From d77576bb523bac542b06621794f26a18efde4fb1 Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Sat, 11 Feb 2023 20:57:40 +0100
Subject: 04: fix load through GOT explanation
---
04_dynld_nostd/README.md | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
(limited to '04_dynld_nostd')
diff --git a/04_dynld_nostd/README.md b/04_dynld_nostd/README.md
index fc5c338..9c284ec 100644
--- a/04_dynld_nostd/README.md
+++ b/04_dynld_nostd/README.md
@@ -638,10 +638,11 @@ Shared libraries on the other hand that also reference the same symbol will go
though a `GOT` entry that is patched by the dynamic linker to point to the
location in the `.bss` section of the main program.
Below this can be seen by the `mov` instruction at address `1024` that the
-relative address `3ff8` is dereferenced to get the value of the `gCalled`
-variable. In the `readelf` dump above it can be seen that there is a relocation
-of type `R_X86_64_GLOB_DAT` for symbol `gCalled` affecting the relative address
-`3ff8` in the shared library.
+relative address `3ff8` is dereferenced, which is the GOT entry for `gCalled`,
+to get the address of `gCalled`. The next instruction at `102b` then loads the
+value of `gCalled` iteself. In the `readelf` dump above it can be seen that
+there is a relocation of type `R_X86_64_GLOB_DAT` for symbol `gCalled`
+affecting the relative address `3ff8` in the shared library.
```bash
> objdump -M intel -d -j .text -j .got libgreet.so
@@ -653,7 +654,7 @@ Disassembly of section .text:
1020: 55 push rbp
1021: 48 89 e5 mov rbp,rsp
1024: 48 8b 05 cd 2f 00 00 mov rax,QWORD PTR [rip+0x2fcd] # 3ff8 <gCalled-0x28>
-
+ 102b: 8b 00 mov eax,DWORD PTR [rax] # load gCalled
...
Disassembly of section .got:
--
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