UASM 2.57

[johnsa]

I think shared libraries depend on PLT and GOT - much like PIE executables, neither of which are supported - and for years there has been no clear or logical way to support them.

Without a HLL language/compiler to infer the plt/got stuff I've not seen any assembler actually solve this.
YASM had something - but it's dead and never worked right, I don't know the state of NASM in this regard, there was a whole bunch of awful filth about using ..wrt operator.

I don't really work on Linux so I'm no expert, but happy for someone to help try and solve things - as far as I can tell from my albeit limited perspective, Linux is a piece of sh1t and designed by C programmers who clearly hate assembly language. :)

[mineiro]

I'm not a C programmer, so I can't help in this sense.
My investigation tolds me that if a shared library don't use internally a call to an external function that exist in a library, so that works fine. The main problem that I faced was when calling an external function that exist in a library.

native.asm

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;not modified uasm without calling a function in an external library
;uasm -elf64 -pie native.asm
;ld --no-dynamic-linker -pie -e _start -o native native.o

;or using plugin.o from previous post
;uasm -elf64 -pie native.asm
;gcc -shared -o libplugin.so plugin.o native.o

.x64
.data
hello db "hello",10,0


.code
public _start
_start:
public quit
quit:

    mov rax,1
    mov rdi,1
    lea rsi,hello
    mov rdx,sizeof hello
    syscall

    mov rax,60
    mov rdi,0
    syscall


;end _start
end

Position independent code is working in my tests too (with modified uasm from previous post).
pie.asm

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;modified uasm
;uasm -elf64 pie.asm
;gcc -lc -pie pie.o -o pie

.X64
option casemap:none

printf proto :vararg
exit proto :dword

.code
public main
main proc uses r12 argc:dword, argv:ptr
; call @F
;@@:
; pop r12
; sub r12,$-main

lea r12,main
invoke printf,CStr("%016llx",10),r12
    invoke exit,0
main endp

end main

results from program above run multiple times (checked with debugger too):
./pie
0000555841760150
000055e0f34cc150
00005591c59ca150
...

edited: lea r12, main
I was thinking in a switch in uasm command line to elf64, that description is something like "use R_X86_64_PLT32 instead of R_X86_64_PC32".

[tenkey]

PROC directive appears to be broken. It doesn't list the PROC line and affects the following line.

Example:

The original source:

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xWinMain PROC

invoke DialogBoxIndirectParam, InstanceHandle, addr TheDialogTemplate, NULL, addr TheDialogProc, NULL

XOR EAX, EAX
The listing:

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00000031                    00000031  4883EC08          *   sub rsp, 8
          invoke __im00000035                    nstanceHandle, addr TheDialogTemplate, NULL, addr TheDialogProc, NULL
0000002D                    *   sub rsp, 48
00000035  4883EC30           *    mov rcx, In00000039  488B0D00000000                  *    lea rdx, Th00000040  488D1500000000                     *    xor r8d, r800000047  4533C0               *    lea r9, The0000004A  4C8D0D00000000                *    mov qword p00000051  48C744242000000000                   *    call __imp_0000005A  FF1500000000      00059                    *    add rsp, 48000000000064  33C0                  XOR EAX, EAX
The command line:

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uasm -win64 -Fl -Sg -Sn GOL.asm
One file, several examples: You cannot view this attachment.