Why linux kernel use trap gate to handle divide_error exception?

In kernel 2.6.11.5, divide zero exception handler is set up as:

set_trap_gate(0,&divide_error);

According to "Understanding The Linux Kernel", Intel trap gate cannot be accessed by a User Mode process. But it's quite possible that a user mode process also generate a divide_error. So why Linux implement it in this way?

[Edit] I think that the question is still open, since set_trap_gate() sets DPL value of IDT entry to 0, which means only CPL=0 (read kernel) code can execute it, so it's unclear to me how this handler may be called from the user mode:

#include<stdio.h>

int main(void)
{
    int a = 0;
    int b = 1;

    b = b/a;

    return b;
}

which was compiled with gcc div0.c. And the output of ./a.out is:

Floating point exception (core dumped)

So it doesn't look like this was handled by the division by 0 trap code.