Rust fixes for v6.15

Toolchain and infrastructure:
 
  - Fix missing KASAN LLVM flags on first build (and fix spurious
    rebuilds) by skipping '--target'.
 
  - Fix Make < 4.3 build error by using '$(pound)'.
 
  - Fix UML build error by removing 'volatile' qualifier from io helpers.
 
  - Fix UML build error by adding 'dma_{alloc,free}_attrs()'  helpers.
 
  - Clean gendwarfksyms warnings by avoiding to export '__pfx' symbols.
 
  - Clean objtool warning by adding a new 'noreturn' function for 1.86.0.
 
  - Disable 'needless_continue' Clippy lint due to new 1.86.0 warnings.
 
  - Add missing 'ffi' crate to 'generate_rust_analyzer.py'.
 
 'pin-init' crate:
 
  - Import a couple fixes from upstream.
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Merge tag 'rust-fixes-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull rust fixes from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Fix missing KASAN LLVM flags on first build (and fix spurious
     rebuilds) by skipping '--target'

   - Fix Make < 4.3 build error by using '$(pound)'

   - Fix UML build error by removing 'volatile' qualifier from io
     helpers

   - Fix UML build error by adding 'dma_{alloc,free}_attrs()' helpers

   - Clean gendwarfksyms warnings by avoiding to export '__pfx' symbols

   - Clean objtool warning by adding a new 'noreturn' function for
     1.86.0

   - Disable 'needless_continue' Clippy lint due to new 1.86.0 warnings

   - Add missing 'ffi' crate to 'generate_rust_analyzer.py'

  'pin-init' crate:

   - Import a couple fixes from upstream"

* tag 'rust-fixes-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
  rust: helpers: Add dma_alloc_attrs() and dma_free_attrs()
  rust: helpers: Remove volatile qualifier from io helpers
  rust: kbuild: use `pound` to support GNU Make < 4.3
  objtool/rust: add one more `noreturn` Rust function for Rust 1.86.0
  rust: kasan/kbuild: fix missing flags on first build
  rust: disable `clippy::needless_continue`
  rust: kbuild: Don't export __pfx symbols
  rust: pin-init: use Markdown autolinks in Rust comments
  rust: pin-init: alloc: restrict `impl ZeroableOption` for `Box` to `T: Sized`
  scripts: generate_rust_analyzer: Add ffi crate

MAINTAINERS

@@ -7021,6 +7021,7 @@ L:	rust-for-linux@vger.kernel.org
 S:	Supported
 W:	https://rust-for-linux.com
 T:	git https://github.com/Rust-for-Linux/linux.git alloc-next
+F:	rust/helpers/dma.c
 F:	rust/kernel/dma.rs
 F:	samples/rust/rust_dma.rs
 

Makefile

@@ -477,7 +477,6 @@ export rust_common_flags := --edition=2021 \
 			    -Wclippy::ignored_unit_patterns \
 			    -Wclippy::mut_mut \
 			    -Wclippy::needless_bitwise_bool \
-			    -Wclippy::needless_continue \
 			    -Aclippy::needless_lifetimes \
 			    -Wclippy::no_mangle_with_rust_abi \
 			    -Wclippy::undocumented_unsafe_blocks \

rust/Makefile

@@ -368,7 +368,7 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ;
 $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
 	$(call if_changed_dep,bindgen)
 
-rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ && $$3!~/__odr_asan/ { printf $(2),$$3 }'
+rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__(pfx|cfi|odr_asan)/ { printf $(2),$$3 }'
 
 quiet_cmd_exports = EXPORTS $@
       cmd_exports = \

rust/helpers/dma.c

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/dma-mapping.h>
+
+void *rust_helper_dma_alloc_attrs(struct device *dev, size_t size,
+				  dma_addr_t *dma_handle, gfp_t flag,
+				  unsigned long attrs)
+{
+	return dma_alloc_attrs(dev, size, dma_handle, flag, attrs);
+}
+
+void rust_helper_dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
+				dma_addr_t dma_handle, unsigned long attrs)
+{
+	dma_free_attrs(dev, size, cpu_addr, dma_handle, attrs);
+}

rust/helpers/helpers.c

@@ -14,6 +14,7 @@
 #include "cpumask.c"
 #include "cred.c"
 #include "device.c"
+#include "dma.c"
 #include "err.c"
 #include "fs.c"
 #include "io.c"

rust/helpers/io.c

@@ -7,94 +7,94 @@ void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size)
 	return ioremap(offset, size);
 }
 
-void rust_helper_iounmap(volatile void __iomem *addr)
+void rust_helper_iounmap(void __iomem *addr)
 {
 	iounmap(addr);
 }
 
-u8 rust_helper_readb(const volatile void __iomem *addr)
+u8 rust_helper_readb(const void __iomem *addr)
 {
 	return readb(addr);
 }
 
-u16 rust_helper_readw(const volatile void __iomem *addr)
+u16 rust_helper_readw(const void __iomem *addr)
 {
 	return readw(addr);
 }
 
-u32 rust_helper_readl(const volatile void __iomem *addr)
+u32 rust_helper_readl(const void __iomem *addr)
 {
 	return readl(addr);
 }
 
 #ifdef CONFIG_64BIT
-u64 rust_helper_readq(const volatile void __iomem *addr)
+u64 rust_helper_readq(const void __iomem *addr)
 {
 	return readq(addr);
 }
 #endif
 
-void rust_helper_writeb(u8 value, volatile void __iomem *addr)
+void rust_helper_writeb(u8 value, void __iomem *addr)
 {
 	writeb(value, addr);
 }
 
-void rust_helper_writew(u16 value, volatile void __iomem *addr)
+void rust_helper_writew(u16 value, void __iomem *addr)
 {
 	writew(value, addr);
 }
 
-void rust_helper_writel(u32 value, volatile void __iomem *addr)
+void rust_helper_writel(u32 value, void __iomem *addr)
 {
 	writel(value, addr);
 }
 
 #ifdef CONFIG_64BIT
-void rust_helper_writeq(u64 value, volatile void __iomem *addr)
+void rust_helper_writeq(u64 value, void __iomem *addr)
 {
 	writeq(value, addr);
 }
 #endif
 
-u8 rust_helper_readb_relaxed(const volatile void __iomem *addr)
+u8 rust_helper_readb_relaxed(const void __iomem *addr)
 {
 	return readb_relaxed(addr);
 }
 
-u16 rust_helper_readw_relaxed(const volatile void __iomem *addr)
+u16 rust_helper_readw_relaxed(const void __iomem *addr)
 {
 	return readw_relaxed(addr);
 }
 
-u32 rust_helper_readl_relaxed(const volatile void __iomem *addr)
+u32 rust_helper_readl_relaxed(const void __iomem *addr)
 {
 	return readl_relaxed(addr);
 }
 
 #ifdef CONFIG_64BIT
-u64 rust_helper_readq_relaxed(const volatile void __iomem *addr)
+u64 rust_helper_readq_relaxed(const void __iomem *addr)
 {
 	return readq_relaxed(addr);
 }
 #endif
 
-void rust_helper_writeb_relaxed(u8 value, volatile void __iomem *addr)
+void rust_helper_writeb_relaxed(u8 value, void __iomem *addr)
 {
 	writeb_relaxed(value, addr);
 }
 
-void rust_helper_writew_relaxed(u16 value, volatile void __iomem *addr)
+void rust_helper_writew_relaxed(u16 value, void __iomem *addr)
 {
 	writew_relaxed(value, addr);
 }
 
-void rust_helper_writel_relaxed(u32 value, volatile void __iomem *addr)
+void rust_helper_writel_relaxed(u32 value, void __iomem *addr)
 {
 	writel_relaxed(value, addr);
 }
 
 #ifdef CONFIG_64BIT
-void rust_helper_writeq_relaxed(u64 value, volatile void __iomem *addr)
+void rust_helper_writeq_relaxed(u64 value, void __iomem *addr)
 {
 	writeq_relaxed(value, addr);
 }

rust/pin-init/examples/pthread_mutex.rs

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
-// inspired by https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs
+// inspired by <https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs>
 #![allow(clippy::undocumented_unsafe_blocks)]
 #![cfg_attr(feature = "alloc", feature(allocator_api))]
 #[cfg(not(windows))]

rust/pin-init/src/alloc.rs

@@ -17,11 +17,9 @@ use crate::{
 
 pub extern crate alloc;
 
-// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
-//
-// In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant and there
-// is no problem with a VTABLE pointer being null.
-unsafe impl<T: ?Sized> ZeroableOption for Box<T> {}
+// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
+unsafe impl<T> ZeroableOption for Box<T> {}
 
 /// Smart pointer that can initialize memory in-place.
 pub trait InPlaceInit<T>: Sized {

rust/pin-init/src/lib.rs

@@ -1447,7 +1447,7 @@ impl_zeroable! {
     {<T: ?Sized + Zeroable>} UnsafeCell<T>,
 
     // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
-    // https://doc.rust-lang.org/stable/std/option/index.html#representation).
+    // <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
     Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
     Option<NonZeroU128>, Option<NonZeroUsize>,
     Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,

scripts/Makefile.compiler

@@ -79,8 +79,8 @@ ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
 # Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage)
 # TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4
 __rustc-option = $(call try-run,\
-	echo '#![allow(missing_docs)]#![feature(no_core)]#![no_core]' | RUSTC_BOOTSTRAP=1\
-	$(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null,$(2)) $(3)\
+	echo '$(pound)![allow(missing_docs)]$(pound)![feature(no_core)]$(pound)![no_core]' | RUSTC_BOOTSTRAP=1\
+	$(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null --target=%,$(2)) $(3)\
 	--crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4))
 
 # rustc-option

scripts/generate_rust_analyzer.py

@@ -112,6 +112,12 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
         cfg=["kernel"],
     )
 
+    append_crate(
+        "ffi",
+        srctree / "rust" / "ffi.rs",
+        ["core", "compiler_builtins"],
+    )
+
     def append_crate_with_generated(
         display_name,
         deps,
@@ -131,9 +137,9 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
             "exclude_dirs": [],
         }
 
-    append_crate_with_generated("bindings", ["core"])
-    append_crate_with_generated("uapi", ["core"])
-    append_crate_with_generated("kernel", ["core", "macros", "build_error", "pin_init", "bindings", "uapi"])
+    append_crate_with_generated("bindings", ["core", "ffi"])
+    append_crate_with_generated("uapi", ["core", "ffi"])
+    append_crate_with_generated("kernel", ["core", "macros", "build_error", "pin_init", "ffi", "bindings", "uapi"])
 
     def is_root_crate(build_file, target):
         try:

tools/objtool/check.c

@@ -225,6 +225,7 @@ static bool is_rust_noreturn(const struct symbol *func)
 	       str_ends_with(func->name, "_4core9panicking14panic_nounwind")				||
 	       str_ends_with(func->name, "_4core9panicking18panic_bounds_check")			||
 	       str_ends_with(func->name, "_4core9panicking19assert_failed_inner")			||
+	       str_ends_with(func->name, "_4core9panicking30panic_null_pointer_dereference")		||
 	       str_ends_with(func->name, "_4core9panicking36panic_misaligned_pointer_dereference")	||
 	       strstr(func->name, "_4core9panicking13assert_failed")					||
 	       strstr(func->name, "_4core9panicking11panic_const24panic_const_")			||