// SPDX-License-Identifier: GPL-2.0-only
/*
 * Linux performance counter support for MIPS.
 *
 * Copyright (C) 2010 MIPS Technologies, Inc.
 * Author: Deng-Cheng Zhu
 *
 * This code is based on the implementation for ARM, which is in turn
 * based on the sparc64 perf event code and the x86 code. Performance
 * counter access is based on the MIPS Oprofile code. And the callchain
 * support references the code of MIPS stacktrace.c.
 */

#include <linux/perf_event.h>
#include <linux/sched/task_stack.h>

#include <asm/stacktrace.h>

/* Callchain handling code. */

/*
 * Leave userspace callchain empty for now. When we find a way to trace
 * the user stack callchains, we will add it here.
 */

static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
                                    unsigned long reg29)
{
        unsigned long *sp = (unsigned long *)reg29;
        unsigned long addr;

        while (!kstack_end(sp)) {
                addr = *sp++;
                if (__kernel_text_address(addr)) {
                        perf_callchain_store(entry, addr);
                        if (entry->nr >= entry->max_stack)
                                break;
                }
        }
}

void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
                           struct pt_regs *regs)
{
        unsigned long sp = regs->regs[29];
#ifdef CONFIG_KALLSYMS
        unsigned long ra = regs->regs[31];
        unsigned long pc = regs->cp0_epc;

        if (raw_show_trace || !__kernel_text_address(pc)) {
                unsigned long stack_page =
                        (unsigned long)task_stack_page(current);
                if (stack_page && sp >= stack_page &&
                    sp <= stack_page + THREAD_SIZE - 32)
                        save_raw_perf_callchain(entry, sp);
                return;
        }
        do {
                perf_callchain_store(entry, pc);
                if (entry->nr >= entry->max_stack)
                        break;
                pc = unwind_stack(current, &sp, pc, &ra);
        } while (pc);
#else
        save_raw_perf_callchain(entry, sp);
#endif
}