| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
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| 3 | //
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| 4 | // The contents of this file are covered under the licence agreement in the
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| 5 | // file "LICENCE" distributed with Cforall.
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| 6 | //
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| 7 | // CtxSwitch-x86_64.S --
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| 8 | //
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| 9 | // Author           : Peter A. Buhr
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| 10 | // Created On       : Mon Aug 10 08:10:26 2020
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| 11 | // Last Modified By : Peter A. Buhr
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| 12 | // Last Modified On : Sat Oct 24 14:36:25 2020
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| 13 | // Update Count     : 10
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| 14 | //
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| 15 | 
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| 16 | // The context switch routine requires the initial the stack of a thread to
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| 17 | // look like the thread has saved its context in the normal manner.
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| 18 | 
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| 19 | // Offsets must synchronized with the __stack_context_t in invoke.h.
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| 20 | 
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| 21 | #define PTR_BYTE        8
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| 22 | #define SP_OFFSET       ( 0 * PTR_BYTE )
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| 23 | #define FP_OFFSET       ( 1 * PTR_BYTE )
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| 24 | 
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| 25 | // Context switch between coroutines/tasks.
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| 26 | //   void __cfactx_switch( struct __stack_context_t * from, struct __stack_context_t * to ) ;
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| 27 | // Arguments "from" in register rdi, "to" in register rsi.
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| 28 | 
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| 29 |         .file "CtxSwitch-x86_64.S"
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| 30 |         .text
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| 31 |         .align 2
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| 32 |         .global __cfactx_switch
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| 33 |         .type __cfactx_switch, @function
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| 34 | __cfactx_switch:
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| 35 | 
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| 36 |         // Save volatile registers on the stack.
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| 37 | 
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| 38 |         pushq %r15
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| 39 |         pushq %r14
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| 40 |         pushq %r13
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| 41 |         pushq %r12
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| 42 |         pushq %rbx
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| 43 | 
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| 44 |         // Save old context in the "from" area.
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| 45 | 
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| 46 |         movq %rsp,SP_OFFSET(%rdi)
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| 47 |         movq %rbp,FP_OFFSET(%rdi)
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| 48 | 
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| 49 |         // Load new context from the "to" area.
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| 50 | 
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| 51 |         movq SP_OFFSET(%rsi),%rsp
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| 52 |         movq FP_OFFSET(%rsi),%rbp
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| 53 | 
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| 54 |         // Load volatile registers from the stack.
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| 55 | 
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| 56 |         popq %rbx
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| 57 |         popq %r12
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| 58 |         popq %r13
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| 59 |         popq %r14
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| 60 |         popq %r15
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| 61 | 
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| 62 |         // Return to thread.
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| 63 | 
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| 64 |         ret
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| 65 |         .size __cfactx_switch, .-__cfactx_switch
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| 66 | 
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| 67 | // Stub to create new stacks which can be context switched to
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| 68 | //   void __cfactx_invoke_stub( void );
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| 69 | 
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| 70 |         .text
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| 71 |         .align 2
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| 72 |         .global __cfactx_invoke_stub
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| 73 |         .type __cfactx_invoke_stub, @function
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| 74 | __cfactx_invoke_stub:
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| 75 |         movq %rbx, %rdi                                         // move main and this to first two arguments
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| 76 |         movq %r12, %rsi
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| 77 |         jmp *%r13                                                       // jmp to invoke
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| 78 |         .size __cfactx_invoke_stub, .-__cfactx_invoke_stub
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| 79 | 
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| 80 | // Local Variables: //
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| 81 | // mode: asm //
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| 82 | // tab-width: 4 //
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| 83 | // End: //
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