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 */
valid_next_sp(unsigned long sp,unsigned long prev_sp)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, STACK_FRAME_OVERHEAD))
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
perf_callchain_kernel(struct perf_callchain_entry_ctx * entry,struct pt_regs * regs)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, STACK_FRAME_OVERHEAD))
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 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
65 /*
66 * This looks like an interrupt frame for an
67 * interrupt that occurred in the kernel
68 */
69 regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
70 next_ip = regs->nip;
71 lr = regs->link;
72 level = 0;
73 perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
74
75 } else {
76 if (level == 0)
77 next_ip = lr;
78 else
79 next_ip = fp[STACK_FRAME_LR_SAVE];
80
81 /*
82 * We can't tell which of the first two addresses
83 * we get are valid, but we can filter out the
84 * obviously bogus ones here. We replace them
85 * with 0 rather than removing them entirely so
86 * that userspace can tell which is which.
87 */
88 if ((level == 1 && next_ip == lr) ||
89 (level <= 1 && !kernel_text_address(next_ip)))
90 next_ip = 0;
91
92 ++level;
93 }
94
95 perf_callchain_store(entry, next_ip);
96 if (!valid_next_sp(next_sp, sp))
97 return;
98 sp = next_sp;
99 }
100 }
101
102 void
perf_callchain_user(struct perf_callchain_entry_ctx * entry,struct pt_regs * regs)103 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
104 {
105 if (!is_32bit_task())
106 perf_callchain_user_64(entry, regs);
107 else
108 perf_callchain_user_32(entry, regs);
109 }
110