Re: Segfault on the i386 enter instruction

[Denis Vlasenko]

On Friday 12 May 2006 16:16, Tomasz Malesinski wrote:
> The code attached below segfaults on the enter instruction. It works
> when a stack frame is created by the three commented out
> instructions and also when the first operand of the enter instruction
> is small (less than about 6500 on my system).
> 
> AFAIK, the only difference between creating a stack frame with the
> enter instruction or push/mov/sub is that enter checks if the new
> value of esp is inside the stack segment limit.
> 
> I tested it on a vanilla kernel 2.4.26 on Intel Celeron and also on
> probably non-vanilla 2.6.16.13 running on 3 dual core AMD Opteron,
> quite busy, server. It is working in 32-bit mode. Interestingly, on
> the second machine sometimes the program worked correctly.

Does not segfault for me:

# gcc Segfault.S

# ./a.out
asdf

# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 11
model name      : Intel(R) Celeron(TM) CPU                1200MHz
stepping        : 1
cpu MHz         : 1196.201
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse
bogomips        : 2395.77

# gcc -v 2>&1 | tail -1
gcc version 3.4.3

--
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