// SPDX-License-Identifier: GPL-2.0-only

#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/uprobes.h>
#include <asm/insn.h>

#include "decode-insn.h"

#define UPROBE_TRAP_NR  UINT_MAX

bool is_swbp_insn(uprobe_opcode_t *insn)
{
#ifdef CONFIG_RISCV_ISA_C
        return (*insn & 0xffff) == UPROBE_SWBP_INSN;
#else
        return *insn == UPROBE_SWBP_INSN;
#endif
}

bool is_trap_insn(uprobe_opcode_t *insn)
{
        return riscv_insn_is_ebreak(*insn) || riscv_insn_is_c_ebreak(*insn);
}

unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
{
        return instruction_pointer(regs);
}

int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
                             unsigned long addr)
{
        probe_opcode_t opcode;

        opcode = *(probe_opcode_t *)(&auprobe->insn[0]);

        auprobe->insn_size = GET_INSN_LENGTH(opcode);

        switch (riscv_probe_decode_insn(&opcode, &auprobe->api)) {
        case INSN_REJECTED:
                return -EINVAL;

        case INSN_GOOD_NO_SLOT:
                auprobe->simulate = true;
                break;

        case INSN_GOOD:
                auprobe->simulate = false;
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
        struct uprobe_task *utask = current->utask;

        utask->autask.saved_cause = current->thread.bad_cause;
        current->thread.bad_cause = UPROBE_TRAP_NR;

        instruction_pointer_set(regs, utask->xol_vaddr);

        return 0;
}

int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
        struct uprobe_task *utask = current->utask;

        WARN_ON_ONCE(current->thread.bad_cause != UPROBE_TRAP_NR);
        current->thread.bad_cause = utask->autask.saved_cause;

        instruction_pointer_set(regs, utask->vaddr + auprobe->insn_size);

        return 0;
}

bool arch_uprobe_xol_was_trapped(struct task_struct *t)
{
        if (t->thread.bad_cause != UPROBE_TRAP_NR)
                return true;

        return false;
}

bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
        probe_opcode_t insn;
        unsigned long addr;

        if (!auprobe->simulate)
                return false;

        insn = *(probe_opcode_t *)(&auprobe->insn[0]);
        addr = instruction_pointer(regs);

        if (auprobe->api.handler)
                auprobe->api.handler(insn, addr, regs);

        return true;
}

void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
        struct uprobe_task *utask = current->utask;

        current->thread.bad_cause = utask->autask.saved_cause;
        /*
         * Task has received a fatal signal, so reset back to probbed
         * address.
         */
        instruction_pointer_set(regs, utask->vaddr);
}

bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
                struct pt_regs *regs)
{
        if (ctx == RP_CHECK_CHAIN_CALL)
                return regs->sp <= ret->stack;
        else
                return regs->sp < ret->stack;
}

unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
                                  struct pt_regs *regs)
{
        unsigned long ra;

        ra = regs->ra;

        regs->ra = trampoline_vaddr;

        return ra;
}

int arch_uprobe_exception_notify(struct notifier_block *self,
                                 unsigned long val, void *data)
{
        return NOTIFY_DONE;
}

bool uprobe_breakpoint_handler(struct pt_regs *regs)
{
        if (uprobe_pre_sstep_notifier(regs))
                return true;

        return false;
}

bool uprobe_single_step_handler(struct pt_regs *regs)
{
        if (uprobe_post_sstep_notifier(regs))
                return true;

        return false;
}

void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
                           void *src, unsigned long len)
{
        /* Initialize the slot */
        void *kaddr = kmap_local_page(page);
        void *dst = kaddr + (vaddr & ~PAGE_MASK);
        unsigned long start = (unsigned long)dst;

        memcpy(dst, src, len);

        /* Add ebreak behind opcode to simulate singlestep */
        if (vaddr) {
                dst += GET_INSN_LENGTH(*(probe_opcode_t *)src);
                *(uprobe_opcode_t *)dst = __BUG_INSN_32;
        }

        flush_icache_range(start, start + len);
        kunmap_local(kaddr);
}