> On 4 Jul 2016, at 20:27, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > > On July 4, 2016 6:52:58 AM PDT, "Tautschnig, Michael" <tautschn@xxxxxxxxxxxx> wrote: >> All syscall arguments are passed in as types of the same byte size as >> unsigned long (width of full registers). Using a smaller type without a >> cast may result in losing bits of information. In all other instances >> apart from the ones fixed by the patch the code explicitly introduces >> type casts (using, e.g., SYSCALL_DEFINE1). >> >> While goto-cc reported these problems at build time, it is noteworthy >> that the calling conventions specified in the System V AMD64 ABI do >> ensure that parameters 1-6 are passed via registers, thus there is no >> implied risk of misaligned stack access. >> >> [...] > > Wrong. Syscall arguments aren't necessarily full registers, and on x86 truncation is already done by the callee, so we don't need any special handing. Some other architectures have other constraints. Ok - I'm assuming I have thus misunderstood eb974c62565072e10c1422eb3205f5b611dd99a1 ? Supposedly all those SYSCALL_DEFINEx are required for other architectures only? Best, Michael -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
