geno genonullfree

Understanding the Memory Layout of Linux Executables

Required tools for playing around with memory:

hexdump
objdump
readelf
xxd
gcore

ELF

ELF Header

The first portion of any ELF file is the ELF header. This generally provides offsets to other headers (program headers and section headers) within an ELF.

typedef struct {
  unsigned char e_ident[EI_NIDENT];
 uint16_t e_type;

Overview

This document attempts to call out all the elements and mechanisms involved in the discovery as well as hotplug of PCI devices including

QEMU framework
APCI Tables and Methods
Linux Kernel functions and tables

The logic pertaining to the GED interrupt based APCI eventing is specific to NEMU. The rest of this document is generic.

QEMU Hotplug Registration

Flamegraphing in Rust can now be done with a new cargo subcommand. Please check this out before embarking on the legacy journey below: https://github.com/flamegraph-rs/flamegraph

flamegraphing rust binaries' cpu usage with perf

One-time setup

Install perf, using Brendan Gregg's guide: http://www.brendangregg.com/perf.html#Prerequisites
Install flamegraph from repo:

IDAPython cheatsheet

Important links

Basic commands

Get informations on the binary

Regular Colors

Value	Color
\e[0;30m	Black
\e[0;31m	Red
\e[0;32m	Green
\e[0;33m	Yellow
\e[0;34m	Blue
\e[0;35m	Purple

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	/*
	Copyright (c) 2016, Nitin Gode
	All rights reserved.

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions are met:
	* Redistributions of source code must retain the above copyright
	notice, this list of conditions and the following disclaimer.
	* Redistributions in binary form must reproduce the above copyright
	notice, this list of conditions and the following disclaimer in the

	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
	;;;
	;;; Copyright (C), zznop, [email protected]
	;;;
	;;; This software may be modified and distributed under the terms
	;;; of the MIT license. See the LICENSE file for details.
	;;;
	;;; DESCRIPTION
	;;;
	;;; This PoC shellcode is meant to be compiled as a blob and prepended to a ELF