github.com/inspektor-gadget/inspektor-gadget@v0.28.1/pkg/operators/ebpf/helpers.go (about)

     1  // Copyright 2024 The Inspektor Gadget authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package ebpfoperator
    16  
    17  import (
    18  	"errors"
    19  	"fmt"
    20  	"os"
    21  	"strings"
    22  	"sync"
    23  
    24  	"github.com/cilium/ebpf"
    25  	"github.com/cilium/ebpf/btf"
    26  )
    27  
    28  type (
    29  	btfTypeValidator func(btf.Type, string) error
    30  	btfPopulateFunc  func(btf.Type, string) error
    31  	prefixFunc       func(string) (string, bool)
    32  	populateEntry    struct {
    33  		prefixFunc   prefixFunc
    34  		validator    btfTypeValidator
    35  		populateFunc btfPopulateFunc
    36  	}
    37  )
    38  
    39  func hasPrefix(prefix string) prefixFunc {
    40  	return func(s string) (string, bool) {
    41  		return strings.TrimPrefix(s, prefix), strings.HasPrefix(s, prefix)
    42  	}
    43  }
    44  
    45  var (
    46  	onceRingbuf      sync.Once
    47  	ringbufAvailable bool
    48  )
    49  
    50  func isRingbufAvailable() bool {
    51  	onceRingbuf.Do(func() {
    52  		ringbuf, err := ebpf.NewMap(&ebpf.MapSpec{
    53  			Type:       ebpf.RingBuf,
    54  			MaxEntries: uint32(os.Getpagesize()),
    55  		})
    56  
    57  		ringbuf.Close()
    58  
    59  		ringbufAvailable = err == nil
    60  	})
    61  
    62  	return ringbufAvailable
    63  }
    64  
    65  func (i *ebpfInstance) validateGlobalConstVoidPtrVar(t btf.Type, varName string) error {
    66  	btfVar, ok := t.(*btf.Var)
    67  	if !ok {
    68  		return errors.New("not of type btf.Var")
    69  	}
    70  
    71  	if btfVar.Linkage != btf.GlobalVar {
    72  		return fmt.Errorf("%q is not a global variable", btfVar.Name)
    73  	}
    74  
    75  	btfPtr, ok := btfVar.Type.(*btf.Pointer)
    76  	if !ok {
    77  		return fmt.Errorf("%q is not a pointer", btfVar.Name)
    78  	}
    79  
    80  	btfConst, ok := btfPtr.Target.(*btf.Const)
    81  	if !ok {
    82  		return fmt.Errorf("%q is not const", btfVar.Name)
    83  	}
    84  
    85  	_, ok = btfConst.Type.(*btf.Void)
    86  	if !ok {
    87  		return fmt.Errorf("%q is not a const void pointer", btfVar.Name)
    88  	}
    89  
    90  	return nil
    91  }