// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Performance counter callchain support - powerpc architecture code
 *
 * Copyright © 2009 Paul Mackerras, IBM Corporation.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#include <asm/pte-walk.h>

#include "callchain.h"

/*
 * Is sp valid as the address of the next kernel stack frame after prev_sp?
 * The next frame may be in a different stack area but should not go
 * back down in the same stack area.
 */
static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
{
        if (sp & 0xf)
                return 0;               /* must be 16-byte aligned */
        if (!validate_sp(sp, current))
                return 0;
        if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
                return 1;
        /*
         * sp could decrease when we jump off an interrupt stack
         * back to the regular process stack.
         */
        if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
                return 1;
        return 0;
}

void __no_sanitize_address
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
        unsigned long sp, next_sp;
        unsigned long next_ip;
        unsigned long lr;
        long level = 0;
        unsigned long *fp;

        lr = regs->link;
        sp = regs->gpr[1];
        perf_callchain_store(entry, perf_arch_instruction_pointer(regs));

        if (!validate_sp(sp, current))
                return;

        for (;;) {
                fp = (unsigned long *) sp;
                next_sp = fp[0];

                if (next_sp == sp + STACK_INT_FRAME_SIZE &&
                    validate_sp_size(sp, current, STACK_INT_FRAME_SIZE) &&
                    fp[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
                        /*
                         * This looks like an interrupt frame for an
                         * interrupt that occurred in the kernel
                         */
                        regs = (struct pt_regs *)(sp + STACK_INT_FRAME_REGS);
                        next_ip = regs->nip;
                        lr = regs->link;
                        level = 0;
                        perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);

                } else {
                        if (level == 0)
                                next_ip = lr;
                        else
                                next_ip = fp[STACK_FRAME_LR_SAVE];

                        /*
                         * We can't tell which of the first two addresses
                         * we get are valid, but we can filter out the
                         * obviously bogus ones here.  We replace them
                         * with 0 rather than removing them entirely so
                         * that userspace can tell which is which.
                         */
                        if ((level == 1 && next_ip == lr) ||
                            (level <= 1 && !kernel_text_address(next_ip)))
                                next_ip = 0;

                        ++level;
                }

                perf_callchain_store(entry, next_ip);
                if (!valid_next_sp(next_sp, sp))
                        return;
                sp = next_sp;
        }
}

void
perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
        perf_callchain_store(entry, perf_arch_instruction_pointer(regs));

        if (!current->mm)
                return;

        if (!is_32bit_task())
                perf_callchain_user_64(entry, regs);
        else
                perf_callchain_user_32(entry, regs);
}