Merge "kernel_api: Implement riscv_hwprobe" into main

4 files changed, 97 insertions, 0 deletions

diff --git a/kernel_api/riscv64/gen_syscall_emulation_riscv64_to_x86_64-inl.h b/kernel_api/riscv64/gen_syscall_emulation_riscv64_to_x86_64-inl.h
index 5c9ba7b4..4e241a15 100644
--- a/kernel_api/riscv64/gen_syscall_emulation_riscv64_to_x86_64-inl.h
+++ b/kernel_api/riscv64/gen_syscall_emulation_riscv64_to_x86_64-inl.h
@@ -524,6 +524,9 @@ long RunGuestSyscallImpl(long guest_nr,
     case 259:  // __NR_riscv_flush_icache
       // missing on x86_64
       return RunGuestSyscall___NR_riscv_flush_icache(arg_1, arg_2, arg_3);
+    case 258:  // __NR_riscv_hwprobe
+      // missing on x86_64
+      return RunGuestSyscall___NR_riscv_hwprobe(arg_1, arg_2, arg_3, arg_4, arg_5);
     case 293:  // __NR_rseq
       // missing prototype
       KAPI_TRACE("unsupported syscall __NR_rseq");
diff --git a/kernel_api/riscv64/guest_types.h b/kernel_api/riscv64/guest_types.h
index 6fe7e810..55faefe1 100644
--- a/kernel_api/riscv64/guest_types.h
+++ b/kernel_api/riscv64/guest_types.h
@@ -107,6 +107,40 @@ CHECK_FIELD_LAYOUT(Guest_stat, st_atim, 576, 128);
 CHECK_FIELD_LAYOUT(Guest_stat, st_mtim, 704, 128);
 CHECK_FIELD_LAYOUT(Guest_stat, st_ctim, 832, 128);
 
+struct Guest_riscv_hwprobe {
+  int64_t key;
+  uint64_t value;
+};
+
+CHECK_STRUCT_LAYOUT(Guest_riscv_hwprobe, 128, 64);
+CHECK_FIELD_LAYOUT(Guest_riscv_hwprobe, key, 0, 64);
+CHECK_FIELD_LAYOUT(Guest_riscv_hwprobe, value, 64, 64);
+
+// Each RISCV_HWPROBE_KEY_* represents a capability key. These constants are sorted
+// such that each capability key appears in numeric order, followed by the possible
+// values for that key in numeric order.
+// clang-format off
+#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_IMA_V                   (1 << 2)
+#define RISCV_HWPROBE_EXT_ZBA                 (1 << 3)
+#define RISCV_HWPROBE_EXT_ZBB                 (1 << 4)
+#define RISCV_HWPROBE_EXT_ZBS                 (1 << 5)
+#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)
+// clang-format on
+
 }  // namespace berberis
 
 #endif  // BERBERIS_KERNEL_API_RISCV64_GUEST_TYPES_ARCH_H_
diff --git a/kernel_api/riscv64/syscall_emulation.cc b/kernel_api/riscv64/syscall_emulation.cc
index 0a56a728..f9ad1388 100644
--- a/kernel_api/riscv64/syscall_emulation.cc
+++ b/kernel_api/riscv64/syscall_emulation.cc
@@ -15,8 +15,10 @@
  */
 
 #include <fcntl.h>  // AT_FDCWD, AT_SYMLINK_NOFOLLOW
+#include <linux/sched.h>
 #include <linux/unistd.h>
 #include <sys/stat.h>
+#include <sys/sysinfo.h>
 #include <sys/types.h>
 
 #include <cerrno>
@@ -65,6 +67,35 @@ int FstatatForGuest(int dirfd, const char* path, struct stat* buf, int flags) {
   return syscall(__NR_newfstatat, dirfd, real_path ? real_path : path, buf, flags);
 }
 
+void Hwprobe(Guest_riscv_hwprobe& pair) {
+  switch (pair.key) {
+    case RISCV_HWPROBE_KEY_MVENDORID:
+      pair.value = 0;
+      break;
+    case RISCV_HWPROBE_KEY_MARCHID:
+      pair.value = 0;
+      break;
+    case RISCV_HWPROBE_KEY_MIMPID:
+      pair.value = 0;
+      break;
+    case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
+      pair.value = RISCV_HWPROBE_BASE_BEHAVIOR_IMA;
+      break;
+    case RISCV_HWPROBE_KEY_IMA_EXT_0:
+      pair.value = RISCV_HWPROBE_IMA_FD | RISCV_HWPROBE_IMA_C | RISCV_HWPROBE_IMA_V |
+                   RISCV_HWPROBE_EXT_ZBA | RISCV_HWPROBE_EXT_ZBB | RISCV_HWPROBE_EXT_ZBS;
+      break;
+    case RISCV_HWPROBE_KEY_CPUPERF_0:
+      pair.value = RISCV_HWPROBE_MISALIGNED_FAST;
+      break;
+    default:
+      TRACE("unsupported __riscv_hwprobe capability key: %ld", pair.key);
+      pair.key = -1;
+      pair.value = 0;
+      break;
+  }
+}
+
 long RunGuestSyscall___NR_execveat(long arg_1, long arg_2, long arg_3, long arg_4, long arg_5) {
   UNUSED(arg_1, arg_2, arg_3, arg_4, arg_5);
   KAPI_TRACE("unimplemented syscall __NR_execveat");
@@ -104,6 +135,29 @@ long RunGuestSyscall___NR_newfstatat(long arg_1, long arg_2, long arg_3, long ar
   return result;
 }
 
+long RunGuestSyscall___NR_riscv_hwprobe(long arg_1,
+                                        long arg_2,
+                                        long arg_3,
+                                        long arg_4,
+                                        long arg_5) {
+  UNUSED(arg_3, arg_4);  // cpu_count, cpus_in
+
+  // There are currently no flags defined by the kernel. This may change in the future.
+  static constexpr unsigned int kFlagsAll = 0;
+
+  auto pairs = bit_cast<Guest_riscv_hwprobe*>(arg_1);
+  auto pair_count = bit_cast<size_t>(arg_2);
+  auto flags = static_cast<unsigned int>(bit_cast<unsigned long>(arg_5));
+  if ((flags & ~kFlagsAll) != 0) {
+    return -EINVAL;
+  }
+
+  for (size_t i = 0; i < pair_count; ++i) {
+    Hwprobe(pairs[i]);
+  }
+  return 0;
+}
+
 long RunGuestSyscall___NR_riscv_flush_icache(long arg_1, long arg_2, long arg_3) {
   static constexpr uint64_t kFlagsLocal = 1UL;
   static constexpr uint64_t kFlagsAll = kFlagsLocal;
diff --git a/kernel_api/tools/custom_syscalls.json b/kernel_api/tools/custom_syscalls.json
index 356e80c4..b91ecce0 100644
--- a/kernel_api/tools/custom_syscalls.json
+++ b/kernel_api/tools/custom_syscalls.json
@@ -201,6 +201,12 @@
       "params": ["void*", "void*", "int32"]
     }
   },
+  "__NR_riscv_hwprobe": {
+    "riscv64": {
+      "id": "258",
+      "params": ["struct riscv_hwprobe*", "size_t", "size_t", "unsigned long*", "unsigned int"]
+    }
+  },
   "__NR_rt_sigaction": {
     "custom_reason": "changes signal action"
   },