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https://github.com/dynup/kpatch
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57b51d0bdc
WARN macros are problematic because they embed the line number in an instruction. As a result, when a function is changed higher in a file, the line numbers for any WARN calls below that function in the file can result in unnecessarily changed functions. These macros allow a patch author to hard code the line numbers in WARN macros to prevent functions from otherwise changing and getting pulled into a patch module unnecessarily.
108 lines
3.6 KiB
C
108 lines
3.6 KiB
C
#ifndef __KPATCH_MACROS_H_
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#define __KPATCH_MACROS_H_
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#include <linux/compiler.h>
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#include <linux/bug.h>
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typedef void (*kpatch_loadcall_t)(void);
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typedef void (*kpatch_unloadcall_t)(void);
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struct kpatch_load {
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kpatch_loadcall_t fn;
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char *objname; /* filled in by create-diff-object */
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};
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struct kpatch_unload {
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kpatch_unloadcall_t fn;
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char *objname; /* filled in by create-diff-object */
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};
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/*
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* KPATCH_LOAD_HOOK macro
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*
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* The first line only ensures that the hook being registered has the required
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* function signature. If not, there is compile error on this line.
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*
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* The section line declares a struct kpatch_load to be allocated in a new
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* .kpatch.hook.load section. This kpatch_load_data symbol is later stripped
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* by create-diff-object so that it can be declared in multiple objects that
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* are later linked together, avoiding global symbol collision. Since multiple
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* hooks can be registered, the .kpatch.hook.load section is a table of struct
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* kpatch_load elements that will be executed in series by the kpatch core
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* module at load time, assuming the kernel object (module) is currently
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* loaded; otherwise, the hook is called when module to be patched is loaded
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* via the module load notifier.
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*/
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#define KPATCH_LOAD_HOOK(_fn) \
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static inline kpatch_loadcall_t __loadtest(void) { return _fn; } \
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struct kpatch_load kpatch_load_data __section(.kpatch.hooks.load) = { \
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.fn = _fn, \
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.objname = NULL \
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};
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/*
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* KPATCH_UNLOAD_HOOK macro
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*
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* Same as LOAD hook with s/load/unload/
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*/
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#define KPATCH_UNLOAD_HOOK(_fn) \
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static inline kpatch_unloadcall_t __unloadtest(void) { return _fn; } \
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struct kpatch_unload kpatch_unload_data __section(.kpatch.hooks.unload) = { \
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.fn = _fn, \
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.objname = NULL \
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};
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/*
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* KPATCH_FORCE_UNSAFE macro
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*
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* USE WITH EXTREME CAUTION!
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*
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* Allows patch authors to bypass the activeness safety check at patch
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* load time. Do this ONLY IF 1) the patch application will always/likely
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* fail due to the function being on the stack of at least one thread at
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* all times and 2) it is safe for both the original and patched versions
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* of the function to run concurrently.
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*/
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#define KPATCH_FORCE_UNSAFE(_fn) \
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void *__kpatch_force_func_##_fn __section(.kpatch.force) = _fn;
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/*
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* KPATCH_WARN_*_LINE macros
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*
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* WARN macros are problematic because they embed the line number in an
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* instruction. As a result, when a function is changed higher in a file, the
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* line numbers for any WARN calls below that function in the file can result
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* in unnecessarily changed functions.
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*
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* These macros allow a patch author to hard code the line numbers in WARN
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* macros to prevent functions from otherwise changing and getting pulled into
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* a patch module unnecessarily.
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*
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* TODO: consider moving these __WARN_*_line variants upstream to bug.h
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*/
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#ifndef __WARN_TAINT
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#define __WARN_line(line) warn_slowpath_null(__FILE__, line)
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#define __WARN_printf_line(line, arg...) warn_slowpath_fmt(__FILE__, line, arg)
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#define __WARN_printf_taint_line(line, taint, arg...) \
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warn_slowpath_fmt_taint(__FILE__, line, taint, arg)
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#else
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#error __WARN_TAINT not yet supported
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#endif
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#define KPATCH_WARN_LINE(line, condition, format...) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_printf_line(line, format); \
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unlikely(__ret_warn_on); \
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})
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#define KPATCH_WARN_ON_LINE(line, condition) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_line(line); \
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unlikely(__ret_warn_on); \
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})
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#define KPATCH_WARN_ON_SMP_LINE(line, condition) \
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KPATCH_WARN_ON_LINE(line, condition)
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#endif /* __KPATCH_MACROS_H_ */
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