Linux Kernel  3.7.1
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op_model_ev4.c
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1 
10 #include <linux/oprofile.h>
11 #include <linux/init.h>
12 #include <linux/smp.h>
13 #include <asm/ptrace.h>
14 
15 #include "op_impl.h"
16 
17 
18 /* Compute all of the registers in preparation for enabling profiling. */
19 
20 static void
21 ev4_reg_setup(struct op_register_config *reg,
22  struct op_counter_config *ctr,
23  struct op_system_config *sys)
24 {
25  unsigned long ctl = 0, count, hilo;
26 
27  /* Select desired events. We've mapped the event numbers
28  such that they fit directly into the event selection fields.
29 
30  Note that there is no "off" setting. In both cases we select
31  the EXTERNAL event source, hoping that it'll be the lowest
32  frequency, and set the frequency counter to LOW. The interrupts
33  for these "disabled" counter overflows are ignored by the
34  interrupt handler.
35 
36  This is most irritating, because the hardware *can* enable and
37  disable the interrupts for these counters independently, but the
38  wrperfmon interface doesn't allow it. */
39 
40  ctl |= (ctr[0].enabled ? ctr[0].event << 8 : 14 << 8);
41  ctl |= (ctr[1].enabled ? (ctr[1].event - 16) << 32 : 7ul << 32);
42 
43  /* EV4 can not read or write its counter registers. The only
44  thing one can do at all is see if you overflow and get an
45  interrupt. We can set the width of the counters, to some
46  extent. Take the interrupt count selected by the user,
47  map it onto one of the possible values, and write it back. */
48 
49  count = ctr[0].count;
50  if (count <= 4096)
51  count = 4096, hilo = 1;
52  else
53  count = 65536, hilo = 0;
54  ctr[0].count = count;
55  ctl |= (ctr[0].enabled && hilo) << 3;
56 
57  count = ctr[1].count;
58  if (count <= 256)
59  count = 256, hilo = 1;
60  else
61  count = 4096, hilo = 0;
62  ctr[1].count = count;
63  ctl |= (ctr[1].enabled && hilo);
64 
65  reg->mux_select = ctl;
66 
67  /* Select performance monitoring options. */
68  /* ??? Need to come up with some mechanism to trace only
69  selected processes. EV4 does not have a mechanism to
70  select kernel or user mode only. For now, enable always. */
71  reg->proc_mode = 0;
72 
73  /* Frequency is folded into mux_select for EV4. */
74  reg->freq = 0;
75 
76  /* See above regarding no writes. */
77  reg->reset_values = 0;
78  reg->need_reset = 0;
79 
80 }
81 
82 /* Program all of the registers in preparation for enabling profiling. */
83 
84 static void
85 ev4_cpu_setup(void *x)
86 {
87  struct op_register_config *reg = x;
88 
89  wrperfmon(2, reg->mux_select);
90  wrperfmon(3, reg->proc_mode);
91 }
92 
93 static void
94 ev4_handle_interrupt(unsigned long which, struct pt_regs *regs,
95  struct op_counter_config *ctr)
96 {
97  /* EV4 can't properly disable counters individually.
98  Discard "disabled" events now. */
99  if (!ctr[which].enabled)
100  return;
101 
102  /* Record the sample. */
103  oprofile_add_sample(regs, which);
104 }
105 
106 
108  .reg_setup = ev4_reg_setup,
109  .cpu_setup = ev4_cpu_setup,
110  .reset_ctr = NULL,
111  .handle_interrupt = ev4_handle_interrupt,
112  .cpu_type = "alpha/ev4",
113  .num_counters = 2,
114  .can_set_proc_mode = 0,
115 };