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 */
26static 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
43void __no_sanitize_address
44perf_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
103void
104perf_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