On Friday, January 31, 2020, Alex Bennée <alex.ben...@linaro.org> wrote:
> ** Tags added: tcg testcase > > -- > You received this bug notification because you are a member of qemu- > devel-ml, which is subscribed to QEMU. > https://bugs.launchpad.net/bugs/1861404 > > Title: > AVX instruction VMOVDQU implementation error for YMM registers > > If I remember well, there is no support for AVX instructions in linux-user mode. If that is true, how come handling of unsupported instruction went that far? Did you try other AVX instructions? Aleksandar > Status in QEMU: > New > > Bug description: > Hi, > > Tested with Qemu 4.2.0, and with git version > bddff6f6787c916b0e9d63ef9e4d442114257739. > > The x86 AVX instruction VMOVDQU doesn't work properly with YMM registers > (32 bytes). > It works with XMM registers (16 bytes) though. > > See the attached test case `ymm.c`: when copying from memory-to-ymm0 > and then back from ymm0-to-memory using VMOVDQU, Qemu only copies the > first 16 of the total 32 bytes. > > ``` > user@ubuntu ~/Qemu % gcc -o ymm ymm.c -Wall -Wextra -Werror > > user@ubuntu ~/Qemu % ./ymm > 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 > 18 19 1A 1B 1C 1D 1E 1F > > user@ubuntu ~/Qemu % ./x86_64-linux-user/qemu-x86_64 -cpu max ymm > 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 00 00 00 00 00 00 00 00 > 00 00 00 00 00 00 00 00 > ``` > > This seems to be because in `translate.c > gen_sse()`, the case > handling the VMOVDQU instruction calls `gen_ldo_env_A0` which always > performs a 16 bytes copy using two 8 bytes load and store operations > (with `tcg_gen_qemu_ld_i64` and `tcg_gen_st_i64`). > > Instead, the `gen_ldo_env_A0` function should generate a copy with a > size corresponding to the used register. > > > ``` > static void gen_sse(CPUX86State *env, DisasContext *s, int b, > target_ulong pc_start, int rex_r) > { > [...] > case 0x26f: /* movdqu xmm, ea */ > if (mod != 3) { > gen_lea_modrm(env, s, modrm); > gen_ldo_env_A0(s, offsetof(CPUX86State, xmm_regs[reg])); > } else { > [...] > ``` > > ``` > static inline void gen_ldo_env_A0(DisasContext *s, int offset) > { > int mem_index = s->mem_index; > tcg_gen_qemu_ld_i64(s->tmp1_i64, s->A0, mem_index, MO_LEQ); > tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, > ZMM_Q(0))); > tcg_gen_addi_tl(s->tmp0, s->A0, 8); > tcg_gen_qemu_ld_i64(s->tmp1_i64, s->tmp0, mem_index, MO_LEQ); > tcg_gen_st_i64(s->tmp1_i64, cpu_env, offset + offsetof(ZMMReg, > ZMM_Q(1))); > } > ``` > > To manage notifications about this bug go to: > https://bugs.launchpad.net/qemu/+bug/1861404/+subscriptions > >
