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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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5
Kernel/Syscalls/read.cpp
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@ -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);