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* [RFC] linux-user/riscv: Add syscall riscv_hwprobe
@ 2023-06-01 12:27 Robbin Ehn
  2023-06-01 15:15 ` Richard Henderson
  0 siblings, 1 reply; 3+ messages in thread
From: Robbin Ehn @ 2023-06-01 12:27 UTC (permalink / raw)
  To: qemu-devel; +Cc: laurent

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>
---
 linux-headers/asm-riscv/unistd.h |   9 +++
 linux-user/riscv/cpu_loop.c      | 119 ++++++++++++++++++++++++++++++-
 linux-user/riscv/syscall32_nr.h  |   1 +
 linux-user/riscv/syscall64_nr.h  |   1 +
 4 files changed, 129 insertions(+), 1 deletion(-)

diff --git a/linux-headers/asm-riscv/unistd.h b/linux-headers/asm-riscv/unistd.h
index 73d7cdd2ec..950ab3fd44 100644
--- a/linux-headers/asm-riscv/unistd.h
+++ b/linux-headers/asm-riscv/unistd.h
@@ -43,3 +43,12 @@
 #define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)
 #endif
 __SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)
+
+/*
+ * Allows userspace to query the kernel for CPU architecture and
+ * microarchitecture details across a given set of CPUs.
+ */
+#ifndef __NR_riscv_hwprobe
+#define __NR_riscv_hwprobe (__NR_arch_specific_syscall + 14)
+#endif
+__SYSCALL(__NR_riscv_hwprobe, sys_riscv_hwprobe)
diff --git a/linux-user/riscv/cpu_loop.c b/linux-user/riscv/cpu_loop.c
index bffca7db12..5207739185 100644
--- a/linux-user/riscv/cpu_loop.c
+++ b/linux-user/riscv/cpu_loop.c
@@ -26,6 +26,117 @@
 #include "elf.h"
 #include "semihosting/common-semi.h"
 
+#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 {
+    int64_t  key;
+    uint64_t value;
+};
+
+static void hwprobe_one_pair(CPURISCVState *env, struct riscv_hwprobe *pair)
+{
+    const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
+
+    pair->value = 0;
+
+    switch (pair->key) {
+    case RISCV_HWPROBE_KEY_MVENDORID:
+        pair->value = cfg->mvendorid;
+        break;
+    case RISCV_HWPROBE_KEY_MARCHID:
+        pair->value = cfg->marchid;
+        break;
+    case RISCV_HWPROBE_KEY_MIMPID:
+        pair->value = cfg->mimpid;
+        break;
+    case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
+        pair->value = riscv_has_ext(env, RVI) &&
+                      riscv_has_ext(env, RVM) &&
+                      riscv_has_ext(env, RVA) ?
+                      RISCV_HWPROBE_BASE_BEHAVIOR_IMA : 0;
+        break;
+    case RISCV_HWPROBE_KEY_IMA_EXT_0:
+        pair->value = riscv_has_ext(env, RVF) &&
+                      riscv_has_ext(env, RVD) ?
+                      RISCV_HWPROBE_IMA_FD : 0;
+        pair->value |= riscv_has_ext(env, RVC) ?
+                       RISCV_HWPROBE_IMA_C : pair->value;
+        break;
+    case RISCV_HWPROBE_KEY_CPUPERF_0:
+        pair->value = RISCV_HWPROBE_MISALIGNED_UNKNOWN;
+        break;
+    default:
+        pair->key = -1;
+    break;
+    }
+}
+
+static long sys_riscv_hwprobe(CPURISCVState *env,
+                              abi_ulong user_pairs,
+                              size_t pair_count,
+                              size_t cpu_count,
+                              abi_ulong user_cpus,
+                              unsigned int flags)
+{
+    struct riscv_hwprobe *host_pairs;
+    cpu_set_t *host_cpus = NULL;
+    size_t cpu_setsize = 0;
+
+    /* flags must be 0 */
+    if (flags != 0) {
+        return 1
+    };
+
+    /* inconsistence cpu_set */
+    if (cpu_count != 0 && user_cpus == 0) {
+        return 1;
+    }
+
+    host_pairs = lock_user(VERIFY_WRITE, user_pairs,
+                           sizeof(*host_pairs) * pair_count, 0);
+
+    if (host_pairs == NULL) {
+        return 1;
+    }
+
+    if (user_cpus != 0) {
+        cpu_setsize = CPU_ALLOC_SIZE(user_cpus);
+        host_cpus = lock_user(VERIFY_READ, user_cpus, cpu_setsize, 0);
+    }
+
+    /* cpuset is ignored, symmetric CPUs in qemu */
+
+    for (struct riscv_hwprobe *ipairs = host_pairs;
+         pair_count > 0;
+         pair_count--, ipairs++) {
+        hwprobe_one_pair(env, ipairs);
+    }
+
+    if (host_cpus != 0) {
+        unlock_user(host_cpus, user_cpus, cpu_setsize);
+    }
+
+    unlock_user(host_pairs, user_pairs, sizeof(*host_pairs) * pair_count);
+    return 0;
+};
+
 void cpu_loop(CPURISCVState *env)
 {
     CPUState *cs = env_cpu(env);
@@ -47,7 +158,13 @@ void cpu_loop(CPURISCVState *env)
             break;
         case RISCV_EXCP_U_ECALL:
             env->pc += 4;
-            if (env->gpr[xA7] == TARGET_NR_arch_specific_syscall + 15) {
+            if (env->gpr[xA7] == TARGET_NR_arch_specific_syscall + 14) {
+                /* riscv_hwprobe */
+                ret = sys_riscv_hwprobe(env,
+                                        env->gpr[xA0], env->gpr[xA1],
+                                        env->gpr[xA2], env->gpr[xA3],
+                                        env->gpr[xA4]);
+            } else if (env->gpr[xA7] == TARGET_NR_arch_specific_syscall + 15) {
                 /* riscv_flush_icache_syscall is a no-op in QEMU as
                    self-modifying code is automatically detected */
                 ret = 0;
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
-- 
2.39.2



^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-06-02  6:26 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2023-06-01 12:27 [RFC] linux-user/riscv: Add syscall riscv_hwprobe Robbin Ehn
2023-06-01 15:15 ` Richard Henderson
2023-06-02  6:25   ` Robbin Ehn

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