From: Reinhard Tartler <siretart@tauware.de>
Date: Sat, 23 Aug 2025 18:44:09 -0400
Subject: Revert "internal/linux: use unix.Auxv"
Forwarded: not-needed

This reverts commit 8462e8fdd5f99819b1c6ec4cde32703dc2f7954f.
---
 go.mod                       |  2 +-
 go.sum                       |  4 ++--
 internal/linux/auxv.go       | 21 +++++++++++++--------
 internal/unix/types_linux.go |  4 ----
 internal/unix/types_other.go |  4 ----
 5 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/go.mod b/go.mod
index 439844a..03dc022 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/go-quicktest/qt v1.101.0
 	github.com/google/go-cmp v0.6.0
 	github.com/jsimonetti/rtnetlink/v2 v2.0.1
-	golang.org/x/sys v0.30.0
+	golang.org/x/sys v0.28.0
 )
 
 require (
diff --git a/go.sum b/go.sum
index c154a61..3fe5a63 100644
--- a/go.sum
+++ b/go.sum
@@ -23,5 +23,5 @@ golang.org/x/net v0.33.0 h1:74SYHlV8BIgHIFC/LrYkOGIwL19eTYXQ5wc6TBuO36I=
 golang.org/x/net v0.33.0/go.mod h1:HXLR5J+9DxmrqMwG9qjGCxZ+zKXxBru04zlTvWlWuN4=
 golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
-golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
+golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
diff --git a/internal/linux/auxv.go b/internal/linux/auxv.go
index 10508fd..07d5efe 100644
--- a/internal/linux/auxv.go
+++ b/internal/linux/auxv.go
@@ -1,11 +1,12 @@
 package linux
 
 import (
+	"errors"
 	"fmt"
 	"io"
+	_ "unsafe"
 
 	"github.com/cilium/ebpf/internal"
-	"github.com/cilium/ebpf/internal/unix"
 )
 
 type auxvPairReader interface {
@@ -19,8 +20,11 @@ const (
 	_AT_SYSINFO_EHDR = 33 // Offset to vDSO blob in process image
 )
 
+//go:linkname runtime_getAuxv runtime.getAuxv
+func runtime_getAuxv() []uintptr
+
 type auxvRuntimeReader struct {
-	data  [][2]uintptr
+	data  []uintptr
 	index int
 }
 
@@ -36,12 +40,12 @@ func (r *auxvRuntimeReader) ReadAuxvPair() (uint64, uint64, error) {
 	// we manually add the (_AT_NULL, _AT_NULL) pair at the end
 	// that is not provided by the go runtime
 	var tag, value uintptr
-	if r.index < len(r.data) {
-		tag, value = r.data[r.index][0], r.data[r.index][1]
+	if r.index+1 < len(r.data) {
+		tag, value = r.data[r.index], r.data[r.index+1]
 	} else {
 		tag, value = _AT_NULL, _AT_NULL
 	}
-	r.index += 1
+	r.index += 2
 	return uint64(tag), uint64(value), nil
 }
 
@@ -50,9 +54,10 @@ func newAuxvRuntimeReader() (auxvPairReader, error) {
 		return nil, fmt.Errorf("read auxv from runtime: %w", internal.ErrNotSupportedOnOS)
 	}
 
-	data, err := unix.Auxv()
-	if err != nil {
-		return nil, fmt.Errorf("read auxv from runtime: %w", err)
+	data := runtime_getAuxv()
+
+	if len(data)%2 != 0 {
+		return nil, errors.New("malformed auxv passed from runtime")
 	}
 
 	return &auxvRuntimeReader{
diff --git a/internal/unix/types_linux.go b/internal/unix/types_linux.go
index 385adf0..1421add 100644
--- a/internal/unix/types_linux.go
+++ b/internal/unix/types_linux.go
@@ -195,7 +195,3 @@ func SchedSetaffinity(pid int, set *CPUSet) error {
 func SchedGetaffinity(pid int, set *CPUSet) error {
 	return linux.SchedGetaffinity(pid, set)
 }
-
-func Auxv() ([][2]uintptr, error) {
-	return linux.Auxv()
-}
diff --git a/internal/unix/types_other.go b/internal/unix/types_other.go
index 323f7ff..7687373 100644
--- a/internal/unix/types_other.go
+++ b/internal/unix/types_other.go
@@ -278,7 +278,3 @@ func SchedSetaffinity(pid int, set *CPUSet) error {
 func SchedGetaffinity(pid int, set *CPUSet) error {
 	return errNonLinux()
 }
-
-func Auxv() ([][2]uintptr, error) {
-	return nil, errNonLinux()
-}