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Author SHA1 Message Date
Jonathan Herrewijnen
4bbb11908f Merge branch 'main' of https://git.herreweb.nl/EljakimHerrewijnen/Samsung_S7 2024-08-12 16:58:46 +02:00
Jonathan Herrewijnen
de8395b286 updated docs 2024-08-12 16:58:34 +02:00
Jonathan Herrewijnen
19d20965db updated docs 2024-08-12 16:57:40 +02:00
7 changed files with 94 additions and 6 deletions

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@ -19,9 +19,63 @@ As done by Frederic, the bootrom can be dumped using his provided scripts, and c
./exynos-usbdl e payloads/Exynos8890_dump_bootrom.bin dumped_sboot.bin
scripts/split-sboot-8890.sh dumped_sboot.bin
This results in the following files:
.. list-table:: bootrom stages
:header-rows: 1
* - File
- Strings output
- Likely boot stage?
* - sboot.bin.1.bin
- Exynos BL1
- BL1
* - sboot.bin.2.bin
- BL31 %s
- BL31
* - sboot.bin.3.bin
- Unsure. Contains strings like: TOP_DIV_ACLK_MFC_600 and APOLLO_DIV_APOLLO_RUN_MONITOR
- BL2?
* - sboot.bin.4.bin
- Contains more textual information, and references to post BL2 boot, and android information
- Kernel boot/BL33?
debugger
========
Some other information about the debugger and it's current state.
After the initial loading of the debugger, the state reported is:
.. code:: bash
root | DEBUG |
X0 : 0x0 | X1 : 0xffffffff | X2 : 0x20215d8 | X3 : 0x2021894 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
X14 : 0xf | X15 : 0x206d000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x2000 | X20 : 0x2069000 |
X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20219b8 | SP/X31 : 0x2020ef0
With the original bl1
.. code:: bash
root | DEBUG |
X0 : 0x0 | X1 : 0x1 | X2 : 0x20215d8 | X3 : 0x2021894 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
X14 : 0xf | X15 : 0x20c4000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x2000 | X20 : 0x2069000 |
X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20c0000 | SP/X31 : 0x2020ef0
With a modified bl1
.. code:: bash
root | DEBUG |
X0 : 0x0 | X1 : 0x1 | X2 : 0x20215d8 | X3 : 0x2021894 | X4 : 0x4 | X5 : 0x0 | X6 : 0x0 |
X7 : 0x136c0008 | X8 : 0x2069000 | X9 : 0x0 | X10 : 0x2070000 | X11 : 0x0 | X12 : 0x0 | X13 : 0x0 |
X14 : 0xf | X15 : 0x20c4000 | X16 : 0x9 | X17 : 0x0 | X18 : 0x1 | X19 : 0x2000 | X20 : 0x2069000 |
X21 : 0x0 | X22 : 0x0 | X23 : 0x0 | X24 : 0x0 | X25 : 0x0 | X26 : 0x0 | X27 : 0x1 |
X28 : 0x0 | X29 : 0x2020f00 | LR/X30 : 0x20c0000 | SP/X31 : 0x2020ef0
I relocated the debugger to ``0x20c0000`` to prevent overwriting it.
@ -137,6 +191,13 @@ Replacing this function with our debugger makes us jump back:
However this does not fully run bl1, so we will have to dig a bit deeper to see the puropose and when to jump back to the debugger.
Authentication of BL1 seems to be done at ``0x0012848``. With return value '0' expected when this function is executed, to execute other functions.
.. figure:: images/bl1_auth_references.png
:align: center
BL1 authentication.
purpose
-------
bl1 interacts with several pheriperals, from the DTB these are:

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@ -8,10 +8,11 @@ OBJCOPY := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64
LD := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ld.bfd
#==================Target Samsung S7 (8890)==================
CFLAGS_SAMSUNGS7 = -Os
CFLAGS_SAMSUNGS7 = -Os # -Os for optimization for size
dwc3:
$(CC) entry.S -c -o entry.o $(CFLAGS_SAMSUNGS7)
$(CC) $(CFLAGS_SAMSUNGS7) -c test_dwc3.c -o dwc3.o
$(LD) -T test_dwc3.ld entry.o dwc3.o -o dwc3.elf --just-symbols=symbols.txt
$(CC) entry.S -c -o entry.o $(CFLAGS_SAMSUNGS7) # -c compiles assembly code, and -o creates an object file (containing linking and symbol information)
$(CC) $(CFLAGS_SAMSUNGS7) -c test_dwc3.c -o dwc3.o # compiles test_dwc3.c to dwc3.o
$(LD) -T test_dwc3.ld entry.o dwc3.o -o dwc3.elf --just-symbols=symbols.txt # -T for linker script, --just-symbols for symbols file
$(OBJCOPY) -O binary dwc3.elf dwc3.bin

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@ -0,0 +1,17 @@
ifeq ($(ANDROID_NDK_ROOT),)
$(error Error : Set the env variable 'ANDROID_NDK_ROOT' with the path of the Android NDK (version 20))
endif
CC := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android27-clang
AR := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ar
OBJCOPY := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-objcopy
LD := $(ANDROID_NDK_ROOT)/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ld.bfd
#==================Target Samsung S7 (8890)==================
CFLAGS_SAMSUNGS7 = -Os
stage1:
$(CC) entry.S -c -o entry.o $(CFLAGS_SAMSUNGS7)
$(CC) $(CFLAGS_SAMSUNGS7) -c stage1.c -o stage1.o
$(LD) -T linkscript.ld entry.o stage1.o -o stage1.elf --just-symbols=symbols.txt
$(OBJCOPY) -O binary stage1.elf stage1.bin

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@ -0,0 +1,8 @@
# Open a binary file and modify it
bl1 = open('../S7/bl1.bin', 'rb').read()
# Modify the binary file at 1C10
bl1 = bl1[:0x1C1C] + b'\x48' + bl1[0x1C1D:]
# Write the modified binary file
open('../S7/bl1_mod.bin', 'wb').write(bl1)

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@ -15,3 +15,4 @@ stage1:
$(CC) $(CFLAGS_SAMSUNGS7) -c stage1.c -o stage1.o
$(LD) -T linkscript.ld entry.o stage1.o -o stage1.elf --just-symbols=symbols.txt
$(OBJCOPY) -O binary stage1.elf stage1.bin