// SPDX-License-Identifier: GPL-2.0
/*
 * Code for tracing calls in Linux kernel.
 * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
 *
 * based on code for x86 which is:
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 *
 * future possible enhancements:
 *      - add CONFIG_STACK_TRACER
 */

#include <linux/init.h>
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/jump_label.h>

#include <asm/assembly.h>
#include <asm/sections.h>
#include <asm/ftrace.h>
#include <asm/text-patching.h>

#define __hot __section(".text.hot")

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static DEFINE_STATIC_KEY_FALSE(ftrace_graph_enable);

/*
 * Hook the return address and push it in the stack of return addrs
 * in current thread info.
 */
static void __hot prepare_ftrace_return(unsigned long *parent,
                                        unsigned long self_addr)
{
        unsigned long old;
        extern int parisc_return_to_handler;

        if (unlikely(ftrace_graph_is_dead()))
                return;

        if (unlikely(atomic_read(&current->tracing_graph_pause)))
                return;

        old = *parent;

        if (!function_graph_enter(old, self_addr, 0, NULL))
                /* activate parisc_return_to_handler() as return point */
                *parent = (unsigned long) &parisc_return_to_handler;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

static ftrace_func_t ftrace_func;

asmlinkage void notrace __hot ftrace_function_trampoline(unsigned long parent,
                                unsigned long self_addr,
                                unsigned long org_sp_gr3,
                                struct ftrace_regs *fregs)
{
        extern struct ftrace_ops *function_trace_op;

        ftrace_func(self_addr, parent, function_trace_op, fregs);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        if (static_branch_unlikely(&ftrace_graph_enable)) {
                unsigned long *parent_rp;

                /* calculate pointer to %rp in stack */
                parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
                /* sanity check: parent_rp should hold parent */
                if (*parent_rp != parent)
                        return;

                prepare_ftrace_return(parent_rp, self_addr);
                return;
        }
#endif
}

#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_FUNCTION_GRAPH_TRACER)
int ftrace_enable_ftrace_graph_caller(void)
{
        static_key_enable(&ftrace_graph_enable.key);
        return 0;
}

int ftrace_disable_ftrace_graph_caller(void)
{
        static_key_disable(&ftrace_graph_enable.key);
        return 0;
}
#endif

#ifdef CONFIG_DYNAMIC_FTRACE
int ftrace_update_ftrace_func(ftrace_func_t func)
{
        ftrace_func = func;
        return 0;
}

int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
                        unsigned long addr)
{
        return 0;
}

unsigned long ftrace_call_adjust(unsigned long addr)
{
        return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
}

int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
        u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
        u32 *tramp;
        int size, ret, i;
        void *ip;

#ifdef CONFIG_64BIT
        unsigned long addr2 =
                (unsigned long)dereference_function_descriptor((void *)addr);

        u32 ftrace_trampoline[] = {
                0x73c10208, /* std,ma r1,100(sp) */
                0x0c2110c1, /* ldd -10(r1),r1 */
                0xe820d002, /* bve,n (r1) */
                addr2 >> 32,
                addr2 & 0xffffffff,
                0xe83f1fd7, /* b,l,n .-14,r1 */
        };

        u32 ftrace_trampoline_unaligned[] = {
                addr2 >> 32,
                addr2 & 0xffffffff,
                0x37de0200, /* ldo 100(sp),sp */
                0x73c13e01, /* std r1,-100(sp) */
                0x34213ff9, /* ldo -4(r1),r1 */
                0x50213fc1, /* ldd -20(r1),r1 */
                0xe820d002, /* bve,n (r1) */
                0xe83f1fcf, /* b,l,n .-20,r1 */
        };

        BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) >
                                FTRACE_PATCHABLE_FUNCTION_SIZE);
#else
        u32 ftrace_trampoline[] = {
                (u32)addr,
                0x6fc10080, /* stw,ma r1,40(sp) */
                0x48213fd1, /* ldw -18(r1),r1 */
                0xe820c002, /* bv,n r0(r1) */
                0xe83f1fdf, /* b,l,n .-c,r1 */
        };
#endif

        BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) >
                                FTRACE_PATCHABLE_FUNCTION_SIZE);

        size = sizeof(ftrace_trampoline);
        tramp = ftrace_trampoline;

#ifdef CONFIG_64BIT
        if (rec->ip & 0x4) {
                size = sizeof(ftrace_trampoline_unaligned);
                tramp = ftrace_trampoline_unaligned;
        }
#endif

        ip = (void *)(rec->ip + 4 - size);

        ret = copy_from_kernel_nofault(insn, ip, size);
        if (ret)
                return ret;

        for (i = 0; i < size / 4; i++) {
                if (insn[i] != INSN_NOP)
                        return -EINVAL;
        }

        __patch_text_multiple(ip, tramp, size);
        return 0;
}

int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
                    unsigned long addr)
{
        u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
        int i;

        for (i = 0; i < ARRAY_SIZE(insn); i++)
                insn[i] = INSN_NOP;

        __patch_text((void *)rec->ip, INSN_NOP);
        __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
                              insn, sizeof(insn)-4);
        return 0;
}
#endif

#ifdef CONFIG_KPROBES_ON_FTRACE
void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
                           struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
        struct kprobe_ctlblk *kcb;
        struct pt_regs *regs;
        struct kprobe *p;
        int bit;

        if (unlikely(kprobe_ftrace_disabled))
                return;

        bit = ftrace_test_recursion_trylock(ip, parent_ip);
        if (bit < 0)
                return;

        regs = ftrace_get_regs(fregs);
        p = get_kprobe((kprobe_opcode_t *)ip);
        if (unlikely(!p) || kprobe_disabled(p))
                goto out;

        if (kprobe_running()) {
                kprobes_inc_nmissed_count(p);
                goto out;
        }

        __this_cpu_write(current_kprobe, p);

        kcb = get_kprobe_ctlblk();
        kcb->kprobe_status = KPROBE_HIT_ACTIVE;

        regs->iaoq[0] = ip;
        regs->iaoq[1] = ip + 4;

        if (!p->pre_handler || !p->pre_handler(p, regs)) {
                regs->iaoq[0] = ip + 4;
                regs->iaoq[1] = ip + 8;

                if (unlikely(p->post_handler)) {
                        kcb->kprobe_status = KPROBE_HIT_SSDONE;
                        p->post_handler(p, regs, 0);
                }
        }
        __this_cpu_write(current_kprobe, NULL);
out:
        ftrace_test_recursion_unlock(bit);
}
NOKPROBE_SYMBOL(kprobe_ftrace_handler);

int arch_prepare_kprobe_ftrace(struct kprobe *p)
{
        p->ainsn.insn = NULL;
        return 0;
}
#endif