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Index > Linux > Get high resolution sys_time

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rCX



Joined: 29 Jul 2007
Posts: 169
Location: Maryland, USA
rCX
I saw that the linux system time in seconds can be obtained using

Code:
mov  eax, 13
xor  ebx, ebx
int  80h ; return system time in seconds in eax
    



Is there a way to obtain the time at a higher resolution e.g milliseconds?
Post 12 Jul 2021, 02:11
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 18109
Location: In your JS exploiting you and your system
revolution
There is GETTIME
Code:
SYS_CLOCK_GETTIME       = 265
CLOCK_MONOTONIC         = 1

struc timespec {
        .tv_sec         rd 1
        .tv_nsec        rd 1
}

time timespec

        mov     ecx,time
        mov     ebx,CLOCK_MONOTONIC
        mov     eax,SYS_CLOCK_GETTIME
        syscall ; or int 0x80    
Post 12 Jul 2021, 07:08
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redsock



Joined: 09 Oct 2009
Posts: 371
Location: Australia
redsock
This is also exposed via the vDSO for syscall-free gettimeofday operation, which provides microsecond resolution.
Code:
man 7 vdso    
for that and clock_gettime which can provide higher resolution still.

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Post 12 Jul 2021, 20:45
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