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Merge pull request #3493 from Sonicadvance1/bug_for_3478

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unittests/ASM: Implements a unit test for #3478
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Mai 2024-03-13 22:57:39 -04:00 committed by GitHub
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unittests/ASM/FEX_bugs/repeat_stringops_crash.asm Normal file
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%ifdef CONFIG
{
"MemoryRegions": {
"0xf0000000": "4096",
"0xf1000000": "4096"
}
}
%endif
; FEX-Emu had a bug where a backwards repeating string operation would read past the end of a mapped page.
; This was encountered in https://github.com/FEX-Emu/FEX/pull/3478.
; To ensure we don't read past a page with `rep stos` and `rep movs`, map two disparate pages and copy the entire page.
; If FEX tries reading past the ends of either then it will fault.
%macro do_rep_op 2
jmp %%1
%%1:
cld
mov rax, r13
mov rdi, r14
mov rsi, r15
mov rcx, (4096 / %2)
rep %1
%endmacro
%macro do_backward_rep_op 2
jmp %%1
%%1:
std
mov rax, r13
mov rdi, r14
mov rsi, r15
add rdi, (4096 - %2)
add rsi, (4096 - %2)
mov rcx, (4096 / %2)
rep %1
%endmacro
mov r15, 0xf000_0000
mov r14, 0xf100_0000
mov r13, 0x41424344454647
do_rep_op stosb, 1
do_rep_op stosw, 2
do_rep_op stosd, 4
do_rep_op stosq, 8
do_backward_rep_op stosb, 1
do_backward_rep_op stosw, 2
do_backward_rep_op stosd, 4
do_backward_rep_op stosq, 8
do_rep_op movsb, 1
do_rep_op movsw, 2
do_rep_op movsd, 4
do_rep_op movsq, 8
do_backward_rep_op movsb, 1
do_backward_rep_op movsw, 2
do_backward_rep_op movsd, 4
do_backward_rep_op movsq, 8
hlt