98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <syscall.h>
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#include <stdio.h>
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static uint32_t mTableStore[(sizeof(struct SyscallTable) + sizeof(union SyscallTableEntry[1 << SYSCALL_BITS_LEVEL_0]) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
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static const uint8_t mLevelBits[] = {SYSCALL_BITS_LEVEL_0, SYSCALL_BITS_LEVEL_1, SYSCALL_BITS_LEVEL_2, SYSCALL_BITS_LEVEL_3, 0};
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static struct SyscallTable *mTable = (struct SyscallTable*)mTableStore;
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void syscallInit(void)
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{
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mTable->numEntries = 1 << SYSCALL_BITS_LEVEL_0;
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}
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bool syscallAddTable(uint32_t path, uint32_t level, struct SyscallTable *table)
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{
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struct SyscallTable** tabP = &mTable;
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const uint8_t *bits = mLevelBits;
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while (level--) {
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uint32_t idx = path >> (32 - *bits);
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path <<= *bits++;
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//cannot traverse
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if ((*tabP)->numEntries <= idx)
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return false;
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//cannot add table as final leaf
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if (*bits == 0)
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return false;
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tabP = &(*tabP)->entry[idx].subtable;
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}
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*tabP = table;
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return true;
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}
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static SyscallFunc* syscallFindHandlerLoc(uint32_t path)
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{
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struct SyscallTable* tab = mTable;
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const uint8_t *bits = mLevelBits;
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while (tab) {
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uint32_t idx = path >> (32 - *bits);
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path <<= *bits++;
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if (tab->numEntries <= idx)
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break;
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if (!*bits)
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return &tab->entry[idx].func;
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else
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tab = tab->entry[idx].subtable;
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}
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return NULL;
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}
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bool syscallAddFunc(uint32_t path, SyscallFunc func)
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{
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SyscallFunc *f = syscallFindHandlerLoc(path);
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if (!f)
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return false;
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*f = func;
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return true;
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}
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SyscallFunc syscallGetHandler(uint32_t path)
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{
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SyscallFunc *f = syscallFindHandlerLoc(path);
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return f ? *f : NULL;
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}
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