// SPDX-License-Identifier: GPL-2.0
#include <linux/memory.h>
#include <linux/static_call.h>

#include <asm/text-patching.h>

void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
{
        int err;
        bool is_ret0 = (func == __static_call_return0);
        unsigned long _tramp = (unsigned long)tramp;
        unsigned long _func = (unsigned long)func;
        unsigned long _ret0 = _tramp + PPC_SCT_RET0;
        bool is_short = is_offset_in_branch_range((long)func - (long)(site ? : tramp));

        mutex_lock(&text_mutex);

        if (site && tail) {
                if (!func)
                        err = patch_instruction(site, ppc_inst(PPC_RAW_BLR()));
                else if (is_ret0)
                        err = patch_branch(site, _ret0, 0);
                else if (is_short)
                        err = patch_branch(site, _func, 0);
                else if (tramp)
                        err = patch_branch(site, _tramp, 0);
                else
                        err = 0;
        } else if (site) {
                if (!func)
                        err = patch_instruction(site, ppc_inst(PPC_RAW_NOP()));
                else if (is_ret0)
                        err = patch_instruction(site, ppc_inst(PPC_RAW_LI(_R3, 0)));
                else if (is_short)
                        err = patch_branch(site, _func, BRANCH_SET_LINK);
                else if (tramp)
                        err = patch_branch(site, _tramp, BRANCH_SET_LINK);
                else
                        err = 0;
        } else if (tramp) {
                if (func && !is_short) {
                        err = patch_ulong(tramp + PPC_SCT_DATA, _func);
                        if (err)
                                goto out;
                }

                if (!func)
                        err = patch_instruction(tramp, ppc_inst(PPC_RAW_BLR()));
                else if (is_ret0)
                        err = patch_branch(tramp, _ret0, 0);
                else if (is_short)
                        err = patch_branch(tramp, _func, 0);
                else
                        err = patch_instruction(tramp, ppc_inst(PPC_RAW_NOP()));
        } else {
                err = 0;
        }

out:
        mutex_unlock(&text_mutex);

        if (err)
                panic("%s: patching failed %pS at %pS\n", __func__, func, tramp);
}
EXPORT_SYMBOL_GPL(arch_static_call_transform);