// SPDX-License-Identifier: GPL-2.0
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/list.h>
#include <trace/syscall.h>

#include <asm/ftrace.h>

#ifdef CONFIG_DYNAMIC_FTRACE
static const u32 ftrace_nop = 0x01000000;

static u32 ftrace_call_replace(unsigned long ip, unsigned long addr)
{
        u32 call;
        s32 off;

        off = ((s32)addr - (s32)ip);
        call = 0x40000000 | ((u32)off >> 2);

        return call;
}

static int ftrace_modify_code(unsigned long ip, u32 old, u32 new)
{
        u32 replaced;
        int faulted;

        __asm__ __volatile__(
        "1:     cas     [%[ip]], %[old], %[new]\n"
        "       flush   %[ip]\n"
        "       mov     0, %[faulted]\n"
        "2:\n"
        "       .section .fixup,#alloc,#execinstr\n"
        "       .align  4\n"
        "3:     sethi   %%hi(2b), %[faulted]\n"
        "       jmpl    %[faulted] + %%lo(2b), %%g0\n"
        "        mov    1, %[faulted]\n"
        "       .previous\n"
        "       .section __ex_table,\"a\"\n"
        "       .align  4\n"
        "       .word   1b, 3b\n"
        "       .previous\n"
        : "=r" (replaced), [faulted] "=r" (faulted)
        : [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
        : "memory");

        if (replaced != old && replaced != new)
                faulted = 2;

        return faulted;
}

int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
{
        unsigned long ip = rec->ip;
        u32 old, new;

        old = ftrace_call_replace(ip, addr);
        new = ftrace_nop;
        return ftrace_modify_code(ip, old, new);
}

int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
        unsigned long ip = rec->ip;
        u32 old, new;

        old = ftrace_nop;
        new = ftrace_call_replace(ip, addr);
        return ftrace_modify_code(ip, old, new);
}

int ftrace_update_ftrace_func(ftrace_func_t func)
{
        unsigned long ip = (unsigned long)(&ftrace_call);
        u32 old, new;

        old = *(u32 *) &ftrace_call;
        new = ftrace_call_replace(ip, (unsigned long)func);
        return ftrace_modify_code(ip, old, new);
}
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void);

int ftrace_enable_ftrace_graph_caller(void)
{
        unsigned long ip = (unsigned long)(&ftrace_graph_call);
        u32 old, new;

        old = *(u32 *) &ftrace_graph_call;
        new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller);
        return ftrace_modify_code(ip, old, new);
}

int ftrace_disable_ftrace_graph_caller(void)
{
        unsigned long ip = (unsigned long)(&ftrace_graph_call);
        u32 old, new;

        old = *(u32 *) &ftrace_graph_call;
        new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub);

        return ftrace_modify_code(ip, old, new);
}

#endif /* !CONFIG_DYNAMIC_FTRACE */

/*
 * Hook the return address and push it in the stack of return addrs
 * in current thread info.
 */
unsigned long prepare_ftrace_return(unsigned long parent,
                                    unsigned long self_addr,
                                    unsigned long frame_pointer)
{
        unsigned long return_hooker = (unsigned long) &return_to_handler;

        if (unlikely(atomic_read(&current->tracing_graph_pause)))
                return parent + 8UL;

        if (function_graph_enter(parent, self_addr, frame_pointer, NULL))
                return parent + 8UL;

        return return_hooker;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */