1 /*
2 * Perf callchain handling code.
3 *
4 * Based on the ARM perf implementation.
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/sched.h>
9 #include <linux/perf_event.h>
10 #include <linux/uaccess.h>
11 #include <asm/ptrace.h>
12 #include <asm/stacktrace.h>
13
is_valid_call(unsigned long calladdr)14 static bool is_valid_call(unsigned long calladdr)
15 {
16 unsigned int callinsn;
17
18 /* Check the possible return address is aligned. */
19 if (!(calladdr & 0x3)) {
20 if (!get_user(callinsn, (unsigned int *)calladdr)) {
21 /* Check for CALLR or SWAP PC,D1RtP. */
22 if ((callinsn & 0xff000000) == 0xab000000 ||
23 callinsn == 0xa3200aa0)
24 return true;
25 }
26 }
27 return false;
28 }
29
30 static struct metag_frame __user *
user_backtrace(struct metag_frame __user * user_frame,struct perf_callchain_entry * entry)31 user_backtrace(struct metag_frame __user *user_frame,
32 struct perf_callchain_entry *entry)
33 {
34 struct metag_frame frame;
35 unsigned long calladdr;
36
37 /* We cannot rely on having frame pointers in user code. */
38 while (1) {
39 /* Also check accessibility of one struct frame beyond */
40 if (!access_ok(VERIFY_READ, user_frame, sizeof(frame)))
41 return 0;
42 if (__copy_from_user_inatomic(&frame, user_frame,
43 sizeof(frame)))
44 return 0;
45
46 --user_frame;
47
48 calladdr = frame.lr - 4;
49 if (is_valid_call(calladdr)) {
50 perf_callchain_store(entry, calladdr);
51 return user_frame;
52 }
53 }
54
55 return 0;
56 }
57
58 void
perf_callchain_user(struct perf_callchain_entry * entry,struct pt_regs * regs)59 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
60 {
61 unsigned long sp = regs->ctx.AX[0].U0;
62 struct metag_frame __user *frame;
63
64 frame = (struct metag_frame __user *)sp;
65
66 --frame;
67
68 while ((entry->nr < PERF_MAX_STACK_DEPTH) && frame)
69 frame = user_backtrace(frame, entry);
70 }
71
72 /*
73 * Gets called by walk_stackframe() for every stackframe. This will be called
74 * whist unwinding the stackframe and is like a subroutine return so we use
75 * the PC.
76 */
77 static int
callchain_trace(struct stackframe * fr,void * data)78 callchain_trace(struct stackframe *fr,
79 void *data)
80 {
81 struct perf_callchain_entry *entry = data;
82 perf_callchain_store(entry, fr->pc);
83 return 0;
84 }
85
86 void
perf_callchain_kernel(struct perf_callchain_entry * entry,struct pt_regs * regs)87 perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
88 {
89 struct stackframe fr;
90
91 fr.fp = regs->ctx.AX[1].U0;
92 fr.sp = regs->ctx.AX[0].U0;
93 fr.lr = regs->ctx.DX[4].U1;
94 fr.pc = regs->ctx.CurrPC;
95 walk_stackframe(&fr, callchain_trace, entry);
96 }
97