73 lines
2.0 KiB
ArmAsm
73 lines
2.0 KiB
ArmAsm
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; targ-switch.s - Strata contex switch primative operations
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;
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; Copyright (c) 2000, 2004 - Dan Williams and Jack W. Davidson
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;
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;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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section .data
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frag_jmp_addr dd 0
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junk dd 0
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section .text
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extern strata_build_main, hashtable_get_default, intercept_sigaction, syscall_watch_lookup, targ_exec
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BITS32
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global targ_start
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global strata_stop
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global targ_reenter
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; Macros
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; These offsets are based on targ-build.c defines
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; NOTE: the offsets assume 32 bit int, if that changes, these
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; values must change.
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%define STRATA_FROMFRAG(base) [base+106]
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%define STRATA_REDIRECT(base) [base+126]
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%define STRATA_SYSCALL(base) [base+126]
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;; This technically causes a segfault, not an illegal instruction
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;; but I'm unable to find a "standard" illegal instruction for x86
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%define ILLEGAL_INSN mov eax, [0]
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; targ_start -
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; This function is called by by the application immediately after strata_get_start_fn, and it is used to first transfer
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; control from the application to strata. It does this by (basically) doing
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; the same things that occur doing a fragment trampoline.
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targ_start:
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pop eax ; pop the return address, this is the first instruction to execute, and will be passed to s_b_m()
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sub esp, 28 ; this is the code for a trampoline with the next fragment stored in eax, and no from-frag
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push dword [esp]
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pushad
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pushfd
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push dword 0
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push eax
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; We are simulating a call, but we don't want to return here,
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; instead we return to targ_exec
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push targ_exec
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jmp strata_build_main
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; Matainance note: targ_reenter is no
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; longer used. The entire context save
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; has been pushed into the trampoline
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targ_reenter:
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ILLEGAL_INSN
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;
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; see strata_init for details
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;
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; strata_stop - function that returns it's own address so that it can be found w/o writing dynamic linker ickyiness.
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;
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strata_stop:
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call strata_stop_L1
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strata_stop_L1:
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pop eax
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sub eax, 5
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ret
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