On July 4, 2016 1:13:21 PM PDT, "Tautschnig, Michael" <tautschn@xxxxxxxxxxxx> wrote: > >> 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 That, and tracing. -- Sent from my Android device with K-9 Mail. Please excuse brevity and formatting. -- 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
