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(ctx: entry, ip: 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(ctx: entry, ip: 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(addr: next_ip))) |
91 | next_ip = 0; |
92 | |
93 | ++level; |
94 | } |
95 | |
96 | perf_callchain_store(ctx: entry, ip: next_ip); |
97 | if (!valid_next_sp(sp: next_sp, prev_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 | |