
}
Value *IRBuilderBPF::CreateUSDTReadArgument(Value *ctx,
struct bcc_usdt_argument *argument,
Builtin &builtin,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
// TODO (mmarchini): Handle base + index * scale addressing.
// https://github.com/iovisor/bcc/pull/988
if (argument->valid & BCC_USDT_ARGUMENT_INDEX_REGISTER_NAME)
LOG(ERROR) << "index register is not handled yet ["
<< argument->index_register_name << "]";
if (argument->valid & BCC_USDT_ARGUMENT_SCALE)
LOG(ERROR) << "scale is not handled yet [" << argument->scale << "]";
if (argument->valid & BCC_USDT_ARGUMENT_DEREF_IDENT)
LOG(ERROR) << "defer ident is not handled yet [" << argument->deref_ident
<< "]";
if (argument->valid & BCC_USDT_ARGUMENT_CONSTANT)
return getInt64(argument->constant);
Value *result = nullptr;
if (argument->valid & BCC_USDT_ARGUMENT_BASE_REGISTER_NAME) {
int offset = 0;
offset = arch::offset(argument->base_register_name);
if (offset < 0)
{
LOG(FATAL) << "offset for register " << argument->base_register_name
<< " not known";
}
// Argument size must be 1, 2, 4, or 8. See
// https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
int abs_size = std::abs(argument->size);
assert(abs_size == 1 || abs_size == 2 || abs_size == 4 || abs_size == 8);
// bpftrace's args are internally represented as 64 bit integers. However,
// the underlying argument (of the target program) may be less than 64
// bits. So we must be careful to zero out unused bits.
Value* reg = CreateGEP(ctx, getInt64(offset * sizeof(uintptr_t)), "load_register");
AllocaInst *dst = CreateAllocaBPF(builtin.type, builtin.ident);
if (argument->valid & BCC_USDT_ARGUMENT_DEREF_OFFSET) {
Value *ptr = CreateAdd(CreateLoad(getInt64Ty(), reg),
getInt64(argument->deref_offset));
// Zero out `dst` here in case we read less than 64 bits
CreateStore(getInt64(0), dst);
CreateProbeRead(ctx, dst, abs_size, ptr, as, loc);
result = CreateLoad(dst);
}
else
{
result = CreateLoad(GetType(CreateInt(abs_size * 8)), reg);
result = CreateIntCast(result, getInt64Ty(), argument->size < 0);
}
CreateLifetimeEnd(dst);
}
return result;
}
Value *IRBuilderBPF::CreateUSDTReadArgument(Value *ctx,
AttachPoint *attach_point,
int usdt_location_index,
int arg_num,
Builtin &builtin,
pid_t pid,
AddrSpace as,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
struct bcc_usdt_argument argument;
void *usdt;
if (pid) {
//FIXME use attach_point->target when iovisor/bcc#2064 is merged
usdt = bcc_usdt_new_frompid(pid, nullptr);
} else {
usdt = bcc_usdt_new_frompath(attach_point->target.c_str());
}
if (usdt == nullptr) {
LOG(ERROR) << "failed to initialize usdt context for probe "
<< attach_point->target;
exit(-1);
}
std::string ns = attach_point->usdt.provider;
std::string func = attach_point->usdt.name;
if (bcc_usdt_get_argument(usdt,
ns.c_str(),
func.c_str(),
usdt_location_index,
arg_num,
&argument) != 0)
{
LOG(ERROR) << "couldn't get argument " << arg_num << " for "
<< attach_point->target << ":" << attach_point->ns << ":"
<< attach_point->func;
exit(-2);
}
Value *result = CreateUSDTReadArgument(ctx, &argument, builtin, as, loc);
bcc_usdt_close(usdt);
return result;
}
Value *IRBuilderBPF::CreateStrcmp(Value *ctx,
Value *val,
AddrSpace as,
std::string str,
const location &loc,
bool inverse)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
auto cmpAmount = strlen(str.c_str()) + 1;
return CreateStrncmp(ctx, val, as, str, cmpAmount, loc, inverse);
}
Value *IRBuilderBPF::CreateStrncmp(Value *ctx __attribute__((unused)),
Value *val,
AddrSpace as __attribute__((unused)),
std::string str,
uint64_t n,
const location &loc __attribute__((unused)),
bool inverse)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
PointerType *valp = cast<PointerType>(val->getType());
#ifndef NDEBUG
assert(valp->getElementType()->isArrayTy() &&
valp->getElementType()->getArrayElementType() == getInt8Ty());
#endif
Function *parent = GetInsertBlock()->getParent();
BasicBlock *str_ne = BasicBlock::Create(module_.getContext(), "strcmp.false", parent);
AllocaInst *store = CreateAllocaBPF(getInt1Ty(), "strcmp.result");
CreateStore(getInt1(!inverse), store);
// If the size of array is smaller than n, the condition is always false
if (valp->getElementType()->getArrayNumElements() >= n)
{
const char *c_str = str.c_str();
for (size_t i = 0; i < n; i++)
{
BasicBlock *char_eq = BasicBlock::Create(module_.getContext(),
"strcmp.loop",
parent);
auto *ptr = CreateGEP(val, { getInt32(0), getInt32(i) });
Value *l = CreateLoad(getInt8Ty(), ptr);
Value *r = getInt8(c_str[i]);
Value *cmp = CreateICmpNE(l, r, "strcmp.cmp");
CreateCondBr(cmp, str_ne, char_eq);
SetInsertPoint(char_eq);
}
}
CreateStore(getInt1(inverse), store);
CreateBr(str_ne);
SetInsertPoint(str_ne);
Value *result = CreateLoad(store);
CreateLifetimeEnd(store);
result = CreateIntCast(result, getInt64Ty(), false);
return result;
}
Value *IRBuilderBPF::CreateStrcmp(Value *ctx,
Value *val1,
AddrSpace as1,
Value *val2,
AddrSpace as2,
const location &loc,
bool inverse)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
return CreateStrncmp(
ctx, val1, as1, val2, as2, bpftrace_.strlen_, loc, inverse);
}
Value *IRBuilderBPF::CreateStrncmp(Value *ctx,
Value *val1,
AddrSpace as1,
Value *val2,
AddrSpace as2,
uint64_t n,
const location &loc,
bool inverse)
{
/*
// This function compares each character of the two string.
// It returns true if all are equal and false if any are different
// strcmp(String val1, String val2)
{
for (size_t i = 0; i < n; i++)
{
if (val1[i] != val2[i])
{
return false;
}
if (val1[i] == NULL)
{
return true;
}
}
return true;
}
*/
#ifndef NDEBUG
PointerType *val1p = cast<PointerType>(val1->getType());
PointerType *val2p = cast<PointerType>(val2->getType());
assert(val1p->getElementType()->isArrayTy() &&
val1p->getElementType()->getArrayElementType() == getInt8Ty());
assert(val2p->getElementType()->isArrayTy() &&
val2p->getElementType()->getArrayElementType() == getInt8Ty());
#endif
Function *parent = GetInsertBlock()->getParent();
AllocaInst *store = CreateAllocaBPF(getInt1Ty(), "strcmp.result");
BasicBlock *str_ne = BasicBlock::Create(module_.getContext(),
"strcmp.false",
parent);
BasicBlock *done = BasicBlock::Create(module_.getContext(),
"strcmp.done",
parent);
CreateStore(getInt1(!inverse), store);
Value *null_byte = getInt8(0);
AllocaInst *val_l = CreateAllocaBPF(getInt8Ty(), "strcmp.char_l");
AllocaInst *val_r = CreateAllocaBPF(getInt8Ty(), "strcmp.char_r");
for (size_t i = 0; i < n; i++)
{
BasicBlock *char_eq = BasicBlock::Create(module_.getContext(),
"strcmp.loop",
parent);
BasicBlock *loop_null_check = BasicBlock::Create(module_.getContext(),
"strcmp.loop_null_cmp",
parent);
auto *ptr1 = CreateGEP(val1, { getInt32(0), getInt32(i) });
CreateProbeRead(ctx, val_l, 1, ptr1, as1, loc);
Value *l = CreateLoad(getInt8Ty(), val_l);
auto *ptr2 = CreateGEP(val2, { getInt32(0), getInt32(i) });
CreateProbeRead(ctx, val_r, 1, ptr2, as2, loc);
Value *r = CreateLoad(getInt8Ty(), val_r);
Value *cmp = CreateICmpNE(l, r, "strcmp.cmp");
CreateCondBr(cmp, str_ne, loop_null_check);
SetInsertPoint(loop_null_check);
Value *cmp_null = CreateICmpEQ(l, null_byte, "strcmp.cmp_null");
CreateCondBr(cmp_null, done, char_eq);
SetInsertPoint(char_eq);
}
CreateBr(done);
SetInsertPoint(done);
CreateStore(getInt1(inverse), store);
CreateBr(str_ne);
SetInsertPoint(str_ne);
Value *result = CreateLoad(store);
CreateLifetimeEnd(store);
CreateLifetimeEnd(val_l);
CreateLifetimeEnd(val_r);
result = CreateIntCast(result, getInt64Ty(), false);
return result;
}
CallInst *IRBuilderBPF::CreateGetNs(bool boot_time)
{
// u64 ktime_get_ns()
// Return: current ktime
auto fn = boot_time ? libbpf::BPF_FUNC_ktime_get_boot_ns
: libbpf::BPF_FUNC_ktime_get_ns;
FunctionType *gettime_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *gettime_func_ptr_type = PointerType::get(gettime_func_type, 0);
Constant *gettime_func = ConstantExpr::getCast(Instruction::IntToPtr,
getInt64(fn),
gettime_func_ptr_type);
return createCall(gettime_func, {}, "get_ns");
}
CallInst *IRBuilderBPF::CreateGetPidTgid()
{
// u64 bpf_get_current_pid_tgid(void)
// Return: current->tgid << 32 | current->pid
FunctionType *getpidtgid_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getpidtgid_func_ptr_type = PointerType::get(getpidtgid_func_type, 0);
Constant *getpidtgid_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_current_pid_tgid),
getpidtgid_func_ptr_type);
return createCall(getpidtgid_func, {}, "get_pid_tgid");
}
CallInst *IRBuilderBPF::CreateGetCurrentCgroupId()
{
// u64 bpf_get_current_cgroup_id(void)
// Return: 64-bit cgroup-v2 id
FunctionType *getcgroupid_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getcgroupid_func_ptr_type = PointerType::get(
getcgroupid_func_type, 0);
Constant *getcgroupid_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_current_cgroup_id),
getcgroupid_func_ptr_type);
return createCall(getcgroupid_func, {}, "get_cgroup_id");
}
CallInst *IRBuilderBPF::CreateGetUidGid()
{
// u64 bpf_get_current_uid_gid(void)
// Return: current_gid << 32 | current_uid
FunctionType *getuidgid_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getuidgid_func_ptr_type = PointerType::get(getuidgid_func_type, 0);
Constant *getuidgid_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_current_uid_gid),
getuidgid_func_ptr_type);
return createCall(getuidgid_func, {}, "get_uid_gid");
}
CallInst *IRBuilderBPF::CreateGetCpuId()
{
// u32 bpf_raw_smp_processor_id(void)
// Return: SMP processor ID
FunctionType *getcpuid_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getcpuid_func_ptr_type = PointerType::get(getcpuid_func_type, 0);
Constant *getcpuid_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_smp_processor_id),
getcpuid_func_ptr_type);
return createCall(getcpuid_func, {}, "get_cpu_id");
}
CallInst *IRBuilderBPF::CreateGetCurrentTask()
{
// u64 bpf_get_current_task(void)
// Return: current task_struct
FunctionType *getcurtask_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getcurtask_func_ptr_type = PointerType::get(getcurtask_func_type, 0);
Constant *getcurtask_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_current_task),
getcurtask_func_ptr_type);
return createCall(getcurtask_func, {}, "get_cur_task");
}
CallInst *IRBuilderBPF::CreateGetRandom()
{
// u64 bpf_get_prandom_u32(void)
// Return: random
FunctionType *getrandom_func_type = FunctionType::get(getInt64Ty(), false);
PointerType *getrandom_func_ptr_type = PointerType::get(getrandom_func_type, 0);
Constant *getrandom_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_prandom_u32),
getrandom_func_ptr_type);
return createCall(getrandom_func, {}, "get_random");
}
CallInst *IRBuilderBPF::CreateGetStackId(Value *ctx,
bool ustack,
StackType stack_type,
const location &loc)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
Value *map_ptr = CreateBpfPseudoCall(
bpftrace_.maps[stack_type].value()->mapfd_);
int flags = 0;
if (ustack)
flags |= (1<<8);
Value *flags_val = getInt64(flags);
// int bpf_get_stackid(struct pt_regs *ctx, struct bpf_map *map, u64 flags)
// Return: >= 0 stackid on success or negative error
FunctionType *getstackid_func_type = FunctionType::get(
getInt64Ty(),
{ getInt8PtrTy(), map_ptr->getType(), getInt64Ty() },
false);
PointerType *getstackid_func_ptr_type = PointerType::get(getstackid_func_type, 0);
Constant *getstackid_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_stackid),
getstackid_func_ptr_type);
CallInst *call = createCall(getstackid_func,
{ ctx, map_ptr, flags_val },
"get_stackid");
CreateHelperErrorCond(ctx, call, libbpf::BPF_FUNC_get_stackid, loc);
return call;
}
void IRBuilderBPF::CreateGetCurrentComm(Value *ctx,
AllocaInst *buf,
size_t size,
const location &loc)
{
assert(buf->getType()->getElementType()->isArrayTy() &&
buf->getType()->getElementType()->getArrayNumElements() >= size &&
buf->getType()->getElementType()->getArrayElementType() ==
getInt8Ty());
// int bpf_get_current_comm(char *buf, int size_of_buf)
// Return: 0 on success or negative error
FunctionType *getcomm_func_type = FunctionType::get(
getInt64Ty(), { buf->getType(), getInt64Ty() }, false);
PointerType *getcomm_func_ptr_type = PointerType::get(getcomm_func_type, 0);
Constant *getcomm_func = ConstantExpr::getCast(
Instruction::IntToPtr,
getInt64(libbpf::BPF_FUNC_get_current_comm),
getcomm_func_ptr_type);
CallInst *call = createCall(getcomm_func,
{ buf, getInt64(size) },
"get_comm");
CreateHelperErrorCond(ctx, call, libbpf::BPF_FUNC_get_current_comm, loc);
}
void IRBuilderBPF::CreatePerfEventOutput(Value *ctx, Value *data, size_t size)
{
assert(ctx && ctx->getType() == getInt8PtrTy());
assert(data && data->getType()->isPointerTy());
Value *map_ptr = CreateBpfPseudoCall(
bpftrace_.maps[MapManager::Type::PerfEvent].value()->mapfd_);
Value *flags_val = CreateGetCpuId();
Value *size_val = getInt64(size);
// int bpf_perf_event_output(struct pt_regs *ctx, struct bpf_map *map,
// u64 flags, void *data, u64 size)
FunctionType *perfoutput_func_type = FunctionType::get(getInt64Ty(),