Add CapbilityPtr and Add SuccessAddr and SuccessPtr syscall variants
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| // Licensed under the Apache License, Version 2.0 or the MIT License. | ||
| // SPDX-License-Identifier: Apache-2.0 OR MIT | ||
| // Copyright Google LLC 2024. | ||
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| //! Defines the MetaPtr type | ||
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| use core::fmt::{Formatter, LowerHex, UpperHex}; | ||
| use core::ops::AddAssign; | ||
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| /// A pointer with target specific metadata. | ||
| /// This should be used any time the kernel wishes to grant authority to the user, or any time | ||
| /// the user should be required to prove validity of a pointer. | ||
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| #[derive(Default, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] | ||
| #[repr(transparent)] | ||
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| pub struct MetaPtr { | ||
| ptr: usize, | ||
| } | ||
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| #[derive(Copy, Clone, PartialEq)] | ||
| pub enum MetaPermissions { | ||
| Any, | ||
| Read, | ||
| Write, | ||
| ReadWrite, | ||
| Execute, | ||
| } | ||
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| impl From<MetaPtr> for usize { | ||
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There was a problem hiding this comment. I think this is OK because a
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There was a problem hiding this comment. I can add that too (it might even exist as a method?), but this one gets used a lot in syscall / return argument handling.
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There was a problem hiding this comment. Ah got it. Does this imply that those arguments or returns should actually be
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There was a problem hiding this comment. I think its happening a lot because values that are usize, or even eventually u32, are being passed in registers that can hold something as wide as @bradjc has suggested that maybe those should be a separate I suppose, fairly, one could imagine a platform with pointers that are smaller than u32, in which case really RegisterData would wrap around the largest type.
Contributor
There was a problem hiding this comment. Documenting that The fact that some CHERI systems use different registers for integers and capabilities however, does throw a wrench into the works. However, there are two obvious ways that come to mind for how we might choose to handle that at the ABI level:
In both cases, it makes sense to only use [1] libtock-rs just calls this
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There was a problem hiding this comment. I am not convinced
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| #[inline] | ||
| fn from(from: MetaPtr) -> Self { | ||
| from.ptr | ||
| } | ||
| } | ||
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| impl From<usize> for MetaPtr { | ||
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| #[inline] | ||
| fn from(from: usize) -> Self { | ||
| Self { ptr: from } | ||
| } | ||
| } | ||
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| impl UpperHex for MetaPtr { | ||
| #[inline] | ||
| fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result { | ||
| UpperHex::fmt(&self.ptr, f) | ||
| } | ||
| } | ||
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| impl LowerHex for MetaPtr { | ||
| #[inline] | ||
| fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result { | ||
| LowerHex::fmt(&self.ptr, f) | ||
| } | ||
| } | ||
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| impl AddAssign<usize> for MetaPtr { | ||
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| #[inline] | ||
| fn add_assign(&mut self, rhs: usize) { | ||
| self.ptr.add_assign(rhs) | ||
| } | ||
| } | ||
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| impl MetaPtr { | ||
| pub fn as_ptr(&self) -> *const () { | ||
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| self.ptr as *const () | ||
| } | ||
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| /// Convert to a raw pointer, checking that metadata allows a particular set of permissions over | ||
| /// a given number of bytes. | ||
| /// If the metadata does not allow for this, returns null. | ||
| /// If no such metadata exists, this succeeds. | ||
| #[inline] | ||
| pub fn as_ptr_checked(&self, _length: usize, _perms: MetaPermissions) -> *const () { | ||
| self.ptr as *const () | ||
| } | ||
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| #[inline] | ||
| pub fn new_with_metadata( | ||
| ptr: *const (), | ||
| _base: usize, | ||
| _length: usize, | ||
| _perms: MetaPermissions, | ||
| ) -> Self { | ||
| Self { ptr: ptr as usize } | ||
| } | ||
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| #[inline] | ||
| pub fn map_or<U, F>(&self, default: U, f: F) -> U | ||
| where | ||
| F: FnOnce(&Self) -> U, | ||
| { | ||
| if self.ptr == 0usize { | ||
| default | ||
| } else { | ||
| f(self) | ||
| } | ||
| } | ||
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| #[inline] | ||
| pub fn map_or_else<U, D, F>(&self, default: D, f: F) -> U | ||
| where | ||
| D: FnOnce() -> U, | ||
| F: FnOnce(&Self) -> U, | ||
| { | ||
| let addr: usize = (*self).into(); | ||
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| if addr == 0 { | ||
| default() | ||
| } else { | ||
| f(self) | ||
| } | ||
| } | ||
| } | ||
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