tetragon

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// SPDX-License-Identifier: Apache-2.0
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// Copyright Authors of Tetragon
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package main
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import (
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	"fmt"
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	"log"
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	"os"
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	"strconv"
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	"strings"
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	"github.com/cilium/tetragon/pkg/ksyms"
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)
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// NB: I should do proper tests but for now, I do something like:
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//
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// $ perf record -g  -e skb:kfree_skb
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// ...
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// $ perf script | tail
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//        ffffffffa870f925 sock_close+0x15 (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa80dfbdc __fput+0xcc (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa80dfdde ____fput+0xe (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa7ec66df task_work_run+0x8f (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa7e04191 exit_to_usermode_loop+0x131 (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa7e045d3 do_syscall_64+0x163 (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//        ffffffffa8a0008c entry_SYSCALL_64+0x7c (/usr/lib/debug/boot/vmlinux-5.4.0-48-generic)
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//            7f78e26f43fb __close+0x3b (/usr/lib/x86_64-linux-gnu/libpthread-2.31.so)
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//            7f78d7217fac [unknown] ([unknown])
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//
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// $ sudo ./ksyms 0xffffffffa870f925
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// addr 0xffffffffa870f925: sock_close()+0x15
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// $  sudo ./ksyms 0xffffffffa8a0008c
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// addr 0xffffffffa8a0008c: entry_SYSCALL_64_after_hwframe()+0x44
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// $ sudo ./ksyms 0xffffffffa7e045d3
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// addr 0xffffffffa7e045d3: do_syscall_64()+0x163
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//
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// ... which I guess is close enough for now...
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func main() {
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	if len(os.Args) < 2 {
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		fmt.Fprintf(os.Stderr, "Usage: %s <addr>\n", os.Args[0])
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		os.Exit(1)
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	}
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	arg := os.Args[1]
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	base := 10
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	if strings.HasPrefix(arg, "0x") {
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		arg = strings.TrimPrefix(arg, "0x")
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		base = 16
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	}
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	addr, err := strconv.ParseUint(arg, base, 64)
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	if err != nil {
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		fmt.Fprintf(os.Stderr, "error parsing address (base: %d) %s", base, err)
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		os.Exit(1)
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	}
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	ks, err := ksyms.NewKsyms("/proc")
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	if err != nil {
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		log.Fatal(err)
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	}
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	fnsym, err := ks.GetFnOffset(addr)
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	if err == nil {
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		fmt.Printf("addr 0x%x: %s\n", addr, fnsym.ToString())
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	} else {
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		fmt.Printf("addr 0x%x: error: %s\n", addr, err)
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	}
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}
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