4 * @remark Copyright 2004 Silicon Graphics Inc. All Rights Reserved.
5 * @remark Read the file COPYING
7 * @author Greg Banks <gnb@melbourne.sgi.com>
8 * @author Keith Owens <kaos@melbourne.sgi.com>
9 * Based on work done for the ia64 port of the SGI kernprof patch, which is
10 * Copyright (c) 2003-2004 Silicon Graphics Inc. All Rights Reserved.
13 #include <linux/oprofile.h>
14 #include <linux/sched.h>
16 #include <asm/ptrace.h>
17 #include <asm/system.h>
20 * For IA64 we need to perform a complex little dance to get both
21 * the struct pt_regs and a synthetic struct switch_stack in place
22 * to allow the unwind code to work. This dance requires our unwind
23 * using code to be called from a function called from unw_init_running().
24 * There we only get a single void* data pointer, so use this struct
25 * to hold all the data we need during the unwind.
31 struct unw_frame_info frame
;
32 u64
*prev_pfs_loc
; /* state for WAR for old spinlock ool code */
35 #if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 3)
37 * Returns non-zero if the PC is in the spinlock contention out-of-line code
38 * with non-standard calling sequence (on older compilers).
40 static __inline__
int in_old_ool_spinlock_code(unsigned long pc
)
42 extern const char ia64_spinlock_contention_pre3_4
[] __attribute__ ((weak
));
43 extern const char ia64_spinlock_contention_pre3_4_end
[] __attribute__ ((weak
));
44 unsigned long sc_start
= (unsigned long)ia64_spinlock_contention_pre3_4
;
45 unsigned long sc_end
= (unsigned long)ia64_spinlock_contention_pre3_4_end
;
46 return (sc_start
&& sc_end
&& pc
>= sc_start
&& pc
< sc_end
);
49 /* Newer spinlock code does a proper br.call and works fine with the unwinder */
50 #define in_old_ool_spinlock_code(pc) 0
53 /* Returns non-zero if the PC is in the Interrupt Vector Table */
54 static __inline__
int in_ivt_code(unsigned long pc
)
56 extern char ia64_ivt
[];
57 return (pc
>= (u_long
)ia64_ivt
&& pc
< (u_long
)ia64_ivt
+32768);
61 * Unwind to next stack frame.
63 static __inline__
int next_frame(ia64_backtrace_t
*bt
)
66 * Avoid unsightly console message from unw_unwind() when attempting
67 * to unwind through the Interrupt Vector Table which has no unwind
70 if (in_ivt_code(bt
->frame
.ip
))
74 * WAR for spinlock contention from leaf functions. ia64_spinlock_contention_pre3_4
75 * has ar.pfs == r0. Leaf functions do not modify ar.pfs so ar.pfs remains
76 * as 0, stopping the backtrace. Record the previous ar.pfs when the current
77 * IP is in ia64_spinlock_contention_pre3_4 then unwind, if pfs_loc has not changed
78 * after unwind then use pt_regs.ar_pfs which is where the real ar.pfs is for
81 if (bt
->prev_pfs_loc
&& bt
->regs
&& bt
->frame
.pfs_loc
== bt
->prev_pfs_loc
)
82 bt
->frame
.pfs_loc
= &bt
->regs
->ar_pfs
;
83 bt
->prev_pfs_loc
= (in_old_ool_spinlock_code(bt
->frame
.ip
) ? bt
->frame
.pfs_loc
: NULL
);
85 return unw_unwind(&bt
->frame
) == 0;
89 static void do_ia64_backtrace(struct unw_frame_info
*info
, void *vdata
)
91 ia64_backtrace_t
*bt
= vdata
;
92 struct switch_stack
*sw
;
96 sw
= (struct switch_stack
*)(info
+1);
97 /* padding from unw_init_running */
98 sw
= (struct switch_stack
*)(((unsigned long)sw
+ 15) & ~15);
100 unw_init_frame_info(&bt
->frame
, current
, sw
);
102 /* skip over interrupt frame and oprofile calls */
104 unw_get_sp(&bt
->frame
, &sp
);
105 if (sp
>= (u_long
)bt
->regs
)
109 } while (count
++ < 200);
111 /* finally, grab the actual sample */
112 while (bt
->depth
-- && next_frame(bt
)) {
113 unw_get_ip(&bt
->frame
, &pc
);
114 oprofile_add_trace(pc
);
115 if (unw_is_intr_frame(&bt
->frame
)) {
117 * Interrupt received on kernel stack; this can
118 * happen when timer interrupt fires while processing
119 * a softirq from the tail end of a hardware interrupt
120 * which interrupted a system call. Don't laugh, it
121 * happens! Splice the backtrace into two parts to
122 * avoid spurious cycles in the gprof output.
124 /* TODO: split rather than drop the 2nd half */
131 ia64_backtrace(struct pt_regs
* const regs
, unsigned int depth
)
137 * On IA64 there is little hope of getting backtraces from
138 * user space programs -- the problems of getting the unwind
139 * information from arbitrary user programs are extreme.
146 bt
.prev_pfs_loc
= NULL
;
147 local_irq_save(flags
);
148 unw_init_running(do_ia64_backtrace
, &bt
);
149 local_irq_restore(flags
);