On 12/14/20 3:37 AM, Huacai Chen wrote: > Hi, Philippe, > > On Mon, Dec 14, 2020 at 7:09 AM Philippe Mathieu-Daudé <f4...@amsat.org> > wrote: >> >> On 12/13/20 11:17 PM, Philippe Mathieu-Daudé wrote: >>> On 12/11/20 12:32 PM, Philippe Mathieu-Daudé wrote: >>>> On 12/11/20 3:46 AM, Huacai Chen wrote: >>>>> Hi, Rechard and Peter, >>>>> >>>>> On Wed, Dec 2, 2020 at 5:32 PM Philippe Mathieu-Daudé <f4...@amsat.org> >>>>> wrote: >>>>>> >>>>>> On 12/2/20 2:14 AM, Huacai Chen wrote: >>>>>>> Hi, Phillippe, >>>>>>> >>>>>>> On Tue, Nov 24, 2020 at 6:25 AM Philippe Mathieu-Daudé >>>>>>> <f4...@amsat.org> wrote: >>>>>>>> >>>>>>>> On 11/6/20 5:21 AM, Huacai Chen wrote: >>>>>>>>> Preparing to add Loongson-3 machine support, add Loongson-3's LEFI (a >>>>>>>>> UEFI-like interface for BIOS-Kernel boot parameters) helpers first. >>>>>>>>> >>>>>>>>> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> >>>>>>>>> Signed-off-by: Huacai Chen <che...@lemote.com> >>>>>>>>> Co-developed-by: Jiaxun Yang <jiaxun.y...@flygoat.com> >>>>>>>>> Signed-off-by: Jiaxun Yang <jiaxun.y...@flygoat.com> >>>>>>>>> --- >>>>>>>>> hw/mips/loongson3_bootp.c | 165 +++++++++++++++++++++++++++++++ >>>>>>>>> hw/mips/loongson3_bootp.h | 241 >>>>>>>>> ++++++++++++++++++++++++++++++++++++++++++++++ >>>>>>>>> hw/mips/meson.build | 1 + >>>>>>>>> 3 files changed, 407 insertions(+) >>>>>>>>> create mode 100644 hw/mips/loongson3_bootp.c >>>>>>>>> create mode 100644 hw/mips/loongson3_bootp.h >>>>>>>>> >>>>>>>>> diff --git a/hw/mips/loongson3_bootp.c b/hw/mips/loongson3_bootp.c >>>>>>>>> new file mode 100644 >>>>>>>>> index 0000000..3a16081 >>>>>>>>> --- /dev/null >>>>>>>>> +++ b/hw/mips/loongson3_bootp.c >>>>>>>>> @@ -0,0 +1,165 @@ >>>>>>>>> +/* >>>>>>>>> + * LEFI (a UEFI-like interface for BIOS-Kernel boot parameters) >>>>>>>>> helpers >>>>>>>>> + * >>>>>>>>> + * Copyright (c) 2018-2020 Huacai Chen (che...@lemote.com) >>>>>>>>> + * Copyright (c) 2018-2020 Jiaxun Yang <jiaxun.y...@flygoat.com> >>>>>>>>> + * >>>>>>>>> + * This program is free software: you can redistribute it and/or >>>>>>>>> modify >>>>>>>>> + * it under the terms of the GNU General Public License as published >>>>>>>>> by >>>>>>>>> + * the Free Software Foundation, either version 2 of the License, or >>>>>>>>> + * (at your option) any later version. >>>>>>>>> + * >>>>>>>>> + * This program is distributed in the hope that it will be useful, >>>>>>>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >>>>>>>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >>>>>>>>> + * GNU General Public License for more details. >>>>>>>>> + * >>>>>>>>> + * You should have received a copy of the GNU General Public License >>>>>>>>> + * along with this program. If not, see >>>>>>>>> <https://www.gnu.org/licenses/>. >>>>>>>>> + */ >>>>>>>>> + >>>>>>>>> +#include "qemu/osdep.h" >>>>>>>>> +#include "qemu/units.h" >>>>>>>>> +#include "qemu/cutils.h" >>>>>>>>> +#include "cpu.h" >>>>>>>>> +#include "hw/boards.h" >>>>>>>>> +#include "hw/mips/loongson3_bootp.h" >>>>>>>>> + >>>>>>>>> +#define LOONGSON3_CORE_PER_NODE 4 >>>>>>>>> + >>>>>>>>> +static struct efi_cpuinfo_loongson *init_cpu_info(void *g_cpuinfo, >>>>>>>>> uint64_t cpu_freq) >>>>>>>>> +{ >>>>>>>>> + struct efi_cpuinfo_loongson *c = g_cpuinfo; >>>>>>>>> + >>>>>>>>> + stl_le_p(&c->cputype, Loongson_3A); >>>>>>>>> + stl_le_p(&c->processor_id, MIPS_CPU(first_cpu)->env.CP0_PRid); >>>>>>>> >>>>>>>> Build failing with Clang: >>>>>>>> >>>>>>>> FAILED: libqemu-mips64el-softmmu.fa.p/hw_mips_loongson3_bootp.c.o >>>>>>>> hw/mips/loongson3_bootp.c:35:15: error: taking address of packed member >>>>>>>> 'processor_id' of class or structure 'efi_cpuinfo_loongson' may result >>>>>>>> in an unaligned pointer value [-Werror,-Waddress-of-packed-member] >>>>>>>> stl_le_p(&c->processor_id, MIPS_CPU(first_cpu)->env.CP0_PRid); >>>>>>>> ^~~~~~~~~~~~~~~ >>>>>>>> 1 error generated. >>>>>>> We cannot reproduce it on X86/MIPS with clang... >>>>>> >>>>>> You can reproduce running the Clang job on Gitlab-CI: >>>>>> >>>>>> https://wiki.qemu.org/Testing/CI/GitLabCI >>>>>> >>>>>>> And I found that >>>>>>> stl_le_p() will be __builtin_memcpy(), I don't think memcpy() will >>>>>>> cause unaligned access. So, any suggestions? >>>> >>>> My understanding is the compiler is complaining for the argument >>>> passed to the caller, with no knowledge of the callee implementation. >>>> >>>> Which makes me wonder if these functions are really inlined... >>>> >>>> Do we need to use QEMU_ALWAYS_INLINE for these LDST helpers? >>> >>> No, this doesn't work neither. >> >> Well, this works: >> >> -- >8 -- >> @@ -32,7 +32,7 @@ static struct efi_cpuinfo_loongson *init_cpu_info(void >> *g_cpuinfo, uint64_t cpu_ >> struct efi_cpuinfo_loongson *c = g_cpuinfo; >> >> stl_le_p(&c->cputype, Loongson_3A); >> - stl_le_p(&c->processor_id, MIPS_CPU(first_cpu)->env.CP0_PRid); >> + c->processor_id = cpu_to_le32(MIPS_CPU(first_cpu)->env.CP0_PRid); >> if (cpu_freq > UINT_MAX) { >> stl_le_p(&c->cpu_clock_freq, UINT_MAX); >> } else { > > This seems not allowed. In include/qemu/bswap.h it says: > * Do an in-place conversion of the value pointed to by @v from the > * native endianness of the host CPU to the specified format. > * > * Both X_to_cpu() and cpu_to_X() perform the same operation; you > * should use whichever one is better documenting of the function your > * code is performing. > * > * Do not use these functions for conversion of values which are in guest > * memory, since the data may not be sufficiently aligned for the host CPU's > * load and store instructions. Instead you should use the ld*_p() and > * st*_p() functions, which perform loads and stores of data of any > * required size and endianness and handle possible misalignment. > > And there is a very strange problem, nearly all 32bit members are > after a 16bit vers member, why only processor_id is special? Compiler > bug?
This is what I wonder since some time but I don't have the knowledge to confirm. Indeed I commented the "stl_le_p(&c->processor_id, ...);" line, and there is no error for the following 32-bit values, which are similarly unlikely 32-bit aligned. FWIW I am using Fedora release 32 (Thirty Two), and 'cc -v': clang version 10.0.1 (Fedora 10.0.1-3.fc32) Target: x86_64-unknown-linux-gnu clang -cc1 version 10.0.1 based upon LLVM 10.0.1 default target x86_64-unknown-linux-gnu > > Huacai >> --- >> >>> >>>> >>>> I see Richard used it in commit 80d9d1c6785 ("cputlb: Split out >>>> load/store_memop"). >>>> >>>>>> >>>>>> I'll defer this question to Richard/Peter who have deeper understanding. >>>>> Any sugguestions? Other patches are updated, except this one. >>>> >>>> Searching on the list, I see Marc-André resolved that by >>>> using a copy on the stack: >>>> https://www.mail-archive.com/qemu-devel@nongnu.org/msg614482.html