// SPDX-License-Identifier: GPL-2.0-only
/*
 * Stack trace management functions
 *
 *  Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
 */
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
#include <linux/export.h>
#include <asm/stacktrace.h>

/*
 * Save stack-backtrace addresses into a stack_trace buffer:
 */
static void save_raw_context_stack(struct stack_trace *trace,
        unsigned long reg29, int savesched)
{
        unsigned long *sp = (unsigned long *)reg29;
        unsigned long addr;

        while (!kstack_end(sp)) {
                addr = *sp++;
                if (__kernel_text_address(addr) &&
                    (savesched || !in_sched_functions(addr))) {
                        if (trace->skip > 0)
                                trace->skip--;
                        else
                                trace->entries[trace->nr_entries++] = addr;
                        if (trace->nr_entries >= trace->max_entries)
                                break;
                }
        }
}

static void save_context_stack(struct stack_trace *trace,
        struct task_struct *tsk, struct pt_regs *regs, int savesched)
{
        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(tsk);
                if (stack_page && sp >= stack_page &&
                    sp <= stack_page + THREAD_SIZE - 32)
                        save_raw_context_stack(trace, sp, savesched);
                return;
        }
        do {
                if (savesched || !in_sched_functions(pc)) {
                        if (trace->skip > 0)
                                trace->skip--;
                        else
                                trace->entries[trace->nr_entries++] = pc;
                        if (trace->nr_entries >= trace->max_entries)
                                break;
                }
                pc = unwind_stack(tsk, &sp, pc, &ra);
        } while (pc);
#else
        save_raw_context_stack(trace, sp, savesched);
#endif
}

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
void save_stack_trace(struct stack_trace *trace)
{
        save_stack_trace_tsk(current, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
        struct pt_regs dummyregs;
        struct pt_regs *regs = &dummyregs;

        WARN_ON(trace->nr_entries || !trace->max_entries);

        if (tsk != current) {
                regs->regs[29] = tsk->thread.reg29;
                regs->regs[31] = 0;
                regs->cp0_epc = tsk->thread.reg31;
        } else
                prepare_frametrace(regs);
        save_context_stack(trace, tsk, regs, tsk == current);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);