Re: signal dequeue ...

[Davide Libenzi]

On 22-Jun-2001 george anzinger wrote:
> Davide Libenzi wrote:
>> 
>> I'm just trying to figure out the reason why signal must be delivered one at
>> a
>> time instead of building a frame with multiple calls with only the last one
>> chaining back to the kernel.
>> All previous calls instead of calling the stub that jump back to the kernel
>> will call a small stub like ( Ix86 ) :
>> 
>> stkclean_stub:
>>         add $frame_size, %esp
>>         cmp %esp, $end_stubs
>>         jae $sigreturn_stub
>>         ret
>> sigreturn_stub:
>>         mov __NR_sigreturn, %eax
>>         int $0x80
>> end_stubs:
>> 
>> ...
>> | context1
>> * $stkclean_stub
>> * sigh1_eip
>> | context0
>> * $stkclean_stub
>> * sigh0_eip
>> 
>> When sigh0 return, it'll call stkclean_stub that will clean context0 and if
>> we're at the end it'll call the jump-back-to-kernel stub, otherwise the
>> it'll
>> execute the  ret  the will call sigh1 handler ... and so on.
>> 
> And if the user handler does a long_jmp?  

But if the user handler does a long_jump even the old stub will be missed,
isn't it ?

- Davide