On Sat, Nov 12, 2016 at 08:55:14PM +0000, Matt Fleming wrote: > On Mon, 07 Nov, at 12:17:00PM, Lukas Wunner wrote: > > Demonstrate the code reduction attainable by efi_call_proto() > > which was proffered in a patch I've posted a few minutes ago. > > > > For this to work, all three protocol variants (_32_t and _64_t for x86 > > and _t for ARM) need to be declared as typedefs. The declaration and > > naming of protocols in include/linux/efi.h currently isn't consistent, > > some are declared as typedefs and some aren't, some use a "_t" suffix > > and some don't. These inconsistencies need to be straightened out > > when converting to efi_call_proto(). It should be noted that checkpatch > > complains about newly introduced typedefs. It would be possible to > > retool efi_call_proto() to work without typedef declarations as long > > as it's done consistently. > > This is probably v4.11 material. We *may* be able to get this into > v4.10 if I review and merge this soon, but it definitely isn't going > to be included in the imminent pull request. > > I do like the general idea though. Yes, this was posted quite late in the cycle so I didn't expect it to make it into 4.10 really. It was meant as a demonstration, I can respin this into a series that deduplicates these redundancies more thoroughly, but I wanted to gauge the reaction of the community first. Ard should probably also weigh in since it touches ARM code. By the way, you mentioned that you have a MacBook2,1, is this the Late 2006 version and would you be able to test changes to the efistub on that machine? I was thinking about obtaining such a machine myself on ebay since right now I can only test x86_64, not mixed mode. If noone else is able to perform tests I might just do that. (Only the Late 2006 version uses mixed mode, the Mid 2007 has a native 64-bit EFI.) > > In __file_size32() all protocol calls are currently cast to unsigned long, > > which is 64 bit when compiled on x86_64. Matt has said that the register > > needs to be loaded with a 32 bit address, so it looks to me like this is > > currently broken for mixed-mode. Patch [1/2] should fix this. E.g.: > > > > efi_file_handle_32_t *h, *fh = __fh; > > [...] > > status = efi_early->call((unsigned long)h->get_info, h, &info_guid, > > &info_sz, NULL); > > There's a subtle distinction here between 32-bit address and 32-bit > value. A 64-bit value can be a valid 32-bit address, provided that the > upper 32-bits are zero, e.g. 0x00000000ffffffff. > > So when I say "32-bit address" I really just mean some value where > only the lower 32-bits are important. > > That is why using unsigned long in mixed-mode is OK for the early call > code. > > > Another oddity is that info_sz is declared u32 in __file_size32(), > > yet the spec says that the third argument to EFI_FILE_PROTOCOL.GetInfo() > > is of type UINTN, which I assume is 64 bit regardless of mixed-mode, > > or am I missing something? Patch [1/2] uses an unsigned long instead. > > UINTN is an unsigned value of native width as seen by the firmware. On > 32-bit firmware that's 32-bits and 64-bit firmware 64-bits. > > Using 'u32' in __file_size32() is correct, unsigned long is not. Okay since this is all little endian, it should be okay to have a 64 bit wide variable on the stack whose address is passed to GetInfo() as BufferSize argument. But I guess I need to initialize it to 0 upon declaration so that the upper 32 bit are zeroed out in mixed mode, right? That would be a bug in patch [1/2] then. Thanks, Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
