On 03/24/2015 07:34 AM, Ingo Molnar wrote: > > * Denys Vlasenko <vda.li...@googlemail.com> wrote: > >> On Mon, Mar 23, 2015 at 9:38 PM, Andy Lutomirski <l...@amacapital.net> wrote: >>> Actually, I want to remove the added comment in the code. I don't see >>> why we should have a specific comment about SS and not about, say, CS, >>> ESP, or anything else. OK? >> >> Ok. > > Might be nice to place a more generic description there, which > registers are expected to be saved by user-space calling in here, etc.
__kernel_vsyscall entry point has the same ABI in any 32-bit vDSO, the good old int 0x80 calling convention: syscall# in eax, params in ebx/ecx/edx/esi/edi/ebp, all registers are preserved by the syscall. (I think we don't guarantee that all flags are preserved: I have a testcase where DF gets cleared). Each flavor of fast kernel call does necessary massaging to conform to the ABI. E.g. SYSCALL-based fast call clobbers ecx, so its vDSO saves/restores ecx on stack. Do you want a patch which adds such comment into every vDSO? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
