Documents the linux/marker.h header. Fix a bitwise flag manipulation mistake in the MARK_GENERIC macro.
Use the __marker (ro), new __marker_strings (ro) and __marker_data (rw) sections. It depends on the linker modification which defines this last section. It allows the use of a probe "private" data : upon probe connexion, it can provide a pointer to its own data structure which will be available at the probe call site as the pdata field of the mdata structure. With the new __marker_data section, much less data has to be defined in the kernel .data segment : only the enable flag, in non-optimized markers, is left in .data because it is used very often. The marker flags now only define MF_* which are bitmasks. There is no way to use the bitmask shift value, so it is less error prone. Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]> --- a/include/linux/marker.h +++ b/include/linux/marker.h @@ -16,48 +16,59 @@ #ifdef __KERNEL__ -typedef void marker_probe_func(const char *fmt, ...); +struct __mark_marker_data; -struct __mark_marker_c { +typedef void marker_probe_func(const struct __mark_marker_data *mdata, + const char *fmt, ...); + +struct __mark_marker_data { const char *name; - marker_probe_func **call; const char *format; int flags; + marker_probe_func *call; + void *pdata; } __attribute__((packed)); struct __mark_marker { - const struct __mark_marker_c *cmark; + struct __mark_marker_data *mdata; void *enable; } __attribute__((packed)); -/* Generic marker flavor always available */ #ifdef CONFIG_MARKERS -#define MF_OPTIMIZED 1 /* Use optimized markers */ -#define MF_LOCKDEP 2 /* Can call lockdep */ -#define MF_PRINTK 3 /* vprintk can be called in the probe */ +/* Marker flags : selects the mechanism used to connect the probes to the + * markers and what can be executed within the probes. This is primarily + * used at reentrancy-unfriendly sites. */ +#define MF_OPTIMIZED (1 << 0) /* Use optimized markers */ +#define MF_LOCKDEP (1 << 1) /* Can call lockdep */ +#define MF_PRINTK (1 << 2) /* vprintk can be called in the probe */ +#define _MF_NR 3 /* Number of marker flags */ -#define _MF_OPTIMIZED (1 << MF_OPTIMIZED) -#define _MF_LOCKDEP (1 << MF_LOCKDEP) -#define _MF_PRINTK (1 << MF_PRINTK) +#define DECLARE_MARKER_DATA(flags, name, format) \ +/* Generic marker flavor always available */ #define MARK_GENERIC(flags, name, format, args...) \ do { \ - static marker_probe_func *__mark_call_##name = \ - __mark_empty_function; \ + static const char __mstrtab_name_##name[] \ + __attribute__((section("__markers_strings"))) \ + = #name; \ + static const char __mstrtab_format_##name[] \ + __attribute__((section("__markers_strings"))) \ + = format; \ + static struct __mark_marker_data __mark_data_##name \ + __attribute__((section("__markers_data"))) = \ + { __mstrtab_name_##name, __mstrtab_format_##name, \ + (flags) & ~MF_OPTIMIZED, __mark_empty_function, NULL }; \ static char __marker_enable_##name = 0; \ - static const struct __mark_marker_c __mark_c_##name \ - __attribute__((section(".markers.c"))) = \ - { #name, &__mark_call_##name, format, \ - (flags) | ~_MF_OPTIMIZED } ; \ static const struct __mark_marker __mark_##name \ - __attribute__((section(".markers"))) = \ - { &__mark_c_##name, &__marker_enable_##name } ; \ + __attribute__((section("__markers"))) = \ + { &__mark_data_##name, &__marker_enable_##name } ; \ asm volatile ( "" : : "i" (&__mark_##name)); \ __mark_check_format(format, ## args); \ if (unlikely(__marker_enable_##name)) { \ preempt_disable(); \ - (*__mark_call_##name)(format, ## args); \ + (*__mark_data_##name.call)(&__mark_data_##name, \ + format, ## args); \ preempt_enable(); \ } \ } while (0) @@ -87,21 +98,23 @@ static inline int marker_generic_set_enable(void *address, char enable) #endif #define MARK_MAX_FORMAT_LEN 1024 +/* Pass this as a format string for a marker with no argument */ #define MARK_NOARGS " " -static inline __attribute__ ((format (printf, 1, 2))) +/* To be used for string format validity checking with sparse */ +static inline void __mark_check_format(const char *fmt, ...) { } extern marker_probe_func __mark_empty_function; extern int _marker_set_probe(int flags, const char *name, const char *format, - marker_probe_func *probe); + marker_probe_func *probe, void *pdata); -#define marker_set_probe(name, format, probe) \ - _marker_set_probe(_MF_DEFAULT, name, format, probe) +#define marker_set_probe(name, format, probe, pdata) \ + _marker_set_probe(MF_DEFAULT, name, format, probe, pdata) -extern int marker_remove_probe(marker_probe_func *probe); +extern int marker_remove_probe(const char *name); extern int marker_list_probe(marker_probe_func *probe); #endif /* __KERNEL__ */ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/