Document the i386 marker header, change it to use the __marker,
__marker_data and __marker_strings sections. Change the flag usage to
use MF_* directly (which is now a bitmask). In marker.c, for the i386
optimized marker enabling, check the a simple test is the value will be
changed. If not, simply return : we would set it to the same value
anyway.
Signed-off-by: Mathieu Desnoyers <[email protected]>
--- a/include/asm-i386/marker.h
+++ b/include/asm-i386/marker.h
@@ -1,3 +1,6 @@
+#ifndef _ASM_I386_MARKER_H
+#define _ASM_I386_MARKER_H
+
/*
* marker.h
*
@@ -12,42 +15,54 @@
#ifdef CONFIG_MARKERS
-#define _MF_DEFAULT (_MF_OPTIMIZED | _MF_LOCKDEP | _MF_PRINTK)
+#define MF_DEFAULT (MF_OPTIMIZED | MF_LOCKDEP | MF_PRINTK)
+/* Optimized version of the markers */
#define MARK_OPTIMIZED(flags, name, format, args...) \
do { \
- static marker_probe_func *__mark_call_##name = \
- __mark_empty_function; \
- static const struct __mark_marker_c __mark_c_##name \
- __attribute__((section(".markers.c"))) = \
- { #name, &__mark_call_##name, format, \
- (flags) | _MF_OPTIMIZED } ; \
+ 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 }; \
char condition; \
- asm volatile( ".section .markers, \"a\", @progbits;\n\t" \
+ asm volatile( ".section __markers, \"a\", @progbits;\n\t" \
".long %1, 0f;\n\t" \
".previous;\n\t" \
".align 2\n\t" \
"0:\n\t" \
"movb $0,%0;\n\t" \
: "=r" (condition) \
- : "m" (__mark_c_##name)); \
+ : "m" (__mark_data_##name)); \
__mark_check_format(format, ## args); \
if (unlikely(condition)) { \
preempt_disable(); \
- (*__mark_call_##name)(format, ## args); \
+ (*__mark_data_##name.call)(&__mark_data_##name, \
+ format, ## args); \
preempt_enable(); \
} \
} while (0)
+/* Marker macro selecting the generic or optimized version of marker, depending
+ * on the flags specified. */
#define _MARK(flags, format, args...) \
do { \
- if (((flags) & _MF_LOCKDEP) && ((flags) & _MF_OPTIMIZED)) \
+ if (((flags) & MF_LOCKDEP) && ((flags) & MF_OPTIMIZED)) \
MARK_OPTIMIZED(flags, format, ## args); \
else \
MARK_GENERIC(flags, format, ## args); \
} while (0)
-#define MARK(format, args...) _MARK(_MF_DEFAULT, format, ## args)
+/* Marker with default behavior */
+#define MARK(format, args...) _MARK(MF_DEFAULT, format, ## args)
+
+/* Architecture dependant marker information, used internally for marker
+ * activation. */
/* Offset of the immediate value from the start of the movb instruction, in
* bytes. */
@@ -61,3 +76,4 @@ do { \
extern int marker_optimized_set_enable(void *address, char enable);
#endif
+#endif //_ASM_I386_MARKER_H
--- a/arch/i386/kernel/marker.c
+++ b/arch/i386/kernel/marker.c
@@ -4,7 +4,9 @@
*
* Permits marker activation by XMC with correct serialization.
*
- * Reentrant for NMI and trap handler instrumentation. :-)
+ * Reentrant for NMI and trap handler instrumentation. Permits XMC to a
+ * location that has preemption enabled because it involves no temporary or
+ * reused data structure.
*
* Mathieu Desnoyers <[email protected]>
*/
@@ -63,8 +65,10 @@ int marker_optimized_set_enable(void *address, char enable)
int ret;
char *dest = address;
+ if (!(enable ^ dest[1])) /* Must be a state change 0<->1 to execute */
+ return 0;
+
mutex_lock(&mark_mutex);
- BUG_ON(!(enable ^ dest[1])); /* Must be a state change 0<->1 */
target_eip = (long)address + BREAKPOINT_INS_LEN;
/* register_die_notifier has memory barriers */
register_die_notifier(&mark_notify);
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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