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

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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.
This commit is contained in:
Daniel Bertalan 2023-08-11 10:47:31 +02:00
parent 87f4b0f1c2
commit 286984750e
12 changed files with 22 additions and 37 deletions
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7
Kernel/Syscalls/write.cpp
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@ -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;