1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Performance counter callchain support - powerpc architecture code
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright © 2009 Paul Mackerras, IBM Corporation.
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun #include <linux/kernel.h>
8*4882a593Smuzhiyun #include <linux/sched.h>
9*4882a593Smuzhiyun #include <linux/perf_event.h>
10*4882a593Smuzhiyun #include <linux/percpu.h>
11*4882a593Smuzhiyun #include <linux/uaccess.h>
12*4882a593Smuzhiyun #include <linux/mm.h>
13*4882a593Smuzhiyun #include <asm/ptrace.h>
14*4882a593Smuzhiyun #include <asm/sigcontext.h>
15*4882a593Smuzhiyun #include <asm/ucontext.h>
16*4882a593Smuzhiyun #include <asm/vdso.h>
17*4882a593Smuzhiyun #include <asm/pte-walk.h>
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun #include "callchain.h"
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun /*
22*4882a593Smuzhiyun * Is sp valid as the address of the next kernel stack frame after prev_sp?
23*4882a593Smuzhiyun * The next frame may be in a different stack area but should not go
24*4882a593Smuzhiyun * back down in the same stack area.
25*4882a593Smuzhiyun */
valid_next_sp(unsigned long sp,unsigned long prev_sp)26*4882a593Smuzhiyun static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun if (sp & 0xf)
29*4882a593Smuzhiyun return 0; /* must be 16-byte aligned */
30*4882a593Smuzhiyun if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
31*4882a593Smuzhiyun return 0;
32*4882a593Smuzhiyun if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
33*4882a593Smuzhiyun return 1;
34*4882a593Smuzhiyun /*
35*4882a593Smuzhiyun * sp could decrease when we jump off an interrupt stack
36*4882a593Smuzhiyun * back to the regular process stack.
37*4882a593Smuzhiyun */
38*4882a593Smuzhiyun if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
39*4882a593Smuzhiyun return 1;
40*4882a593Smuzhiyun return 0;
41*4882a593Smuzhiyun }
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun void
perf_callchain_kernel(struct perf_callchain_entry_ctx * entry,struct pt_regs * regs)44*4882a593Smuzhiyun perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
45*4882a593Smuzhiyun {
46*4882a593Smuzhiyun unsigned long sp, next_sp;
47*4882a593Smuzhiyun unsigned long next_ip;
48*4882a593Smuzhiyun unsigned long lr;
49*4882a593Smuzhiyun long level = 0;
50*4882a593Smuzhiyun unsigned long *fp;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun lr = regs->link;
53*4882a593Smuzhiyun sp = regs->gpr[1];
54*4882a593Smuzhiyun perf_callchain_store(entry, perf_instruction_pointer(regs));
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
57*4882a593Smuzhiyun return;
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun for (;;) {
60*4882a593Smuzhiyun fp = (unsigned long *) sp;
61*4882a593Smuzhiyun next_sp = fp[0];
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun if (next_sp == sp + STACK_INT_FRAME_SIZE &&
64*4882a593Smuzhiyun fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
65*4882a593Smuzhiyun /*
66*4882a593Smuzhiyun * This looks like an interrupt frame for an
67*4882a593Smuzhiyun * interrupt that occurred in the kernel
68*4882a593Smuzhiyun */
69*4882a593Smuzhiyun regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
70*4882a593Smuzhiyun next_ip = regs->nip;
71*4882a593Smuzhiyun lr = regs->link;
72*4882a593Smuzhiyun level = 0;
73*4882a593Smuzhiyun perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun } else {
76*4882a593Smuzhiyun if (level == 0)
77*4882a593Smuzhiyun next_ip = lr;
78*4882a593Smuzhiyun else
79*4882a593Smuzhiyun next_ip = fp[STACK_FRAME_LR_SAVE];
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun /*
82*4882a593Smuzhiyun * We can't tell which of the first two addresses
83*4882a593Smuzhiyun * we get are valid, but we can filter out the
84*4882a593Smuzhiyun * obviously bogus ones here. We replace them
85*4882a593Smuzhiyun * with 0 rather than removing them entirely so
86*4882a593Smuzhiyun * that userspace can tell which is which.
87*4882a593Smuzhiyun */
88*4882a593Smuzhiyun if ((level == 1 && next_ip == lr) ||
89*4882a593Smuzhiyun (level <= 1 && !kernel_text_address(next_ip)))
90*4882a593Smuzhiyun next_ip = 0;
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun ++level;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun perf_callchain_store(entry, next_ip);
96*4882a593Smuzhiyun if (!valid_next_sp(next_sp, sp))
97*4882a593Smuzhiyun return;
98*4882a593Smuzhiyun sp = next_sp;
99*4882a593Smuzhiyun }
100*4882a593Smuzhiyun }
101*4882a593Smuzhiyun
102*4882a593Smuzhiyun void
perf_callchain_user(struct perf_callchain_entry_ctx * entry,struct pt_regs * regs)103*4882a593Smuzhiyun perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
104*4882a593Smuzhiyun {
105*4882a593Smuzhiyun if (!is_32bit_task())
106*4882a593Smuzhiyun perf_callchain_user_64(entry, regs);
107*4882a593Smuzhiyun else
108*4882a593Smuzhiyun perf_callchain_user_32(entry, regs);
109*4882a593Smuzhiyun }
110