1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Linux performance counter support for MIPS.
4  *
5  * Copyright (C) 2010 MIPS Technologies, Inc.
6  * Author: Deng-Cheng Zhu
7  *
8  * This code is based on the implementation for ARM, which is in turn
9  * based on the sparc64 perf event code and the x86 code. Performance
10  * counter access is based on the MIPS Oprofile code. And the callchain
11  * support references the code of MIPS stacktrace.c.
12  */
13 
14 #include <linux/perf_event.h>
15 #include <linux/sched/task_stack.h>
16 
17 #include <asm/stacktrace.h>
18 
19 /* Callchain handling code. */
20 
21 /*
22  * Leave userspace callchain empty for now. When we find a way to trace
23  * the user stack callchains, we will add it here.
24  */
25 
save_raw_perf_callchain(struct perf_callchain_entry_ctx * entry,unsigned long reg29)26 static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
27 				    unsigned long reg29)
28 {
29 	unsigned long *sp = (unsigned long *)reg29;
30 	unsigned long addr;
31 
32 	while (!kstack_end(sp)) {
33 		addr = *sp++;
34 		if (__kernel_text_address(addr)) {
35 			perf_callchain_store(entry, addr);
36 			if (entry->nr >= entry->max_stack)
37 				break;
38 		}
39 	}
40 }
41 
perf_callchain_kernel(struct perf_callchain_entry_ctx * entry,struct pt_regs * regs)42 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
43 			   struct pt_regs *regs)
44 {
45 	unsigned long sp = regs->regs[29];
46 #ifdef CONFIG_KALLSYMS
47 	unsigned long ra = regs->regs[31];
48 	unsigned long pc = regs->cp0_epc;
49 
50 	if (raw_show_trace || !__kernel_text_address(pc)) {
51 		unsigned long stack_page =
52 			(unsigned long)task_stack_page(current);
53 		if (stack_page && sp >= stack_page &&
54 		    sp <= stack_page + THREAD_SIZE - 32)
55 			save_raw_perf_callchain(entry, sp);
56 		return;
57 	}
58 	do {
59 		perf_callchain_store(entry, pc);
60 		if (entry->nr >= entry->max_stack)
61 			break;
62 		pc = unwind_stack(current, &sp, pc, &ra);
63 	} while (pc);
64 #else
65 	save_raw_perf_callchain(entry, sp);
66 #endif
67 }
68