From: Björn Roy Baron <[email protected]>
While there are default impls for these methods, using the respective C
api's is faster. Currently neither the existing nor these new
GlobalAlloc method implementations are actually called. Instead the
__rust_* function defined below the GlobalAlloc impl are used. With
rustc 1.71 these functions will be gone and all allocation calls will go
through the GlobalAlloc implementation.
Link: https://github.com/Rust-for-Linux/linux/issues/68
Signed-off-by: Björn Roy Baron <[email protected]>
---
rust/kernel/allocator.rs | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index 397a3dd57a9b..e0a27b1326b5 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/allocator.rs
@@ -21,6 +21,26 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
bindings::kfree(ptr as *const core::ffi::c_void);
}
}
+
+ unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
+ unsafe {
+ bindings::krealloc(
+ ptr as *const core::ffi::c_void,
+ new_size,
+ bindings::GFP_KERNEL,
+ ) as *mut u8
+ }
+ }
+
+ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+ unsafe {
+ bindings::krealloc(
+ core::ptr::null(),
+ layout.size(),
+ bindings::GFP_KERNEL | bindings::__GFP_ZERO,
+ ) as *mut u8
+ }
+ }
}
#[global_allocator]
---
base-commit: d2e3115d717197cb2bc020dd1f06b06538474ac3
change-id: 20230622-global_alloc_methods-abf5b5e38dba
Best regards,
--
Björn Roy Baron <[email protected]>
On 6/22/23 16:24, Björn Roy Baron via B4 Relay wrote:
> From: Björn Roy Baron <[email protected]>
>
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
> Signed-off-by: Björn Roy Baron <[email protected]>
> ---
> [...]
Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
On Thu, Jun 22, 2023 at 09:24:40PM +0200, Bj?rn Roy Baron via B4 Relay wrote:
> From: Bj?rn Roy Baron <[email protected]>
>
> While there are default impls for these methods, using the respective C
> api's is faster. Currently neither the existing nor these new
> GlobalAlloc method implementations are actually called. Instead the
> __rust_* function defined below the GlobalAlloc impl are used. With
> rustc 1.71 these functions will be gone and all allocation calls will go
> through the GlobalAlloc implementation.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/68
Nice! Although I think we need to do the simialr size adjustment as:
https://lore.kernel.org/rust-for-linux/[email protected]/
so I applied your patch onto my patch and came up with the following:
--------------------------------->8
diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index ce7a06bf7589..af723c2924dc 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/allocator.rs
@@ -9,8 +9,17 @@
struct KernelAllocator;
-unsafe impl GlobalAlloc for KernelAllocator {
- unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+impl KernelAllocator {
+ /// # Safety
+ ///
+ /// * `ptr` can be either null or a pointer which has been allocated by this allocator.
+ /// * `layout` must have a non-zero size.
+ unsafe fn krealloc_with_flags(
+ &self,
+ ptr: *mut u8,
+ layout: Layout,
+ flags: bindings::gfp_t,
+ ) -> *mut u8 {
// Customized layouts from `Layout::from_size_align()` can have size < align, so pads first.
let layout = layout.pad_to_align();
@@ -26,9 +35,22 @@ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
size = size.next_power_of_two();
}
- // `krealloc()` is used instead of `kmalloc()` because the latter is
- // an inline function and cannot be bound to as a result.
- unsafe { bindings::krealloc(ptr::null(), size, bindings::GFP_KERNEL) as *mut u8 }
+ // SAFETY:
+ //
+ // * `ptr` is either null or a pointer returned from a previous k{re}alloc() by the function
+ // safety requirement.
+ //
+ // * `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
+ // according to the function safety requirement) or a result from `next_power_of_two()`.
+ unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
+ }
+}
+
+unsafe impl GlobalAlloc for KernelAllocator {
+ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+ // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
+ // requirement.
+ unsafe { self.krealloc_with_flags(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
}
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
@@ -37,23 +59,30 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
}
}
- unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
- unsafe {
- bindings::krealloc(
- ptr as *const core::ffi::c_void,
- new_size,
- bindings::GFP_KERNEL,
- ) as *mut u8
- }
+ unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+ // SAFETY:
+ // * `new_size` when rounded up to the nearest multiple of `layout.align()`, will not
+ // overflow `isize` by the function safety requirement.
+ // * `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
+ let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
+
+ // SAFETY:
+ // * `ptr` is either null or a pointer allocated by this allocator by function safety
+ // requirement.
+ // * the size of `layout` is not zero because `new_size` is not zero by function safety
+ // requirement.
+ unsafe { self.krealloc_with_flags(ptr, layout, bindings::GFP_KERNEL) }
}
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+ // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
+ // requirement.
unsafe {
- bindings::krealloc(
- core::ptr::null(),
- layout.size(),
+ self.krealloc_with_flags(
+ ptr::null_mut(),
+ layout,
bindings::GFP_KERNEL | bindings::__GFP_ZERO,
- ) as *mut u8
+ )
}
}
}
Regards,
Boqun
> Signed-off-by: Bj?rn Roy Baron <[email protected]>
> ---
> rust/kernel/allocator.rs | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
> index 397a3dd57a9b..e0a27b1326b5 100644
> --- a/rust/kernel/allocator.rs
> +++ b/rust/kernel/allocator.rs
> @@ -21,6 +21,26 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> bindings::kfree(ptr as *const core::ffi::c_void);
> }
> }
> +
> + unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
> + unsafe {
> + bindings::krealloc(
> + ptr as *const core::ffi::c_void,
> + new_size,
> + bindings::GFP_KERNEL,
> + ) as *mut u8
> + }
> + }
> +
> + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
> + unsafe {
> + bindings::krealloc(
> + core::ptr::null(),
> + layout.size(),
> + bindings::GFP_KERNEL | bindings::__GFP_ZERO,
> + ) as *mut u8
> + }
> + }
> }
>
> #[global_allocator]
>
> ---
> base-commit: d2e3115d717197cb2bc020dd1f06b06538474ac3
> change-id: 20230622-global_alloc_methods-abf5b5e38dba
>
> Best regards,
> --
> Bj?rn Roy Baron <[email protected]>
>
On Friday, June 23rd, 2023 at 19:35, Boqun Feng <[email protected]> wrote:
> On Thu, Jun 22, 2023 at 09:24:40PM +0200, Björn Roy Baron via B4 Relay wrote:
>
> > From: Björn Roy Baron [email protected]
> >
> > While there are default impls for these methods, using the respective C
> > api's is faster. Currently neither the existing nor these new
> > GlobalAlloc method implementations are actually called. Instead the
> > _rust* function defined below the GlobalAlloc impl are used. With
> > rustc 1.71 these functions will be gone and all allocation calls will go
> > through the GlobalAlloc implementation.
> >
> > Link: https://github.com/Rust-for-Linux/linux/issues/68
>
>
> Nice! Although I think we need to do the simialr size adjustment as:
>
> https://lore.kernel.org/rust-for-linux/[email protected]/
>
> so I applied your patch onto my patch and came up with the following:
Right. That patch LGTM.
Cheers,
Björn
On Fri, 23 Jun 2023 10:35:00 -0700
Boqun Feng <[email protected]> wrote:
> On Thu, Jun 22, 2023 at 09:24:40PM +0200, Björn Roy Baron via B4 Relay wrote:
> > From: Björn Roy Baron <[email protected]>
> >
> > While there are default impls for these methods, using the respective C
> > api's is faster. Currently neither the existing nor these new
> > GlobalAlloc method implementations are actually called. Instead the
> > __rust_* function defined below the GlobalAlloc impl are used. With
> > rustc 1.71 these functions will be gone and all allocation calls will go
> > through the GlobalAlloc implementation.
> >
> > Link: https://github.com/Rust-for-Linux/linux/issues/68
>
> Nice! Although I think we need to do the simialr size adjustment as:
>
> https://lore.kernel.org/rust-for-linux/[email protected]/
>
> so I applied your patch onto my patch and came up with the following:
The diff LGTM.
>
> --------------------------------->8
> diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
> index ce7a06bf7589..af723c2924dc 100644
> --- a/rust/kernel/allocator.rs
> +++ b/rust/kernel/allocator.rs
> @@ -9,8 +9,17 @@
>
> struct KernelAllocator;
>
> -unsafe impl GlobalAlloc for KernelAllocator {
> - unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> +impl KernelAllocator {
> + /// # Safety
> + ///
> + /// * `ptr` can be either null or a pointer which has been allocated by this allocator.
> + /// * `layout` must have a non-zero size.
> + unsafe fn krealloc_with_flags(
> + &self,
> + ptr: *mut u8,
> + layout: Layout,
> + flags: bindings::gfp_t,
> + ) -> *mut u8 {
> // Customized layouts from `Layout::from_size_align()` can have size < align, so pads first.
> let layout = layout.pad_to_align();
>
> @@ -26,9 +35,22 @@ unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> size = size.next_power_of_two();
> }
>
> - // `krealloc()` is used instead of `kmalloc()` because the latter is
> - // an inline function and cannot be bound to as a result.
> - unsafe { bindings::krealloc(ptr::null(), size, bindings::GFP_KERNEL) as *mut u8 }
> + // SAFETY:
> + //
> + // * `ptr` is either null or a pointer returned from a previous k{re}alloc() by the function
> + // safety requirement.
> + //
> + // * `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
> + // according to the function safety requirement) or a result from `next_power_of_two()`.
> + unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
> + }
> +}
> +
> +unsafe impl GlobalAlloc for KernelAllocator {
> + unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
> }
>
> unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> @@ -37,23 +59,30 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> }
> }
>
> - unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
> - unsafe {
> - bindings::krealloc(
> - ptr as *const core::ffi::c_void,
> - new_size,
> - bindings::GFP_KERNEL,
> - ) as *mut u8
> - }
> + unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
> + // SAFETY:
> + // * `new_size` when rounded up to the nearest multiple of `layout.align()`, will not
> + // overflow `isize` by the function safety requirement.
> + // * `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
> + let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
> +
> + // SAFETY:
> + // * `ptr` is either null or a pointer allocated by this allocator by function safety
> + // requirement.
> + // * the size of `layout` is not zero because `new_size` is not zero by function safety
> + // requirement.
> + unsafe { self.krealloc_with_flags(ptr, layout, bindings::GFP_KERNEL) }
> }
>
> unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
> + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
> + // requirement.
> unsafe {
> - bindings::krealloc(
> - core::ptr::null(),
> - layout.size(),
> + self.krealloc_with_flags(
> + ptr::null_mut(),
> + layout,
> bindings::GFP_KERNEL | bindings::__GFP_ZERO,
> - ) as *mut u8
> + )
> }
> }
> }
>
>
> Regards,
> Boqun
>
> > Signed-off-by: Björn Roy Baron <[email protected]>
> > ---
> > rust/kernel/allocator.rs | 20 ++++++++++++++++++++
> > 1 file changed, 20 insertions(+)
> >
> > diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
> > index 397a3dd57a9b..e0a27b1326b5 100644
> > --- a/rust/kernel/allocator.rs
> > +++ b/rust/kernel/allocator.rs
> > @@ -21,6 +21,26 @@ unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
> > bindings::kfree(ptr as *const core::ffi::c_void);
> > }
> > }
> > +
> > + unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
> > + unsafe {
> > + bindings::krealloc(
> > + ptr as *const core::ffi::c_void,
> > + new_size,
> > + bindings::GFP_KERNEL,
> > + ) as *mut u8
> > + }
> > + }
> > +
> > + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
> > + unsafe {
> > + bindings::krealloc(
> > + core::ptr::null(),
> > + layout.size(),
> > + bindings::GFP_KERNEL | bindings::__GFP_ZERO,
> > + ) as *mut u8
> > + }
> > + }
> > }
> >
> > #[global_allocator]
> >
> > ---
> > base-commit: d2e3115d717197cb2bc020dd1f06b06538474ac3
> > change-id: 20230622-global_alloc_methods-abf5b5e38dba
> >
> > Best regards,
> > --
> > Björn Roy Baron <[email protected]>
> >
On Sat, Jun 24, 2023 at 02:40:23PM +0000, Bj?rn Roy Baron wrote:
> On Friday, June 23rd, 2023 at 19:35, Boqun Feng <[email protected]> wrote:
>
> > On Thu, Jun 22, 2023 at 09:24:40PM +0200, Bj?rn Roy Baron via B4 Relay wrote:
> >
> > > From: Bj?rn Roy Baron [email protected]
> > >
> > > While there are default impls for these methods, using the respective C
> > > api's is faster. Currently neither the existing nor these new
> > > GlobalAlloc method implementations are actually called. Instead the
> > > _rust* function defined below the GlobalAlloc impl are used. With
> > > rustc 1.71 these functions will be gone and all allocation calls will go
> > > through the GlobalAlloc implementation.
> > >
> > > Link: https://github.com/Rust-for-Linux/linux/issues/68
> >
> >
> > Nice! Although I think we need to do the simialr size adjustment as:
> >
> > https://lore.kernel.org/rust-for-linux/[email protected]/
> >
> > so I applied your patch onto my patch and came up with the following:
>
> Right. That patch LGTM.
>
Thank you and Gary for the diff review, I will fold it into your
original patch and resend.
Regards,
Boqun
> Cheers,
> Bj?rn