| // |
| // Licensed to the Apache Software Foundation (ASF) under one or more |
| // contributor license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright ownership. |
| // The ASF licenses this file to You under the Apache License, Version 2.0 |
| // (the "License"); you may not use this file except in compliance with |
| // the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| .text |
| .align 4 |
| |
| // struct Registers { |
| // uint32 eax; +00 |
| // uint32 ebx; +04 |
| // uint32 ecx; +08 |
| // uint32 edx; +0C |
| // uint32 edi; +10 |
| // uint32 esi; +14 |
| // uint32 ebp; +18 |
| // uint32 esp; +1C |
| // uint32 eip; +20 |
| // uint32 eflags; +24 |
| // }; |
| // |
| // void port_transfer_to_regs(Registers* regs) |
| |
| .globl port_transfer_to_regs |
| .type port_transfer_to_regs, @function |
| port_transfer_to_regs: |
| movl 0x04(%esp), %edx // store regs pointer to EDX |
| movl 0x20(%edx), %ebx // EIP field -> EBX |
| movl 0x1C(%edx), %ecx // ESP field |
| subl $4, %ecx |
| movl %ecx, 0x04(%esp) // (new ESP - 4) -> [ESP + 4] (safe storage) |
| movl 0x14(%edx), %esi // ESI field |
| movl 0x10(%edx), %edi // EDI field |
| movl 0x18(%edx), %ebp // EBP field |
| movl %ebx, (%ecx) // new EIP -> (new ESP - 4) (as return address) |
| movl 0x00(%edx), %eax // EAX field |
| movl 0x04(%edx), %ebx // EBX field |
| movzwl 0x24(%edx), %ecx // (word)EFLAGS -> ECX |
| test %ecx, %ecx |
| je _label_ |
| pushfl |
| andl $0x003F7202, (%esp) |
| andl $0x00000CD5, %ecx |
| orl %ecx, (%esp) |
| popfl // restore EFLAGS |
| _label_: |
| movl 0x08(%edx), %ecx // ECX field |
| movl 0x0C(%edx), %edx // EDX field |
| movl 0x04(%esp), %esp // ((new ESP - 4) -> ESP |
| ret // JMP by RET |
| |
| |
| // void port_longjump_stub(void) |
| // |
| // after returning from the called function, EBP points to the pointer |
| // to saved Registers structure |
| // |
| // | interrupted | |
| // | program | <- ESP where the program was interrupted by signal |
| // |-------------| |
| // | return addr | |
| // | from stub | <- for using in port_transfer_to_regs |
| // |-------------| |
| // | saved | |
| // | Registers | <- to restore register context |
| // |-------------| |
| // | pointer to | |
| // | saved Regs | <- EBP |
| // |-------------| |
| // | arg 5 | <- |
| // |-------------| | |
| // ............... - arguments for 'fn' |
| // |-------------| | |
| // | arg 0 | <- |
| // |-------------| |
| // | return addr | |
| // | from 'fn' | <- address to return to the port_longjump_stub |
| // |-------------| |
| |
| .globl port_longjump_stub |
| .type port_longjump_stub, @function |
| port_longjump_stub: |
| movl %ebp, %esp // ESP now points to the address of saved Registers |
| call port_transfer_to_regs // restore context |
| ret // dummy RET - unreachable |
