Kernel+LibC: Pass 64-bit integers in syscalls by value

Now that support for 32-bit x86 has been removed, we don't have to worry
about the top half of `off_t`/`u64` values being chopped off when we try
to pass them in registers. Therefore, we no longer need the workaround
of pointers to stack-allocated values to syscalls.

Note that this changes the system call ABI, so statically linked
programs will have to be re-linked.

Kernel/Syscalls/fallocate.cpp

@@ -13,16 +13,14 @@
 namespace Kernel {
 
 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html
-ErrorOr<FlatPtr> Process::sys$posix_fallocate(int fd, Userspace<off_t const*> userspace_offset, Userspace<off_t const*> userspace_length)
+ErrorOr<FlatPtr> Process::sys$posix_fallocate(int fd, off_t offset, off_t length)
 {
     VERIFY_NO_PROCESS_BIG_LOCK(this);
     TRY(require_promise(Pledge::stdio));
 
     // [EINVAL] The len argument is less than zero, or the offset argument is less than zero, or the underlying file system does not support this operation.
-    auto offset = TRY(copy_typed_from_user(userspace_offset));
     if (offset < 0)
         return EINVAL;
-    auto length = TRY(copy_typed_from_user(userspace_length));
     if (length <= 0)
         return EINVAL;
 

Kernel/Syscalls/ftruncate.cpp

@@ -9,13 +9,10 @@
 
 namespace Kernel {
 
-// NOTE: The length is passed by pointer because off_t is 64bit,
-// hence it can't be passed by register on 32bit platforms.
-ErrorOr<FlatPtr> Process::sys$ftruncate(int fd, Userspace<off_t const*> userspace_length)
+ErrorOr<FlatPtr> Process::sys$ftruncate(int fd, off_t length)
 {
     VERIFY_NO_PROCESS_BIG_LOCK(this);
     TRY(require_promise(Pledge::stdio));
-    auto length = TRY(copy_typed_from_user(userspace_length));
     if (length < 0)
         return EINVAL;
     auto description = TRY(open_file_description(fd));

Kernel/Syscalls/profiling.cpp

@@ -16,14 +16,11 @@ bool g_profiling_all_threads;
 PerformanceEventBuffer* g_global_perf_events;
 u64 g_profiling_event_mask;
 
-// NOTE: event_mask needs to be passed as a pointer as u64
-//       does not fit into a register on 32bit architectures.
-ErrorOr<FlatPtr> Process::sys$profiling_enable(pid_t pid, Userspace<u64 const*> userspace_event_mask)
+ErrorOr<FlatPtr> Process::sys$profiling_enable(pid_t pid, u64 event_mask)
 {
     VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
     TRY(require_no_promises());
 
-    auto const event_mask = TRY(copy_typed_from_user(userspace_event_mask));
     return profiling_enable(pid, event_mask);
 }
 

Kernel/Syscalls/read.cpp

@@ -101,9 +101,7 @@ ErrorOr<FlatPtr> Process::read_impl(int fd, Userspace<u8*> buffer, size_t size)
     return TRY(description->read(user_buffer, size));
 }
 
-// NOTE: The offset is passed by pointer because off_t is 64bit,
-// hence it can't be passed by register on 32bit platforms.
-ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size, Userspace<off_t const*> userspace_offset)
+ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size, off_t offset)
 {
     VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
     TRY(require_promise(Pledge::stdio));
@@ -111,7 +109,6 @@ ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size,
         return 0;
     if (size > NumericLimits<ssize_t>::max())
         return EINVAL;
-    auto offset = TRY(copy_typed_from_user(userspace_offset));
     if (offset < 0)
         return EINVAL;
     dbgln_if(IO_DEBUG, "sys$pread({}, {}, {}, {})", fd, buffer.ptr(), size, offset);

Kernel/Syscalls/write.cpp

@@ -11,9 +11,7 @@
 
 namespace Kernel {
 
-// NOTE: The offset is passed by pointer because off_t is 64bit,
-// hence it can't be passed by register on 32bit platforms.
-ErrorOr<FlatPtr> Process::sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, Userspace<off_t const*> userspace_offset)
+ErrorOr<FlatPtr> Process::sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, off_t base_offset)
 {
     VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
     TRY(require_promise(Pledge::stdio));
@@ -33,11 +31,10 @@ ErrorOr<FlatPtr> Process::sys$pwritev(int fd, Userspace<const struct iovec*> iov
             return EINVAL;
     }
 
-    // NOTE: Negative offset means "operate like writev" which seeks the file.
-    auto base_offset = TRY(copy_typed_from_user(userspace_offset));
     auto description = TRY(open_file_description(fd));
     if (!description->is_writable())
         return EBADF;
+    // NOTE: Negative offset means "operate like writev" which seeks the file.
     if (base_offset >= 0 && !description->file().is_seekable())
         return EINVAL;
 

Kernel/Tasks/Process.h

@@ -337,17 +337,17 @@ public:
     ErrorOr<FlatPtr> sys$open(Userspace<Syscall::SC_open_params const*>);
     ErrorOr<FlatPtr> sys$close(int fd);
     ErrorOr<FlatPtr> sys$read(int fd, Userspace<u8*>, size_t);
-    ErrorOr<FlatPtr> sys$pread(int fd, Userspace<u8*>, size_t, Userspace<off_t const*>);
+    ErrorOr<FlatPtr> sys$pread(int fd, Userspace<u8*>, size_t, off_t);
     ErrorOr<FlatPtr> sys$readv(int fd, Userspace<const struct iovec*> iov, int iov_count);
     ErrorOr<FlatPtr> sys$write(int fd, Userspace<u8 const*>, size_t);
-    ErrorOr<FlatPtr> sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, Userspace<off_t const*>);
+    ErrorOr<FlatPtr> sys$pwritev(int fd, Userspace<const struct iovec*> iov, int iov_count, off_t);
     ErrorOr<FlatPtr> sys$fstat(int fd, Userspace<stat*>);
     ErrorOr<FlatPtr> sys$stat(Userspace<Syscall::SC_stat_params const*>);
     ErrorOr<FlatPtr> sys$annotate_mapping(Userspace<void*>, int flags);
     ErrorOr<FlatPtr> sys$lseek(int fd, Userspace<off_t*>, int whence);
-    ErrorOr<FlatPtr> sys$ftruncate(int fd, Userspace<off_t const*>);
+    ErrorOr<FlatPtr> sys$ftruncate(int fd, off_t);
     ErrorOr<FlatPtr> sys$futimens(Userspace<Syscall::SC_futimens_params const*>);
-    ErrorOr<FlatPtr> sys$posix_fallocate(int fd, Userspace<off_t const*>, Userspace<off_t const*>);
+    ErrorOr<FlatPtr> sys$posix_fallocate(int fd, off_t, off_t);
     ErrorOr<FlatPtr> sys$kill(pid_t pid_or_pgid, int sig);
     [[noreturn]] void sys$exit(int status);
     ErrorOr<FlatPtr> sys$sigreturn(RegisterState& registers);
@@ -443,7 +443,7 @@ public:
     ErrorOr<FlatPtr> sys$getrandom(Userspace<void*>, size_t, unsigned int);
     ErrorOr<FlatPtr> sys$getkeymap(Userspace<Syscall::SC_getkeymap_params const*>);
     ErrorOr<FlatPtr> sys$setkeymap(Userspace<Syscall::SC_setkeymap_params const*>);
-    ErrorOr<FlatPtr> sys$profiling_enable(pid_t, Userspace<u64 const*>);
+    ErrorOr<FlatPtr> sys$profiling_enable(pid_t, u64);
     ErrorOr<FlatPtr> profiling_enable(pid_t, u64 event_mask);
     ErrorOr<FlatPtr> sys$profiling_disable(pid_t);
     ErrorOr<FlatPtr> sys$profiling_free_buffer(pid_t);

Userland/DevTools/UserspaceEmulator/Emulator.h

@@ -213,7 +213,7 @@ private:
     u32 virt$pledge(u32);
     int virt$poll(FlatPtr);
     int virt$profiling_disable(pid_t);
-    int virt$profiling_enable(pid_t);
+    int virt$profiling_enable(pid_t, u64);
     int virt$purge(int mode);
     u32 virt$read(int, FlatPtr, ssize_t);
     int virt$readlink(FlatPtr);

Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp

@@ -185,7 +185,7 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
     case SC_profiling_disable:
         return virt$profiling_disable(arg1);
     case SC_profiling_enable:
-        return virt$profiling_enable(arg1);
+        return virt$profiling_enable(arg1, arg2);
     case SC_purge:
         return virt$purge(arg1);
     case SC_read:
@@ -281,9 +281,9 @@ int Emulator::virt$recvfd(int socket, int options)
     return syscall(SC_recvfd, socket, options);
 }
 
-int Emulator::virt$profiling_enable(pid_t pid)
+int Emulator::virt$profiling_enable(pid_t pid, u64 mask)
 {
-    return syscall(SC_profiling_enable, pid);
+    return syscall(SC_profiling_enable, pid, mask);
 }
 
 int Emulator::virt$profiling_disable(pid_t pid)
@@ -474,11 +474,10 @@ int Emulator::virt$get_stack_bounds(FlatPtr base, FlatPtr size)
     return 0;
 }
 
-int Emulator::virt$ftruncate(int fd, FlatPtr length_addr)
+int Emulator::virt$ftruncate(int fd, off_t length)
 {
     off_t length;
-    mmu().copy_from_vm(&length, length_addr, sizeof(off_t));
-    return syscall(SC_ftruncate, fd, &length);
+    return syscall(SC_ftruncate, fd, length);
 }
 
 int Emulator::virt$uname(FlatPtr params_addr)

Userland/Libraries/LibC/fcntl.cpp

@@ -118,7 +118,7 @@ int posix_fadvise(int fd, off_t offset, off_t len, int advice)
 int posix_fallocate(int fd, off_t offset, off_t len)
 {
     // posix_fallocate does not set errno.
-    return -static_cast<int>(syscall(SC_posix_fallocate, fd, &offset, &len));
+    return -static_cast<int>(syscall(SC_posix_fallocate, fd, offset, len));
 }
 
 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/utimensat.html

Userland/Libraries/LibC/serenity.cpp

@@ -22,7 +22,7 @@ int disown(pid_t pid)
 
 int profiling_enable(pid_t pid, uint64_t event_mask)
 {
-    int rc = syscall(SC_profiling_enable, pid, &event_mask);
+    int rc = syscall(SC_profiling_enable, pid, event_mask);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 

Userland/Libraries/LibC/sys/uio.cpp

@@ -28,7 +28,7 @@ ssize_t pwritev(int fd, struct iovec const* iov, int iov_count, off_t offset)
 {
     __pthread_maybe_cancel();
 
-    int rc = syscall(SC_pwritev, fd, iov, iov_count, &offset);
+    int rc = syscall(SC_pwritev, fd, iov, iov_count, offset);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 }

Userland/Libraries/LibC/unistd.cpp

@@ -392,7 +392,7 @@ ssize_t pread(int fd, void* buf, size_t count, off_t offset)
 {
     __pthread_maybe_cancel();
 
-    int rc = syscall(SC_pread, fd, buf, count, &offset);
+    int rc = syscall(SC_pread, fd, buf, count, offset);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
@@ -897,7 +897,7 @@ char* getlogin()
 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html
 int ftruncate(int fd, off_t length)
 {
-    int rc = syscall(SC_ftruncate, fd, &length);
+    int rc = syscall(SC_ftruncate, fd, length);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }