* syscall descriptor table
@ 2012-04-05 21:55 Xin Tong
2012-04-06 8:24 ` Jiri Slaby
0 siblings, 1 reply; 2+ messages in thread
From: Xin Tong @ 2012-04-05 21:55 UTC (permalink / raw)
To: linux-kernel
Can anyone please describe to me how x86 syscall works ( i.e. how it
is dispatched to the correct function) on x86 ?
mov $1, %eax ;; __NR_exit = 1
mov $42, %ebx ;; status = 42
sysenter ;; perform the syscall!
what does the sysenter instruction do ? what is the difference aganst int 0x80.
Thanks
Xin
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: syscall descriptor table
2012-04-05 21:55 syscall descriptor table Xin Tong
@ 2012-04-06 8:24 ` Jiri Slaby
0 siblings, 0 replies; 2+ messages in thread
From: Jiri Slaby @ 2012-04-06 8:24 UTC (permalink / raw)
To: Xin Tong; +Cc: linux-kernel, Jiri Slaby
On 04/05/2012 11:55 PM, Xin Tong wrote:
> Can anyone please describe to me how x86 syscall works ( i.e. how it
> is dispatched to the correct function) on x86 ?
>
> mov $1, %eax ;; __NR_exit = 1
> mov $42, %ebx ;; status = 42
> sysenter ;; perform the syscall!
>
> what does the sysenter instruction do ? what is the difference aganst int 0x80.
Please refer to some processor manual. For example: Intel 64 and IA-32
Architectures Software Developer’s Manual. For the entry point see
ia32_sysenter_target in arch/x86/kernel/entry_32.S for x86_32 or
arch/x86/ia32/ia32entry.S for x86_64 with 32-bit binary.
regards,
--
js
suse labs
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