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 static int read_user_stack_64(const unsigned long __user *ptr, unsigned long *ret)
22 {
23 return __read_user_stack(ptr, ret, sizeof(*ret));
24 }
25
26 /*
27 * 64-bit user processes use the same stack frame for RT and non-RT signals.
28 */
29 struct signal_frame_64 {
30 char dummy[__SIGNAL_FRAMESIZE];
31 struct ucontext uc;
32 unsigned long unused[2];
33 unsigned int tramp[6];
34 struct siginfo *pinfo;
35 void *puc;
36 struct siginfo info;
37 char abigap[288];
38 };
39
40 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
41 {
42 if (nip == fp + offsetof(struct signal_frame_64, tramp))
43 return 1;
44 if (current->mm->context.vdso &&
45 nip == VDSO64_SYMBOL(current->mm->context.vdso, sigtramp_rt64))
46 return 1;
47 return 0;
48 }
49
50 /*
51 * Do some sanity checking on the signal frame pointed to by sp.
52 * We check the pinfo and puc pointers in the frame.
53 */
54 static int sane_signal_64_frame(unsigned long sp)
55 {
56 struct signal_frame_64 __user *sf;
57 unsigned long pinfo, puc;
58
59 sf = (struct signal_frame_64 __user *) sp;
60 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
61 read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
62 return 0;
63 return pinfo == (unsigned long) &sf->info &&
64 puc == (unsigned long) &sf->uc;
65 }
66
67 void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
68 struct pt_regs *regs)
69 {
70 unsigned long sp, next_sp;
71 unsigned long next_ip;
72 unsigned long lr;
73 long level = 0;
74 struct signal_frame_64 __user *sigframe;
75 unsigned long __user *fp, *uregs;
76
77 next_ip = perf_instruction_pointer(regs);
78 lr = regs->link;
79 sp = regs->gpr[1];
80 perf_callchain_store(entry, next_ip);
81
82 while (entry->nr < entry->max_stack) {
83 fp = (unsigned long __user *) sp;
84 if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp))
85 return;
86 if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
87 return;
88
89 /*
90 * Note: the next_sp - sp >= signal frame size check
91 * is true when next_sp < sp, which can happen when
92 * transitioning from an alternate signal stack to the
93 * normal stack.
94 */
95 if (next_sp - sp >= sizeof(struct signal_frame_64) &&
96 (is_sigreturn_64_address(next_ip, sp) ||
97 (level <= 1 && is_sigreturn_64_address(lr, sp))) &&
98 sane_signal_64_frame(sp)) {
99 /*
100 * This looks like an signal frame
101 */
102 sigframe = (struct signal_frame_64 __user *) sp;
103 uregs = sigframe->uc.uc_mcontext.gp_regs;
104 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
105 read_user_stack_64(&uregs[PT_LNK], &lr) ||
106 read_user_stack_64(&uregs[PT_R1], &sp))
107 return;
108 level = 0;
109 perf_callchain_store_context(entry, PERF_CONTEXT_USER);
110 perf_callchain_store(entry, next_ip);
111 continue;
112 }
113
114 if (level == 0)
115 next_ip = lr;
116 perf_callchain_store(entry, next_ip);
117 ++level;
118 sp = next_sp;
119 }
120 }
121
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