Difference between revisions of "Assembler:Commands:JMP"

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Line 2: Line 2:
  
 
Jumps to the given operand (address).
 
Jumps to the given operand (address).
 +
 +
Transfers program control to a different point in the instruction stream without recording return information.
 +
The destination (target) operand specifies the address of the instruction being jumped to.
 +
This operand can be an immediate value, a general-purpose register, or a memory location.
 +
 +
This instruction can be used to execute four different types of jumps:
 +
; Near jump
 +
: A jump to an instruction within the current code segment (the segment currently pointed to by the CS register), sometimes referred to as an intrasegment jump.
 +
; Short jump
 +
: A near jump where the jump range is limited to -128 to +127 from the current EIP value.
 +
; Far jump
 +
: A jump to an instruction located in a different segment than the current code segment but at the same privilege level, sometimes referred to as an intersegment jump.
 +
; Task switch
 +
: A jump to an instruction located in a different task.
  
 
=== Command Parameters ===
 
=== Command Parameters ===
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  jmp @f  // Jump forward to closest label
 
  jmp @f  // Jump forward to closest label
 +
 +
 +
Running this script in 32 bit mode:
 +
globalAlloc(memTest, 0x200)
 +
label(testLbl)
 +
memTest:
 +
                          add [eax],al // db 00 00
 +
@@:
 +
                          add [eax],al
 +
jmp short @b
 +
jmp short @f
 +
                          add [eax],al
 +
@@:
 +
                          add [eax],al
 +
                          add [eax],al
 +
jmp short -4
 +
jmp short +2
 +
                          add [eax],al
 +
testLbl:
 +
                          add [eax],al
 +
jmp 02EA0002
 +
                          add [eax],al
 +
jmp eax
 +
                          add [eax],al
 +
jmp memTest
 +
                          add [eax],al
 +
jmp testLbl
 +
                          add [eax],al
 +
jmp short testLbl
 +
                          add [eax],al
 +
jmp long testLbl
 +
                          add [eax],al
 +
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
 +
 +
[[File:Assembler.JMP.02.png]]
  
  
Line 73: Line 122:
  
 
[[File:Assembler.JMP.01.png]]
 
[[File:Assembler.JMP.01.png]]
 +
  
 
== See also ==
 
== See also ==
Line 78: Line 128:
 
* [[Cheat_Engine:Auto Assembler|Auto Assembler]]
 
* [[Cheat_Engine:Auto Assembler|Auto Assembler]]
 
* [[Assembler:Commands|Assembler Commands]]
 
* [[Assembler:Commands|Assembler Commands]]
 +
 +
* [http://x86.renejeschke.de/html/file_module_x86_id_147.html x86.renejeschke.de/html/file_module_x86_id_147.html]
  
 
== External links ==
 
== External links ==
 
* [https://wikipedia.org/wiki/X86_instruction_listings wikipedia.org/wiki/X86_instruction_listings]
 
* [https://wikipedia.org/wiki/X86_instruction_listings wikipedia.org/wiki/X86_instruction_listings]
 +
* [https://wikibooks.org/wiki/X86_Assembly/Other_Instructions wikibooks.org/wiki/X86_Assembly/Other_Instructions]
 
* [http://www.asmpedia.org/index.php?title=Main_Page asmpedia.org]
 
* [http://www.asmpedia.org/index.php?title=Main_Page asmpedia.org]

Revision as of 02:30, 14 March 2017

command jmp size operand

Jumps to the given operand (address).

Transfers program control to a different point in the instruction stream without recording return information. The destination (target) operand specifies the address of the instruction being jumped to. This operand can be an immediate value, a general-purpose register, or a memory location.

This instruction can be used to execute four different types of jumps:

Near jump
A jump to an instruction within the current code segment (the segment currently pointed to by the CS register), sometimes referred to as an intrasegment jump.
Short jump
A near jump where the jump range is limited to -128 to +127 from the current EIP value.
Far jump
A jump to an instruction located in a different segment than the current code segment but at the same privilege level, sometimes referred to as an intersegment jump.
Task switch
A jump to an instruction located in a different task.

Command Parameters

Parameter Description
size OPTIONAL The preferred size of the assembled address
operand The address or symbol to jump to


Examples

jmp +1A   // Jump from end of command to +1A (hex).
jmp 00123ABC   // Jump to address.
jmp 0000123456ABCDEF   // Jump to address.
jmp eax   // Jump to value of eax.
jmp rax   // Jump to value of rax.
jmp someSymbol   // Jump to user defined symbol.
jmp someLabel   // Jump to label.
jmp short someLabel   // Jump to label with short byte code.
jmp long someLabel   // Jump to label with full address.
jmp @b   // Jump back to closest label
jmp @f   // Jump forward to closest label


Running this script in 32 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [eax],al // db 00 00
@@:
                          add [eax],al
jmp short @b
jmp short @f
                          add [eax],al
@@:
                          add [eax],al
                          add [eax],al
jmp short -4
jmp short +2
                          add [eax],al
testLbl:
                          add [eax],al
jmp 02EA0002
                          add [eax],al
jmp eax
                          add [eax],al
jmp memTest
                          add [eax],al
jmp testLbl
                          add [eax],al
jmp short testLbl
                          add [eax],al
jmp long testLbl
                          add [eax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

Assembler.JMP.02.png


Running this script in 64 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [rax],al // db 00 00
@@:
                          add [rax],al
jmp short @b
jmp short @f
                          add [rax],al
@@:
                          add [rax],al
                          add [rax],al
jmp short -4
jmp short +2
                          add [rax],al
testLbl:
                          add [rax],al
jmp 01160002
                          add [rax],al
jmp rax
                          add [rax],al
jmp memTest
                          add [rax],al
jmp testLbl
                          add [rax],al
jmp short testLbl
                          add [rax],al
jmp long testLbl
                          add [rax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

Assembler.JMP.01.png


See also

External links