32-bit x86: Local Executable (LE)

This code sequence implements the LE model described in Thread-Local Storage Access Models.

0x00 movl  %gs:0, %eax
0x06 leal  x@ntpoff(%eax), %eax

# %eax - contains address of TLS variable

<none>
R_386_TLS_LE

 
x

The movl instruction generates a R_386_TLS_LE_32 relocation. The link-editor binds this relocation directly to the static TLS offset for the symbol defined in the executable. No processing is required at runtime.

The contents of variable x, rather then the address, can be accessed with the same relocation by using the following instruction sequence.

0x00 movl  %gs:0, %eax
0x06 movl  x@ntpoff(%eax), %eax

# %eax - contains address of TLS variable

<none>
R_386_TLS_LE

 
x

Rather than computing the address of the variable, a load from the variable or store to the variable can be accomplished using the following sequence. Note, the x@ntpoff expression is not used as an immediate value, but as an absolute address.

0x00 movl %gs:x@ntpoff, %eax

# %eax - contains address of TLS variable

R_386_TLS_LE

x