1 | // Copyright 2019 The Marl Authors. |
2 | // |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
4 | // you may not use this file except in compliance with the License. |
5 | // You may obtain a copy of the License at |
6 | // |
7 | // https://www.apache.org/licenses/LICENSE-2.0 |
8 | // |
9 | // Unless required by applicable law or agreed to in writing, software |
10 | // distributed under the License is distributed on an "AS IS" BASIS, |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | // See the License for the specific language governing permissions and |
13 | // limitations under the License. |
14 | |
15 | #if defined(__i386__) |
16 | |
17 | #include "osfiber_asm_x86.h" |
18 | |
19 | #include "marl/export.h" |
20 | |
21 | MARL_EXPORT |
22 | void marl_fiber_trampoline(void (*target)(void*), void* arg) { |
23 | target(arg); |
24 | } |
25 | |
26 | MARL_EXPORT |
27 | void marl_fiber_set_target(struct marl_fiber_context* ctx, |
28 | void* stack, |
29 | uint32_t stack_size, |
30 | void (*target)(void*), |
31 | void* arg) { |
32 | // The stack pointer needs to be 16-byte aligned when making a 'call'. |
33 | // The 'call' instruction automatically pushes the return instruction to the |
34 | // stack (4-bytes), before making the jump. |
35 | // The marl_fiber_swap() assembly function does not use 'call', instead it |
36 | // uses 'jmp', so we need to offset the ESP pointer by 4 bytes so that the |
37 | // stack is still 16-byte aligned when the return target is stack-popped by |
38 | // the callee. |
39 | uintptr_t* stack_top = (uintptr_t*)((uint8_t*)(stack) + stack_size); |
40 | ctx->EIP = (uintptr_t)&marl_fiber_trampoline; |
41 | ctx->ESP = (uintptr_t)&stack_top[-5]; |
42 | stack_top[-3] = (uintptr_t)arg; |
43 | stack_top[-4] = (uintptr_t)target; |
44 | stack_top[-5] = 0; // No return target. |
45 | } |
46 | |
47 | #endif // defined(__i386__) |
48 | |