// 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"

#ifdef CONFIG_PPC64
#include <asm/syscalls_32.h>
#else  /* CONFIG_PPC64 */

#define __SIGNAL_FRAMESIZE32    __SIGNAL_FRAMESIZE
#define sigcontext32            sigcontext
#define mcontext32              mcontext
#define ucontext32              ucontext
#define compat_siginfo_t        struct siginfo

#endif /* CONFIG_PPC64 */

static int read_user_stack_32(const unsigned int __user *ptr, unsigned int *ret)
{
        return __read_user_stack(ptr, ret, sizeof(*ret));
}

/*
 * Layout for non-RT signal frames
 */
struct signal_frame_32 {
        char                    dummy[__SIGNAL_FRAMESIZE32];
        struct sigcontext32     sctx;
        struct mcontext32       mctx;
        int                     abigap[56];
};

/*
 * Layout for RT signal frames
 */
struct rt_signal_frame_32 {
        char                    dummy[__SIGNAL_FRAMESIZE32 + 16];
        compat_siginfo_t        info;
        struct ucontext32       uc;
        int                     abigap[56];
};

static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
{
        if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
                return 1;
        if (current->mm->context.vdso &&
            nip == VDSO32_SYMBOL(current->mm->context.vdso, sigtramp32))
                return 1;
        return 0;
}

static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
{
        if (nip == fp + offsetof(struct rt_signal_frame_32,
                                 uc.uc_mcontext.mc_pad))
                return 1;
        if (current->mm->context.vdso &&
            nip == VDSO32_SYMBOL(current->mm->context.vdso, sigtramp_rt32))
                return 1;
        return 0;
}

static int sane_signal_32_frame(unsigned int sp)
{
        struct signal_frame_32 __user *sf;
        unsigned int regs;

        sf = (struct signal_frame_32 __user *) (unsigned long) sp;
        if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
                return 0;
        return regs == (unsigned long) &sf->mctx;
}

static int sane_rt_signal_32_frame(unsigned int sp)
{
        struct rt_signal_frame_32 __user *sf;
        unsigned int regs;

        sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
        if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
                return 0;
        return regs == (unsigned long) &sf->uc.uc_mcontext;
}

static unsigned int __user *signal_frame_32_regs(unsigned int sp,
                                unsigned int next_sp, unsigned int next_ip)
{
        struct mcontext32 __user *mctx = NULL;
        struct signal_frame_32 __user *sf;
        struct rt_signal_frame_32 __user *rt_sf;

        /*
         * Note: the next_sp - sp >= signal frame size check
         * is true when next_sp < sp, for example, when
         * transitioning from an alternate signal stack to the
         * normal stack.
         */
        if (next_sp - sp >= sizeof(struct signal_frame_32) &&
            is_sigreturn_32_address(next_ip, sp) &&
            sane_signal_32_frame(sp)) {
                sf = (struct signal_frame_32 __user *) (unsigned long) sp;
                mctx = &sf->mctx;
        }

        if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
            is_rt_sigreturn_32_address(next_ip, sp) &&
            sane_rt_signal_32_frame(sp)) {
                rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
                mctx = &rt_sf->uc.uc_mcontext;
        }

        if (!mctx)
                return NULL;
        return mctx->mc_gregs;
}

void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
                            struct pt_regs *regs)
{
        unsigned int sp, next_sp;
        unsigned int next_ip;
        unsigned int lr;
        long level = 0;
        unsigned int __user *fp, *uregs;

        next_ip = perf_arch_instruction_pointer(regs);
        lr = regs->link;
        sp = regs->gpr[1];

        while (entry->nr < entry->max_stack) {
                fp = (unsigned int __user *) (unsigned long) sp;
                if (invalid_user_sp(sp) || read_user_stack_32(fp, &next_sp))
                        return;
                if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
                        return;

                uregs = signal_frame_32_regs(sp, next_sp, next_ip);
                if (!uregs && level <= 1)
                        uregs = signal_frame_32_regs(sp, next_sp, lr);
                if (uregs) {
                        /*
                         * This looks like an signal frame, so restart
                         * the stack trace with the values in it.
                         */
                        if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
                            read_user_stack_32(&uregs[PT_LNK], &lr) ||
                            read_user_stack_32(&uregs[PT_R1], &sp))
                                return;
                        level = 0;
                        perf_callchain_store_context(entry, PERF_CONTEXT_USER);
                        perf_callchain_store(entry, next_ip);
                        continue;
                }

                if (level == 0)
                        next_ip = lr;
                perf_callchain_store(entry, next_ip);
                ++level;
                sp = next_sp;
        }
}