What's wrong with this code:
includelib msvcrt.lib
includelib ucrt.lib
includelib libucrt.lib
includelib user32.lib
includelib kernel32.lib
extrn system :proc
extrn puts :proc
extrn printf :proc
extrn ExitProcess :proc
.data
string_title_x64_printf db "title x64 printf",0
string_color_0F db "color 0F",0
string_pause db "pause",0
string db "string",0
string_pd_newline db "%d",10,0
.code
main proc c
lea rcx, string_title_x64_printf
call system
lea rcx, string_color_0F
call system
lea rcx, string
call puts
lea rcx, string_pd_newline
mov rdx, 3
call printf
lea rcx, string_pause
call system
call ExitProcess
main endp
endThis exception is thrown:
QuoteUnhandled exception at 0x0000000077528F24 (ntdll.dll) in x64 printf.exe: 0xC0000005: Access violation writing location 0x0000000000000024.
Note that I am running this x64 code in Visual Studio 2015 Enterprise.
Works for me, but with some modifications, see attached project. Where exactly does it crash? What do you see in the debugger?
Quote from: jj2007 on December 24, 2016, 09:05:50 AM
Works for me, but with some modifications, see attached project. Where exactly does it crash? What do you see in the debugger?
It crashes on line/instruction: "call printf".
In the debugger I see the exception, which I already quoted in the question and I will quote it again:
QuoteUnhandled exception at 0x0000000077528F24 (ntdll.dll) in x64 printf.exe: 0xC0000005: Access violation writing location 0x0000000000000024.
And I don't have the requirements of your modifications. Visual Studio 2015 Enterprise doesn't come with include files (.inc files) for masm at all!
Quote from: assembler on December 24, 2016, 09:52:00 AMIt crashes on line/instruction: "call printf".
Interesting.
lea rcx, string_pd_newline
mov rdx, 11111
call printf
lea rcx, string_pd_newline
mov rdx, 22222
jinvoke crt_printf, @
jinvoke crt_printf, addr string_pd_newline, 33333All three variants work, output is ...
11111
22222
33333... as expected, no exceptions here 8)
QuoteUnhandled exception at 0x0000000077528F24 (ntdll.dll) in x64 printf.exe: 0xC0000005: Access violation writing location 0x0000000000000024.
I think the problem in Stack Alignement, Check out Frame Prologue
Unlikely: Access violation writing location 0x0000000000000024
Doesn't look like a stack alignment problem...
One of the thing I learnt when first doing research on x64 with ML64 was that if you want to use high level code (c runtime etc..) you must construct a stack frame that is aligned correctly. For pure mnemonic code, you don't need a stack frame.
JJ is correct here, if you are getting a page fault from OFFSET 24, you have an addressing error in you code somewhere. Sounds like a null pointer with an added offset.
Quote from: jj2007 on December 24, 2016, 12:29:06 PM
Unlikely: Access violation writing location 0x0000000000000024
Doesn't look like a stack alignment problem...
you are right JJ, thank you
the code worked properly without
ucrt.lib and
libucrt.lib
includelib msvcrt.lib
;includelib ucrt.lib
;includelib libucrt.lib
;includelib user32.lib
includelib kernel32.lib
extrn system :proc
extrn puts :proc
extrn printf :proc
extrn ExitProcess :proc
.data
string_title_x64_printf db "title x64 printf",0
string_color_0F db "color 0F",0
string_pause db "pause",0
string db "string",0
string_pd_newline db "%d",10,0
.code
main proc c
lea rcx, string_title_x64_printf
call system
lea rcx, string_color_0F
call system
lea rcx, string
call puts
lea rcx, string_pd_newline
mov rdx, 3
call printf
lea rcx, string_pause
call system
call ExitProcess
main endp
end
Shadow space created with the sub command :
includelib msvcrt.lib
includelib kernel32.lib
EXTRN system:PROC
EXTRN puts:PROC
EXTRN printf:PROC
EXTRN ExitProcess:PROC
.data
string_title_x64_printf db "title x64 printf",0
string_color_0F db "color 0F",0
string_pause db "pause",0
string db "string",0
string_pd_newline db "%d",10,0
.code
mainCRTStartup PROC C
sub rsp,4*8
lea rcx, string_title_x64_printf
call system
lea rcx, string_color_0F
call system
lea rcx, string
call puts
lea rcx, string_pd_newline
mov rdx, 3
call printf
lea rcx, string_pause
call system
call ExitProcess
ret
mainCRTStartup ENDP
END
sub rsp,4*8
Don't you need another 8? The entry is aligned 8, not 16, unless C does things differently?
Hi sinsi,
The statement mainCRTStartup PROC C creates a stack frame. Disassembling the object module with Agner Fog's objconv :
mainCRTStartup PROC
push rbp
mov rbp, rsp
sub rsp, 32
lea rcx, ptr [string_title_x64_printf]
call system
lea rcx, ptr [string_color_0F]
call system
lea rcx, ptr [string]
call puts
lea rcx, ptr [string_pd_newline]
mov rdx, 3
call printf
lea rcx, ptr [string_pause]
call system
call ExitProcess
leave
ret
mainCRTStartup ENDP
What msvc 2015 in C do?void __declspec(noreturn) ExitProcess(int);
#pragma comment(lib, "kernel32.lib")
int system(const char *string);
int puts(const char *string);
int printf(const char *format, ...);
#pragma comment(lib, "msvcrt.lib")
char *string_title_x64_printf = "title x64 printf";
char *string_color_0F = "color 0F";
char *string_pause = "pause";
char *string = "string";
char *string_pd_newline = "%d\n";
void mainCRTStartup(void)
{
system(string_title_x64_printf);
system(string_color_0F);
puts(string);
printf(string_pd_newline, 3);
system(string_pause);
ExitProcess(0);
}mainCRTStartup:
sub rsp,28h
mov rcx,qword ptr [string_title_x64_printf]
call system
mov rcx,qword ptr [string_color_0F]
call system
mov rcx,qword ptr [string]
call puts
mov rcx,qword ptr [string_pd_newline]
mov edx,3
call printf
mov rcx,qword ptr [string_pause]
call system
xor ecx,ecx
call ExitProcess
and ml64.exemainCRTStartup:
push rbp
mov rbp,rsp
lea rcx,[string_title_x64_printf]
call system
lea rcx,[string_color_0F]
call system
lea rcx,[string]
call puts
lea rcx,[string_pd_newline]
mov rdx,3
call printf
lea rcx,[string_pause]
call system
call ExitProcess
leave
ret
Quote from: Vortex on December 24, 2016, 08:46:39 PM
The statement mainCRTStartup PROC C creates a stack frame.
:t
I'm almost sure the problem is in MS VS
Try assembling your project from command line