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Re: [RFC v3] linux-user/riscv: Add syscall riscv_hwprobe
From: |
Palmer Dabbelt |
Subject: |
Re: [RFC v3] linux-user/riscv: Add syscall riscv_hwprobe |
Date: |
Thu, 15 Jun 2023 10:12:24 -0700 (PDT) |
On Thu, 08 Jun 2023 00:55:22 PDT (-0700), rehn@rivosinc.com wrote:
> This patch adds the new syscall for the
> "RISC-V Hardware Probing Interface"
> (https://docs.kernel.org/riscv/hwprobe.html).
>
> Signed-off-by: Robbin Ehn <rehn@rivosinc.com>
> ---
> v1->v2: Moved to syscall.c
> v2->v3: Separate function, get/put user
> ---
> linux-user/riscv/syscall32_nr.h | 1 +
> linux-user/riscv/syscall64_nr.h | 1 +
> linux-user/syscall.c | 146 ++++++++++++++++++++++++++++++++
> 3 files changed, 148 insertions(+)
>
> diff --git a/linux-user/riscv/syscall32_nr.h b/linux-user/riscv/syscall32_nr.h
> index 1327d7dffa..412e58e5b2 100644
> --- a/linux-user/riscv/syscall32_nr.h
> +++ b/linux-user/riscv/syscall32_nr.h
> @@ -228,6 +228,7 @@
> #define TARGET_NR_accept4 242
> #define TARGET_NR_arch_specific_syscall 244
> #define TARGET_NR_riscv_flush_icache (TARGET_NR_arch_specific_syscall + 15)
> +#define TARGET_NR_riscv_hwprobe (TARGET_NR_arch_specific_syscall + 14)
> #define TARGET_NR_prlimit64 261
> #define TARGET_NR_fanotify_init 262
> #define TARGET_NR_fanotify_mark 263
> diff --git a/linux-user/riscv/syscall64_nr.h b/linux-user/riscv/syscall64_nr.h
> index 6659751933..29e1eb2075 100644
> --- a/linux-user/riscv/syscall64_nr.h
> +++ b/linux-user/riscv/syscall64_nr.h
> @@ -251,6 +251,7 @@
> #define TARGET_NR_recvmmsg 243
> #define TARGET_NR_arch_specific_syscall 244
> #define TARGET_NR_riscv_flush_icache (TARGET_NR_arch_specific_syscall + 15)
> +#define TARGET_NR_riscv_hwprobe (TARGET_NR_arch_specific_syscall + 14)
> #define TARGET_NR_wait4 260
> #define TARGET_NR_prlimit64 261
> #define TARGET_NR_fanotify_init 262
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 83685f0aa5..e8859cd3be 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -8874,6 +8874,147 @@ static int do_getdents64(abi_long dirfd, abi_long
> arg2, abi_long count)
> }
> #endif /* TARGET_NR_getdents64 */
>
> +#if defined(TARGET_NR_riscv_hwprobe)
> +
> +#define RISCV_HWPROBE_KEY_MVENDORID 0
> +#define RISCV_HWPROBE_KEY_MARCHID 1
> +#define RISCV_HWPROBE_KEY_MIMPID 2
> +
> +#define RISCV_HWPROBE_KEY_BASE_BEHAVIOR 3
> +#define RISCV_HWPROBE_BASE_BEHAVIOR_IMA (1 << 0)
> +
> +#define RISCV_HWPROBE_KEY_IMA_EXT_0 4
> +#define RISCV_HWPROBE_IMA_FD (1 << 0)
> +#define RISCV_HWPROBE_IMA_C (1 << 1)
> +
> +#define RISCV_HWPROBE_KEY_CPUPERF_0 5
> +#define RISCV_HWPROBE_MISALIGNED_UNKNOWN (0 << 0)
> +#define RISCV_HWPROBE_MISALIGNED_EMULATED (1 << 0)
> +#define RISCV_HWPROBE_MISALIGNED_SLOW (2 << 0)
> +#define RISCV_HWPROBE_MISALIGNED_FAST (3 << 0)
> +#define RISCV_HWPROBE_MISALIGNED_UNSUPPORTED (4 << 0)
> +#define RISCV_HWPROBE_MISALIGNED_MASK (7 << 0)
> +
> +struct riscv_hwprobe {
> + abi_llong key;
> + abi_ullong value;
> +};
> +
> +static void risc_hwprobe_fill_pairs(CPURISCVState *env,
> + struct riscv_hwprobe *pair,
> + size_t pair_count)
> +{
> + const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
> +
> + for (; pair_count > 0; pair_count--, pair++) {
> + abi_llong key;
> + abi_ullong value;
> + __put_user(0, &pair->value);
> + __get_user(key, &pair->key);
> + switch (key) {
> + case RISCV_HWPROBE_KEY_MVENDORID:
> + __put_user(cfg->mvendorid, &pair->value);
> + break;
> + case RISCV_HWPROBE_KEY_MARCHID:
> + __put_user(cfg->marchid, &pair->value);
> + break;
> + case RISCV_HWPROBE_KEY_MIMPID:
> + __put_user(cfg->mimpid, &pair->value);
> + break;
> + case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
> + value = riscv_has_ext(env, RVI) &&
> + riscv_has_ext(env, RVM) &&
> + riscv_has_ext(env, RVA) ?
> + RISCV_HWPROBE_BASE_BEHAVIOR_IMA : 0;
> + __put_user(value, &pair->value);
> + break;
> + case RISCV_HWPROBE_KEY_IMA_EXT_0:
> + value = riscv_has_ext(env, RVF) &&
> + riscv_has_ext(env, RVD) ?
> + RISCV_HWPROBE_IMA_FD : 0;
> + value |= riscv_has_ext(env, RVC) ?
> + RISCV_HWPROBE_IMA_C : pair->value;
> + __put_user(value, &pair->value);
> + break;
> + case RISCV_HWPROBE_KEY_CPUPERF_0:
> + __put_user(RISCV_HWPROBE_MISALIGNED_FAST, &pair->value);
> + break;
> + default:
> + __put_user(-1, &pair->key);
> + break;
> + }
> + }
> +}
> +
> +static int cpu_set_valid(abi_long arg3, abi_long arg4)
> +{
> + int ret, i, tmp;
> + size_t host_mask_size, target_mask_size;
> + unsigned long *host_mask;
> +
> + /*
> + * cpu_set_t represent CPU masks as bit masks of type unsigned long *.
> + * arg3 contains the cpu count.
> + */
> + tmp = (8 * sizeof(abi_ulong));
> + target_mask_size = ((arg3 + tmp - 1) / tmp) * sizeof(abi_ulong);
> + host_mask_size = (target_mask_size + (sizeof(*host_mask) - 1)) &
> + ~(sizeof(*host_mask) - 1);
> +
> + host_mask = alloca(host_mask_size);
> +
> + ret = target_to_host_cpu_mask(host_mask, host_mask_size,
> + arg4, target_mask_size);
> + if (ret != 0) {
> + return ret;
> + }
> +
> + for (i = 0 ; i < host_mask_size / sizeof(*host_mask); i++) {
> + if (host_mask[i] != 0) {
> + return 0;
> + }
> + }
> + return -TARGET_EINVAL;
> +}
> +
> +static abi_long do_riscv_hwprobe(CPUArchState *cpu_env, abi_long arg1,
> + abi_long arg2, abi_long arg3,
> + abi_long arg4, abi_long arg5)
> +{
> + int ret;
> + struct riscv_hwprobe *host_pairs;
> +
> + /* flags must be 0 */
> + if (arg5 != 0) {
> + return -TARGET_EINVAL;
> + }
> +
> + /* check cpu_set */
> + if (arg3 != 0) {
> + ret = cpu_set_valid(arg3, arg4);
> + if (ret != 0) {
> + return ret;
> + }
> + } else if (arg4 != 0) {
> + return -TARGET_EINVAL;
> + }
> +
> + /* no pairs */
> + if (arg2 == 0) {
> + return 0;
> + }
> +
> + host_pairs = lock_user(VERIFY_WRITE, arg1,
> + sizeof(*host_pairs) * (size_t)arg2, 0);
> + if (host_pairs == NULL) {
> + return -TARGET_EFAULT;
> + }
> + risc_hwprobe_fill_pairs(cpu_env, host_pairs, arg2);
> + unlock_user(host_pairs, arg1, sizeof(*host_pairs) * (size_t)arg2);
> + return 0;
> +}
> +#endif /* TARGET_NR_riscv_hwprobe */
> +
> #if defined(TARGET_NR_pivot_root) && defined(__NR_pivot_root)
> _syscall2(int, pivot_root, const char *, new_root, const char *, put_old)
> #endif
> @@ -13571,6 +13712,11 @@ static abi_long do_syscall1(CPUArchState *cpu_env,
> int num, abi_long arg1,
> return ret;
> #endif
>
> +#if defined(TARGET_NR_riscv_hwprobe)
> + case TARGET_NR_riscv_hwprobe:
> + return do_riscv_hwprobe(cpu_env, arg1, arg2, arg3, arg4, arg5);
> +#endif
> +
> default:
> qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
> return -TARGET_ENOSYS;
> --
> 2.39.2
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
riscv_hwprobe() hasn't been released yet, but it's in Linus' tree so
unless something unforseen happens it should show up in 6.4 in a few
weeks.