mirror of
https://github.com/dynup/kpatch
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113 lines
3.8 KiB
C
113 lines
3.8 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/jiffies.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_IGNORE_SECTION macro
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*
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* This macro is for ignoring sections that may change as a side effect of
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* another change or might be a non-bundlable section; that is one that does
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* not honor -ffunction-section and create a one-to-one relation from function
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* symbol to section.
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*/
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#define KPATCH_IGNORE_SECTION(_sec) \
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char *__UNIQUE_ID(kpatch_ignore_section_) __section(.kpatch.ignore.sections) = _sec;
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/*
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* KPATCH_IGNORE_FUNCTION macro
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*
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* This macro is for ignoring functions that may change as a side effect of a
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* change in another function. The WARN class of macros, for example, embed
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* the line number in an instruction, which will cause the function to be
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* detected as changed when, in fact, there has been no functional change.
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*/
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#define KPATCH_IGNORE_FUNCTION(_fn) \
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void *__kpatch_ignore_func_##_fn __section(.kpatch.ignore.functions) = _fn;
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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 load
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* time. Do this ONLY IF 1) the patch application will always/likely fail due
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* to the function being on the stack of at least one thread at all times and
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* 2) it is safe for both the original and patched versions of the function to
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* 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_PRINTK macro
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*
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* Use this instead of calling printk to avoid unwanted compiler optimizations
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* which cause kpatch-build errors.
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*
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* The printk function is annotated with the __cold attribute, which tells gcc
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* that the function is unlikely to be called. A side effect of this is that
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* code paths containing calls to printk might also be marked cold, leading to
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* other functions called in those code paths getting moved into .text.unlikely
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* or being uninlined.
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*
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* This macro places printk in its own code path so as not to make the
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* surrounding code path cold.
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*/
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#define KPATCH_PRINTK(_fmt, ...) \
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({ \
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if (jiffies) \
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printk(_fmt, ## __VA_ARGS__); \
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})
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#endif /* __KPATCH_MACROS_H_ */
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