3rd-party/linux-kernel-module-cheat
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readme: double spaces!!!

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Ciro Santilli 六四事件 法轮功
2019-11-15 00:00:00 +00:00
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README.adoc
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@@ -1,5 +1,5 @@
= Linux Kernel Module Cheat
:description: The perfect emulation setup to study and develop the <<linux-kernel>> v5.2.1, kernel modules, <<qemu-buildroot-setup,QEMU>>, <<gem5-buildroot-setup,gem5>> and x86_64, ARMv7 and ARMv8 <<userland-assembly,userland>> and <<baremetal-setup,baremetal>> assembly, <<c,ANSI C>>, <<cpp,C++>> and <<posix,POSIX>>. <<gdb>> and <<kgdb>> just work. Powered by <<about-the-qemu-buildroot-setup,Buildroot>> and <<about-the-baremetal-setup,crosstool-NG>>. Highly automated. Thoroughly documented. Automated <<test-this-repo,tests>>. "Tested" in an Ubuntu 18.04 host.
:description: The perfect emulation setup to study and develop the <<linux-kernel>> v5.2.1, kernel modules, <<qemu-buildroot-setup,QEMU>>, <<gem5-buildroot-setup,gem5>> and x86_64, ARMv7 and ARMv8 <<userland-assembly,userland>> and <<baremetal-setup,baremetal>> assembly, <<c,ANSI C>>, <<cpp,C++>> and <<posix,POSIX>>. <<gdb>> and <<kgdb>> just work. Powered by <<about-the-qemu-buildroot-setup,Buildroot>> and <<about-the-baremetal-setup,crosstool-NG>>. Highly automated. Thoroughly documented. Automated <<test-this-repo,tests>>. "Tested" in an Ubuntu 18.04 host.
:idprefix:
:idseparator: -
:nofooter:
@@ -1254,7 +1254,7 @@ For example, to run link:baremetal/arch/aarch64/dump_regs.c[] in QEMU do:
And the terminal prints the values of certain system registers. This example prints registers that are only accessible from <<arm-exception-levels,EL1>> or higher, and thus could not be run in userland.
In addition to the examples under link:baremetal/[], several of the <<userland-content,userland examples>> can also be run in baremetal! This is largely due to the <<about-the-baremetal-setup,awesomeness of Newlib>>.
In addition to the examples under link:baremetal/[], several of the <<userland-content,userland examples>> can also be run in baremetal! This is largely due to the <<about-the-baremetal-setup,awesomeness of Newlib>>.
The examples that work include most <<c,C examples>> that don't rely on complicated syscalls such as threads, and almost all the <<userland-assembly>> examples.
@@ -3765,7 +3765,7 @@ or:
....
./run \
--arch aarch64 \
--userland "$(./getvar --arch aarch64 buildroot_target_dir)/bin/sh" \
--userland "$(./getvar --arch aarch64 buildroot_target_dir)/bin/sh" \
--userland-args='-c "uname -a && pwd"' \
;
....
@@ -4041,7 +4041,7 @@ Since gem5 has to implement syscalls itself in syscall emulation mode, it can of
./run \
--emulator gem5 \
--static userland/arch/x86_64/freestanding/linux/hello.S \
--userland \
--userland \
--trace-stdout \
--trace ExecAll,SyscallBase,SyscallVerbose \
;
@@ -5996,7 +5996,7 @@ depends: dep
We can double check with:
....
strings 3 dep2.ko | grep -E 'depends'
strings 3 dep2.ko | grep -E 'depends'
....
The output contains:
@@ -6729,7 +6729,7 @@ Where the data comes from and how to modify it:
In this repo, leaking host information, and to make builds more reproducible, we are setting:
- user and date to dummy values with `KBUILD_BUILD_USER` and `KBUILD_BUILD_TIMESTAMP`
- hostname to the kernel git commit with `KBUILD_BUILD_HOST` and `KBUILD_BUILD_VERSION`
- hostname to the kernel git commit with `KBUILD_BUILD_HOST` and `KBUILD_BUILD_VERSION`
A sample result is:
@@ -9641,7 +9641,7 @@ Buildroot's Linux tools package provides some GPIO CLI tools: `lsgpio`, `gpio-ev
==== LEDs
TODO: broken when `arm` moved to `-M virt`, same as <<gpio>>.
TODO: broken when `arm` moved to `-M virt`, same as <<gpio>>.
Hack QEMU's `hw/misc/arm_sysctl.c` with a printf:
@@ -10714,7 +10714,7 @@ ps Haux | grep qemu | wc
Remember <<qemu-user-mode-does-not-show-stdout-immediately>> though.
At 369a47fc6e5c2f4a7f911c1c058b6088f8824463 + 1 QEMU appears to spawn 3 host threads plus one for every new guest thread created. Remember that link:userland/posix/pthread_count.c[] spawns N + 1 total threads if you count the `main` thread.
At 369a47fc6e5c2f4a7f911c1c058b6088f8824463 + 1 QEMU appears to spawn 3 host threads plus one for every new guest thread created. Remember that link:userland/posix/pthread_count.c[] spawns N + 1 total threads if you count the `main` thread.
====== gem5 syscall emulation multithreading
@@ -11122,7 +11122,7 @@ gnuplot \
xdg-open bst_vs_heap_vs_hashmap.tmp.png
....
The parameters `heap_zoom_max` and `hashmap_zoom_max` are chosen manually interactively to best showcase the regions of interest in those plots.
The parameters `heap_zoom_max` and `hashmap_zoom_max` are chosen manually interactively to best showcase the regions of interest in those plots.
To benchmark on gem5, we first build the benchmark with <<m5ops-instructions>> enabled, and then we run it and extract the stats:
@@ -12219,7 +12219,7 @@ The `--gem5-script biglittle` option enables the alternative `configs/example/ar
Advantages over `fs.py`:
* more representative of mobile ARM SoCs, which almost always have big little cluster
* more representative of mobile ARM SoCs, which almost always have big little cluster
* simpler than `fs.py`, and therefore easier to understand and modify
Disadvantages over `fs.py`:
@@ -15537,7 +15537,7 @@ It competes with <<x86-userland-assembly>> because its implementations are desig
ARM is generally considered a RISC instruction set, although there are some more complex instructions which would not generally be classified as purely RISC.
ARM is developed by the British funded company ARM Holdings: https://en.wikipedia.org/wiki/Arm_Holdings which originated as a joint venture between Acorn Computers, Apple and VLSI Technology in 1990.
ARM is developed by the British funded company ARM Holdings: https://en.wikipedia.org/wiki/Arm_Holdings which originated as a joint venture between Acorn Computers, Apple and VLSI Technology in 1990.
ARM Holdings was bought by the Japanese giant SoftBank in 2016.
@@ -17335,8 +17335,6 @@ IN: main
which does an `eret` and jumps back to 0x4000209c, which is 4 bytes and therefore one instruction after where SVC was taken at 0x40002098.
In QEMU, and then we just continue running from the exception handler address.
On the terminal output, we observe the initial values of:
* DAIF: 0x3c0, i.e. 4 bits (6 to 9) set to 1, which means that exceptions are masked for each exception type: Synchronous, System error, IRQ and FIQ.
@@ -17607,7 +17605,7 @@ TODO: create and study a minimal examples in gem5 where the DMB instruction lead
==== ARM timer
The ARM timer is the simplest way to generate hardware interrupts periodically, and therefore serves as the simples example of <<arm-gic>> usage.
The ARM timer is the simplest way to generate hardware interrupts periodically, and therefore serves as the simples example of <<arm-gic>> usage.
Working on QEMU: link:baremetal/arch/aarch64/timer.c[]
@@ -19448,7 +19446,7 @@ git clone https://my.private.repo.com/my-fork/gem5.git gem5-internal
gem5_internal="$(pwd)/gem5-internal"
....
Next, when you want to build with the private repository, use the `--gem5-build-dir` and `--gem5-source-dir` argument to override our default gem5 source and build locations:
Next, when you want to build with the private repository, use the `--gem5-build-dir` and `--gem5-source-dir` argument to override our default gem5 source and build locations:
....
cd linux-kernel-module-cheat
@@ -20094,7 +20092,7 @@ Go through all the other <<getting-started>> sections in order.
Once everything looks fine, publish the release with:
....
git tag -a v3.0
git tag -a v3.0
# Describe the release int the tag message.
git push --follow-tags
./release-zip --all-archs