commit 5bb82b0d0d6e7769bfbddeac3b7ad89728d9f856
parent 5eed6f031fb5521acbcbb4cc6e774bde5e646292
Author: dwrz <dwrz@dwrz.net>
Date: Fri, 13 Nov 2020 17:14:44 +0000
Update x86 assembly slides
Diffstat:
1 file changed, 26 insertions(+), 16 deletions(-)
diff --git a/x86-assembly/slides.org b/x86-assembly/slides.org
@@ -8,7 +8,7 @@ Slides and code: https://github.com/dwrz/talks/x86-assembly.
* 2. Overview
-1. Follow a trail of questions... into the depths of the machine.
+1. Follow a trail of questions into the depths of the machine.
2. Peel away some abstractions on the way.
3. Gloss over a bunch of stuff (we have an hour, not a semester).
4. Surface (hopefully) with a better understanding of how computers work.
@@ -40,11 +40,11 @@ Does it do /anything/?
We can tell, because it takes a few milliseconds to execute.
#+begin_src bash :results raw
-time node -e "console.log('Hello, World');"
+time node -e ""
#+end_src
#+begin_src bash :results raw
-time node -e ""
+time node -e "console.log('Hello, World');"
#+end_src
* 7. It /definitely/ does /something/.
@@ -224,18 +224,34 @@ strace ./exit
- Hardware specific: e.g., x86 Assembly differs from ARM Assembly.
- Often OS specific --> Linux System Calls != BSD, Mac, Windows system calls.
- Different syntax formats: ATT, Intel.
+ - Examples use ATT syntax.
- What instructions? Need to consult hardware manual.
- [[https://software.intel.com/content/www/us/en/develop/articles/intel-sdm.html][Intel x86 Developer Manual]] is ~5,000 pages long, plus errata.
+#+begin_src bash
+lscpu
+#+end_src
+
* 21. Use Cases
- Low-level programming (micro-controllers, operating systems)
- Resource Constrained Hardware
- - [[https://github.com/chrislgarry/Apollo-11][Apollo 11 Guidance Computer Assembly]]
- - [[https://github.com/pret/pokered][Pokemon Red/Blue Assembly]]
+ - [[https://github.com/chrislgarry/Apollo-11][Apollo 11 Guidance Computer Assembly]] (1969)
+ - [[https://github.com/pret/pokered][Pokemon Red/Blue Assembly]] (1996, AA batteries)
- Performance
+ - Less runtime overhead (system calls, etc)
+ - Better code than compiler (harder to do these days)
- Control
+ - Instructions not available in higher level language
- Reverse Engineering
+#+begin_src bash
+hexdump -C exit
+#+end_src
+
+#+begin_src bash
+objdump -D exit
+#+end_src
+
* 22. Instructions
- Represented by numbers (opcodes).
- Describe an operation the CPU should perform, e.g.:
@@ -251,14 +267,6 @@ strace ./exit
- *Executes* the instruction.
- Increments the instruction pointer.
-#+begin_src bash
-hexdump -C exit
-#+end_src
-
-#+begin_src bash
-objdump -D exit
-#+end_src
-
* 24. Registers
- Storage on the CPU (fastest storage).
- Act as a scratchpad -- temporary variables.
@@ -307,7 +315,7 @@ Programs are either sequential, looping, or branching.
- CPU sets FLAGS register after instruction: e.g., result is zero, negative.
- Jump to code based on the state of FLAGS.
-- Jump changes RIP (instruction pointer).
+- Jump changes instruction pointer.
[[file:src/control-flow/control-flow.s]]
@@ -343,6 +351,8 @@ Which side of the street should we drive on?
Either way works, both are used in practice.
What matters is agreement on an approach.
+[[file:static/convention.jpg]]
+
System V AMD64 ABI is calling convention for Unix x64 systems:
- Some registers must be saved by the caller, so callee can use them.
- Some registers must be saved by callee, if the plan to use them later.
@@ -385,14 +395,14 @@ node -e ""
- Tradeoffs
* 35. Conclusion
-- Appreciation for higher level, and work done to get us here.
- Insight into how computers work.
+- Appreciation for higher level, and work done to get us here.
- A platform to better understand things like functions, closures, APIs, pass by reference and pass by value, performance.
* 36. References / Further Reading
+- [[https://www.youtube.com/watch?v=tpIctyqH29Q&list=PL8dPuuaLjXtNlUrzyH5r6jN9ulIgZBpdo][Crash Course: Computer Science]]
- Davy Wybiral, [[https://www.youtube.com/playlist?list=PLmxT2pVYo5LB5EzTPZGfFN0c2GDiSXgQe][Intro to x86 Assembly Language]]
- Jennifer Rexford, [[https://www.cs.princeton.edu/courses/archive/fall05/cos217/][Princeton COS 217: Introduction to Programming Systems]]
- [[https://en.wikipedia.org/wiki/Structured_program_theorem][Structured Program Theorem]]
- [[https://www.gnu.org/software/gdb/][GDB]]
-- [[https://www.youtube.com/watch?v=tpIctyqH29Q&list=PL8dPuuaLjXtNlUrzyH5r6jN9ulIgZBpdo][Crash Course: Computer Science]]
