1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Performance counter callchain support - powerpc architecture code
4 *
5 * Copyright © 2009 Paul Mackerras, IBM Corporation.
6 */
7 #include <linux/kernel.h>
8 #include <linux/sched.h>
9 #include <linux/perf_event.h>
10 #include <linux/percpu.h>
11 #include <linux/uaccess.h>
12 #include <linux/mm.h>
13 #include <asm/ptrace.h>
14 #include <asm/sigcontext.h>
15 #include <asm/ucontext.h>
16 #include <asm/vdso.h>
17 #include <asm/pte-walk.h>
18
19 #include "callchain.h"
20
21 /*
22 * Is sp valid as the address of the next kernel stack frame after prev_sp?
23 * The next frame may be in a different stack area but should not go
24 * back down in the same stack area.
25 */
26 static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
27 {
28 if (sp & 0xf)
29 return 0; /* must be 16-byte aligned */
30 if (!validate_sp(sp, current))
31 return 0;
32 if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
33 return 1;
34 /*
35 * sp could decrease when we jump off an interrupt stack
36 * back to the regular process stack.
37 */
38 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
39 return 1;
40 return 0;
41 }
42
43 void __no_sanitize_address
44 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
45 {
46 unsigned long sp, next_sp;
47 unsigned long next_ip;
48 unsigned long lr;
49 long level = 0;
50 unsigned long *fp;
51
52 lr = regs->link;
53 sp = regs->gpr[1];
54 perf_callchain_store(entry, perf_instruction_pointer(regs));
55
56 if (!validate_sp(sp, current))
57 return;
58
59 for (;;) {
60 fp = (unsigned long *) sp;
61 next_sp = fp[0];
62
63 if (next_sp == sp + STACK_INT_FRAME_SIZE &&
64 validate_sp_size(sp, current, STACK_INT_FRAME_SIZE) &&
65 fp[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
66 /*
67 * This looks like an interrupt frame for an
68 * interrupt that occurred in the kernel
69 */
70 regs = (struct pt_regs *)(sp + STACK_INT_FRAME_REGS);
71 next_ip = regs->nip;
72 lr = regs->link;
73 level = 0;
74 perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
75
76 } else {
77 if (level == 0)
78 next_ip = lr;
79 else
80 next_ip = fp[STACK_FRAME_LR_SAVE];
81
82 /*
83 * We can't tell which of the first two addresses
84 * we get are valid, but we can filter out the
85 * obviously bogus ones here. We replace them
86 * with 0 rather than removing them entirely so
87 * that userspace can tell which is which.
88 */
89 if ((level == 1 && next_ip == lr) ||
90 (level <= 1 && !kernel_text_address(next_ip)))
91 next_ip = 0;
92
93 ++level;
94 }
95
96 perf_callchain_store(entry, next_ip);
97 if (!valid_next_sp(next_sp, sp))
98 return;
99 sp = next_sp;
100 }
101 }
102
103 void
104 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
105 {
106 if (!is_32bit_task())
107 perf_callchain_user_64(entry, regs);
108 else
109 perf_callchain_user_32(entry, regs);
110 }
111
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