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update patch module terminology

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Try to be more consistent with the terminology.  In various places we
call it a "hotpatch module", "hot patch module", or "patch module".  How
about we just call it a "patch module" everywhere?
This commit is contained in:
Josh Poimboeuf 2014-04-01 16:40:28 -05:00
parent afd3669746
commit a7efb05c81
3 changed files with 34 additions and 34 deletions
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32
README.md
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@ -60,11 +60,11 @@ Make a source patch against the kernel tree:
# from a kernel git tree: # from a kernel git tree:
git diff > /path/to/foo.patch git diff > /path/to/foo.patch
Build the hot patch kernel module: Build the patch module:
kpatch-build /path/to/foo.patch kpatch-build /path/to/foo.patch
This outputs a hot patch module named `kpatch-foo.ko` in the current This outputs a patch module named `kpatch-foo.ko` in the current
directory. Now apply it to the running kernel: directory. Now apply it to the running kernel:
sudo insmod kpatch-foo.ko sudo insmod kpatch-foo.ko
@ -79,29 +79,29 @@ kpatch works at a function granularity: old functions are replaced with new
ones. It has four main components: ones. It has four main components:
- **kpatch-build**: a collection of tools which convert a source diff patch to - **kpatch-build**: a collection of tools which convert a source diff patch to
a hot patch module. They work by compiling the kernel both with and without a patch module. They work by compiling the kernel both with and without
the source patch, comparing the binaries, and generating a hot patch module the source patch, comparing the binaries, and generating a patch module
which includes new binary versions of the functions to be replaced. which includes new binary versions of the functions to be replaced.
- **hot patch module**: a kernel module (.ko file) which includes the - **patch module**: a kernel module (.ko file) which includes the
replacement functions and metadata about the original functions. replacement functions and metadata about the original functions.
- **kpatch core module**: a kernel module (.ko file) which provides an - **kpatch core module**: a kernel module (.ko file) which provides an
interface for the hot patch modules to register new functions for interface for the patch modules to register new functions for
replacement. It uses the kernel ftrace subsystem to hook into the original replacement. It uses the kernel ftrace subsystem to hook into the original
function's mcount call instruction, so that a call to the original function function's mcount call instruction, so that a call to the original function
is redirected to the replacement function. is redirected to the replacement function.
- **kpatch utility:** a command-line tool which allows a user to manage a - **kpatch utility:** a command-line tool which allows a user to manage a
collection of hot patch modules. One or more hot patch modules may be collection of patch modules. One or more patch modules may be
configured to load at boot time, so that a system can remain patched configured to load at boot time, so that a system can remain patched
even after a reboot into the same version of the kernel. even after a reboot into the same version of the kernel.
### kpatch-build ### kpatch-build
The "kpatch-build" command converts a source-level diff patch file to a hot The "kpatch-build" command converts a source-level diff patch file to a kernel
patch kernel module. Most of its work is performed by the kpatch-build script patch module. Most of its work is performed by the kpatch-build script
which uses a collection of utilities: `create-diff-object`, which uses a collection of utilities: `create-diff-object`,
`add-patch-section`, and `link-vmlinux-syms`. `add-patch-section`, and `link-vmlinux-syms`.
@ -120,19 +120,19 @@ The primary steps in kpatch-build are:
sections sections
- Link all the output objects into a cumulative object - Link all the output objects into a cumulative object
- Use `add-patches-section` to add the .patches section that the - Use `add-patches-section` to add the .patches section that the
core kpatch module uses to determine the list of functions that need kpatch core module uses to determine the list of functions that need
to be redirected using ftrace to be redirected using ftrace
- Generate the patch kernel module - Generate the patch module
- Use `link-vmlinux-syms` to hardcode non-exported kernel symbols - Use `link-vmlinux-syms` to hardcode non-exported kernel symbols
into the symbol table of the patch kernel module into the symbol table of the patch module
### Patching ### Patching
The hot patch kernel modules register with the core module (`kpatch.ko`). The patch modules register with the core module (`kpatch.ko`).
They provide information about original functions that need to be replaced, and They provide information about original functions that need to be replaced, and
corresponding function pointers to the replacement functions. corresponding function pointers to the replacement functions.
The kpatch core module registers a trampoline function with ftrace. The The core module registers a trampoline function with ftrace. The
trampoline function is called by ftrace immediately before the original trampoline function is called by ftrace immediately before the original
function begins executing. This occurs with the help of the reserved mcount function begins executing. This occurs with the help of the reserved mcount
call at the beginning of every function, created by the gcc `-mfentry` flag. call at the beginning of every function, created by the gcc `-mfentry` flag.
@ -160,7 +160,7 @@ Limitations
- Patches which modify statically allocated data are not supported. - Patches which modify statically allocated data are not supported.
kpatch-build will detect that and return an error. (In the future kpatch-build will detect that and return an error. (In the future
we will add a facility to support it. It will probably require the we will add a facility to support it. It will probably require the
user to write code which runs at module loading time which manually user to write code which runs at patch module loading time which manually
updates the data.) updates the data.)
- Patches which change the way a function interacts with dynamically - Patches which change the way a function interacts with dynamically
@ -183,7 +183,7 @@ ability to arbitrarily modify the kernel, with or without kpatch.
**Q. How can I detect if somebody has patched the kernel?** **Q. How can I detect if somebody has patched the kernel?**
We hope to create a new kernel TAINT flag which will get set whenever a kpatch We hope to create a new kernel TAINT flag which will get set whenever a patch
module is loaded. module is loaded.
Also, many distros ship with cryptographically signed kernel modules, and will Also, many distros ship with cryptographically signed kernel modules, and will

14
kpatch/kpatch
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@ -31,17 +31,17 @@ usage () {
echo "usage: kpatch <command> [<args>]" >&2 echo "usage: kpatch <command> [<args>]" >&2
echo >&2 echo >&2
echo "Valid commands:" >&2 echo "Valid commands:" >&2
printf ' %-20s %s\n' "install <file>" "install hotpatch module to the kpatch DB" >&2 printf ' %-20s %s\n' "install <file>" "install patch module to the kpatch DB" >&2
printf ' %-20s %s\n' "uninstall <hotpatch>" "uninstall hotpatch module from the kpatch DB" >&2 printf ' %-20s %s\n' "uninstall <patch>" "uninstall patch module from the kpatch DB" >&2
echo >&2 echo >&2
printf ' %-20s %s\n' "load --all" "load all installed hotpatch modules into the running kernel" >&2 printf ' %-20s %s\n' "load --all" "load all installed patch modules into the running kernel" >&2
printf ' %-20s %s\n' "load <hotpatch>" "load installed hotpatch module to the running kernel" >&2 printf ' %-20s %s\n' "load <patch>" "load installed patch module into the running kernel" >&2
printf ' %-20s %s\n' "unload <hotpatch>" "unload hotpatch module from the running kernel" >&2 printf ' %-20s %s\n' "unload <patch>" "unload patch module from the running kernel" >&2
echo >&2 echo >&2
echo >&2 echo >&2
printf ' %-20s %s\n' "info <hotpatch>" "show information about an installed hotpatch module" >&2 printf ' %-20s %s\n' "info <patch>" "show information about an installed patch module" >&2
echo >&2 echo >&2
printf ' %-20s %s\n' "list" "list installed hotpatch modules" >&2 printf ' %-20s %s\n' "list" "list installed patch modules" >&2
exit 1 exit 1
} }

22
man/kpatch.1
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@ -12,25 +12,25 @@ the system.
.SH OPTIONS .SH OPTIONS
install <file> install <file>
install hotpatch module to the kpatch DB install patch module to the kpatch DB
uninstall <hotpatch> uninstall <patch>
uninstall hotpatch module from the kpatch DB uninstall patch module from the kpatch DB
load --all load --all
load all enabled hotpatch modules into the running kernel load all installed patch modules into the running kernel
load <hotpatch> load <patch>
load installed hotpatch module to the running kernel load installed patch module into the running kernel
unload <hotpatch> unload <patch>
unload hotpatch module from the running kernel unload patch module from the running kernel
info <hotpatch> info <patch>
show information about an installed hotpatch module show information about an installed patch module
list list
list installed hotpatch modules list installed patch modules
.SH SEE ALSO .SH SEE ALSO
kpatch-build(1) kpatch-build(1)