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add KPATCH_WARN_*_LINE macros

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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.
This commit is contained in:
Josh Poimboeuf 2014-07-09 10:34:22 -05:00
parent 6f38498d95
commit 57b51d0bdc
1 changed files with 40 additions and 0 deletions
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40
kmod/patch/kpatch-macros.h
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@ -2,6 +2,7 @@
#define __KPATCH_MACROS_H_
#include <linux/compiler.h>
#include <linux/bug.h>
typedef void (*kpatch_loadcall_t)(void);
typedef void (*kpatch_unloadcall_t)(void);
@ -64,4 +65,43 @@ struct kpatch_unload {
#define KPATCH_FORCE_UNSAFE(_fn) \
void *__kpatch_force_func_##_fn __section(.kpatch.force) = _fn;
/*
* KPATCH_WARN_*_LINE macros
*
* 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.
*
* TODO: consider moving these __WARN_*_line variants upstream to bug.h
*/
#ifndef __WARN_TAINT
#define __WARN_line(line) warn_slowpath_null(__FILE__, line)
#define __WARN_printf_line(line, arg...) warn_slowpath_fmt(__FILE__, line, arg)
#define __WARN_printf_taint_line(line, taint, arg...) \
warn_slowpath_fmt_taint(__FILE__, line, taint, arg)
#else
#error __WARN_TAINT not yet supported
#endif
#define KPATCH_WARN_LINE(line, condition, format...) ({ \
int __ret_warn_on = !!(condition); \
if (unlikely(__ret_warn_on)) \
__WARN_printf_line(line, format); \
unlikely(__ret_warn_on); \
})
#define KPATCH_WARN_ON_LINE(line, condition) ({ \
int __ret_warn_on = !!(condition); \
if (unlikely(__ret_warn_on)) \
__WARN_line(line); \
unlikely(__ret_warn_on); \
})
#define KPATCH_WARN_ON_SMP_LINE(line, condition) \
KPATCH_WARN_ON_LINE(line, condition)
#endif /* __KPATCH_MACROS_H_ */