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Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Add just enough support for static key so that we can use it from tracepoints. Tracepoints rely on `static_key_false` even though it is deprecated, so we add the same functionality to Rust. This patch only provides a generic implementation without code patching (matching the one used when CONFIG_JUMP_LABEL is disabled). Later patches add support for inline asm implementations that use runtime patching. When CONFIG_JUMP_LABEL is unset, `static_key_count` is a static inline function, so a Rust helper is defined for `static_key_count` in this case. If Rust is compiled with LTO, this call should get inlined. The helper can be eliminated once we have the necessary inline asm to make atomic operations from Rust. Signed-off-by: Alice Ryhl --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 9 +++++++++ rust/kernel/jump_label.rs | 29 +++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 4 files changed, 40 insertions(+) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index b940a5777330..8fd092e1b809 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers.c b/rust/helpers.c index 92d3c03ae1bd..5a9bf5209cd8 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -133,6 +134,14 @@ bool rust_helper_refcount_dec_and_test(refcount_t *r) } EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); =20 +#ifndef CONFIG_JUMP_LABEL +int rust_helper_static_key_count(struct static_key *key) +{ + return static_key_count(key); +} +EXPORT_SYMBOL_GPL(rust_helper_static_key_count); +#endif + __force void *rust_helper_ERR_PTR(long err) { return ERR_PTR(err); diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs new file mode 100644 index 000000000000..011e1fc1d19a --- /dev/null +++ b/rust/kernel/jump_label.rs @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Logic for static keys. +//! +//! C header: [`include/linux/jump_label.h`](srctree/include/linux/jump_la= bel.h). + +/// Branch based on a static key. +/// +/// Takes three arguments: +/// +/// * `key` - the path to the static variable containing the `static_key`. +/// * `keytyp` - the type of `key`. +/// * `field` - the name of the field of `key` that contains the `static_k= ey`. +/// +/// # Safety +/// +/// The macro must be used with a real static key defined by C. +#[macro_export] +macro_rules! static_key_false { + ($key:path, $keytyp:ty, $field:ident) =3D> {{ + let _key: *const $keytyp =3D ::core::ptr::addr_of!($key); + let _key: *const $crate::bindings::static_key =3D ::core::ptr::add= r_of!((*_key).$field); + + $crate::bindings::static_key_count(_key.cast_mut()) > 0 + }}; +} +pub use static_key_false; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 274bdc1b0a82..91af9f75d121 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -36,6 +36,7 @@ pub mod firmware; pub mod init; pub mod ioctl; +pub mod jump_label; 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Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl , Carlos Llamas Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Make it possible to have Rust code call into tracepoints defined by C code. It is still required that the tracepoint is declared in a C header, and that this header is included in the input to bindgen. Instead of calling __DO_TRACE directly, the exported rust_do_trace_ function calls an inline helper function. This is because the `cond` argument does not exist at the callsite of DEFINE_RUST_DO_TRACE. __DECLARE_TRACE always emits an inline static and an extern declaration that is only used when CREATE_RUST_TRACE_POINTS is set. These should not end up in the final binary so it is not a problem that they sometimes are emitted without a user. Reviewed-by: Carlos Llamas Reviewed-by: Gary Guo Signed-off-by: Alice Ryhl --- include/linux/tracepoint.h | 22 +++++++++++++++++- include/trace/define_trace.h | 12 ++++++++++ rust/bindings/bindings_helper.h | 1 + rust/kernel/lib.rs | 1 + rust/kernel/tracepoint.rs | 49 +++++++++++++++++++++++++++++++++++++= ++++ 5 files changed, 84 insertions(+), 1 deletion(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 6be396bb4297..5042ca588e41 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -237,6 +237,18 @@ static inline struct tracepoint *tracepoint_ptr_deref(= tracepoint_ptr_t *p) #define __DECLARE_TRACE_RCU(name, proto, args, cond) #endif =20 +/* + * Declare an exported function that Rust code can call to trigger this + * tracepoint. This function does not include the static branch; that is d= one + * in Rust to avoid a function call when the tracepoint is disabled. + */ +#define DEFINE_RUST_DO_TRACE(name, proto, args) +#define __DEFINE_RUST_DO_TRACE(name, proto, args) \ + notrace void rust_do_trace_##name(proto) \ + { \ + __rust_do_trace_##name(args); \ + } + /* * Make sure the alignment of the structure in the __tracepoints section w= ill * not add unwanted padding between the beginning of the section and the @@ -252,6 +264,13 @@ static inline struct tracepoint *tracepoint_ptr_deref(= tracepoint_ptr_t *p) extern int __traceiter_##name(data_proto); \ DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \ extern struct tracepoint __tracepoint_##name; \ + extern void rust_do_trace_##name(proto); \ + static inline void __rust_do_trace_##name(proto) \ + { \ + __DO_TRACE(name, \ + TP_ARGS(args), \ + TP_CONDITION(cond), 0); \ + } \ static inline void trace_##name(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ @@ -336,7 +355,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) void __probestub_##_name(void *__data, proto) \ { \ } \ - DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); + DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); \ + DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args)) =20 #define DEFINE_TRACE(name, proto, args) \ DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args)); diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h index 00723935dcc7..8159294c2041 100644 --- a/include/trace/define_trace.h +++ b/include/trace/define_trace.h @@ -72,6 +72,13 @@ #define DECLARE_TRACE(name, proto, args) \ DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) =20 +/* If requested, create helpers for calling these tracepoints from Rust. */ +#ifdef CREATE_RUST_TRACE_POINTS +#undef DEFINE_RUST_DO_TRACE +#define DEFINE_RUST_DO_TRACE(name, proto, args) \ + __DEFINE_RUST_DO_TRACE(name, PARAMS(proto), PARAMS(args)) +#endif + #undef TRACE_INCLUDE #undef __TRACE_INCLUDE =20 @@ -129,6 +136,11 @@ # undef UNDEF_TRACE_INCLUDE_PATH #endif =20 +#ifdef CREATE_RUST_TRACE_POINTS +# undef DEFINE_RUST_DO_TRACE +# define DEFINE_RUST_DO_TRACE(name, proto, args) +#endif + /* We may be processing more files */ #define CREATE_TRACE_POINTS =20 diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index 8fd092e1b809..fc6f94729789 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -20,6 +20,7 @@ #include #include #include +#include #include #include =20 diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 91af9f75d121..d00a44b000b6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -51,6 +51,7 @@ pub mod sync; pub mod task; pub mod time; +pub mod tracepoint; pub mod types; pub mod uaccess; pub mod workqueue; diff --git a/rust/kernel/tracepoint.rs b/rust/kernel/tracepoint.rs new file mode 100644 index 000000000000..cf2d9ad15912 --- /dev/null +++ b/rust/kernel/tracepoint.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Logic for tracepoints. + +/// Declare the Rust entry point for a tracepoint. +/// +/// This macro generates an unsafe function that calls into C, and its saf= ety requirements will be +/// whatever the relevant C code requires. 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Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable This updates the Rust printing sample to invoke a tracepoint. This ensures that we have a user in-tree from the get-go even though the patch is being merged before its real user. Signed-off-by: Alice Ryhl --- MAINTAINERS | 1 + include/trace/events/rust_sample.h | 31 +++++++++++++++++++++++++++++++ rust/bindings/bindings_helper.h | 1 + samples/rust/Makefile | 3 ++- samples/rust/rust_print.rs | 18 ++++++++++++++++++ samples/rust/rust_print_events.c | 8 ++++++++ 6 files changed, 61 insertions(+), 1 deletion(-) diff --git a/MAINTAINERS b/MAINTAINERS index f328373463b0..1acf5bfddfc4 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -19922,6 +19922,7 @@ C: zulip://rust-for-linux.zulipchat.com P: https://rust-for-linux.com/contributing T: git https://github.com/Rust-for-Linux/linux.git rust-next F: Documentation/rust/ +F: include/trace/events/rust_sample.h F: rust/ F: samples/rust/ F: scripts/*rust* diff --git a/include/trace/events/rust_sample.h b/include/trace/events/rust= _sample.h new file mode 100644 index 000000000000..dbc80ca2e465 --- /dev/null +++ b/include/trace/events/rust_sample.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Tracepoints for `samples/rust/rust_print.rs`. + * + * Copyright (C) 2024 Google, Inc. + */ + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM rust_sample + +#if !defined(_RUST_SAMPLE_TRACE_H) || defined(TRACE_HEADER_MULTI_READ) +#define _RUST_SAMPLE_TRACE_H + +#include + +TRACE_EVENT(rust_sample_loaded, + TP_PROTO(int magic_number), + TP_ARGS(magic_number), + TP_STRUCT__entry( + __field(int, magic_number) + ), + TP_fast_assign( + __entry->magic_number =3D magic_number; + ), + TP_printk("magic=3D%d", __entry->magic_number) +); + +#endif /* _RUST_SAMPLE_TRACE_H */ + +/* This part must be outside protection */ +#include diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index fc6f94729789..fe97256afe65 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -23,6 +23,7 @@ #include #include #include +#include =20 /* `bindgen` gets confused at certain things. */ const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN =3D ARCH_SLAB_MINALIGN; diff --git a/samples/rust/Makefile b/samples/rust/Makefile index 03086dabbea4..f29280ec4820 100644 --- a/samples/rust/Makefile +++ b/samples/rust/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 +ccflags-y +=3D -I$(src) # needed for trace events =20 obj-$(CONFIG_SAMPLE_RUST_MINIMAL) +=3D rust_minimal.o -obj-$(CONFIG_SAMPLE_RUST_PRINT) +=3D rust_print.o +obj-$(CONFIG_SAMPLE_RUST_PRINT) +=3D rust_print.o rust_print_events.o =20 subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS) +=3D hostprogs diff --git a/samples/rust/rust_print.rs b/samples/rust/rust_print.rs index 6eabb0d79ea3..6d14b08cac1c 100644 --- a/samples/rust/rust_print.rs +++ b/samples/rust/rust_print.rs @@ -69,6 +69,8 @@ fn init(_module: &'static ThisModule) -> Result { =20 arc_print()?; 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Fri, 16 Aug 2024 04:08:28 -0700 (PDT) Date: Fri, 16 Aug 2024 11:07:41 +0000 In-Reply-To: <20240816-tracepoint-v7-0-d609b916b819@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240816-tracepoint-v7-0-d609b916b819@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=9372; i=aliceryhl@google.com; h=from:subject:message-id; bh=NCijnrFVATFS0Jb3tHGcAM6xeWG4d78Efm1z0mpVoWk=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmvzMe9Qsdoi2s5idl4F4MxYG7XPSkLKE9NF+bM rMy4FJDPcSJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZr8zHgAKCRAEWL7uWMY5 RhosD/9CWTEswpwOORoAMxjPJfw2m2DPxDoZQ5oIsQ9CKyp1rwE9hTQCVA/fGaVVTShlLkjoK+q NZyUmLLmYc315k1Bu529ZqzCoF4zJSW/Sa1x9thP9lTL7p4alaSIfPqRun9jtok+SQrc1Wo3uRM hS0BX3NmrGLzIW3afnMh0PnwGYAnSMTKP+s8oqDoz0z3GVE8xDK+eeD4ebneMeBwBpsBHVg9l+f ljSZ3aWPRWjNyM2K96CKfmt2zYEnz5nfYpRi434H8SPSxgWFLU2LLHsXGGyJmCytCLP6Cxnld9E OhFUnVogiVcV6pTrK5xRpOYTYB4PvzlXFzRMSq5uqjH+gzojo8oeZ535Wx0F0Ec9GxofWQ3OIsE 9lFjxyJOBeAPt57y3Z6TrvG4W6mMCKJB9unla7TRlVvkM2o0x+oMTXrm+7lhk4GPKZt55eZf0/s akOZmHVyHA/81TpTvknraSwXVnLI4v4Fb82bg7S36ND7dyYcYPp3znFC4OXE2nUG9+A30SUVrU/ MgKJVKIlF9vmUZCWfgOnmdCBFzl8UpXvAGeLYB5SFCu29cdOR2xKZHBQSYHJvFMan9ehxfOKO1a CE4TXfhDn+sPoqlVSEZ3m2OW0aIlKNwsEZ8CfapSA8WUVdmx6B0W1LY+oxkB0BDoUxiaMDwPW2Z xHo/VQDSQIKngSg== X-Mailer: b4 0.13.0 Message-ID: <20240816-tracepoint-v7-4-d609b916b819@google.com> Subject: [PATCH v7 4/5] jump_label: adjust inline asm to be consistent From: Alice Ryhl To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg Cc: linux-trace-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , linux-arch@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To avoid duplication of inline asm between C and Rust, we need to import the inline asm from the relevant `jump_label.h` header into Rust. To make that easier, this patch updates the header files to expose the inline asm via a new ARCH_STATIC_BRANCH_ASM macro. The header files are all updated to define a ARCH_STATIC_BRANCH_ASM that takes the same arguments in a consistent order so that Rust can use the same logic for every architecture. Suggested-by: Peter Zijlstra (Intel) Acked-by: Peter Zijlstra (Intel) Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Signed-off-by: Alice Ryhl --- arch/arm/include/asm/jump_label.h | 14 +++++---- arch/arm64/include/asm/jump_label.h | 20 ++++++++----- arch/loongarch/include/asm/jump_label.h | 16 +++++++---- arch/riscv/include/asm/jump_label.h | 50 ++++++++++++++++++-----------= ---- arch/x86/include/asm/jump_label.h | 38 ++++++++++--------------- 5 files changed, 75 insertions(+), 63 deletions(-) diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_= label.h index e4eb54f6cd9f..a35aba7f548c 100644 --- a/arch/arm/include/asm/jump_label.h +++ b/arch/arm/include/asm/jump_label.h @@ -9,13 +9,17 @@ =20 #define JUMP_LABEL_NOP_SIZE 4 =20 +/* This macro is also expanded on the Rust side. */ +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "1:\n\t" \ + WASM(nop) "\n\t" \ + ".pushsection __jump_table, \"aw\"\n\t" \ + ".word 1b, " label ", " key "\n\t" \ + ".popsection\n\t" \ + static __always_inline bool arch_static_branch(struct static_key *key, boo= l branch) { - asm goto("1:\n\t" - WASM(nop) "\n\t" - ".pushsection __jump_table, \"aw\"\n\t" - ".word 1b, %l[l_yes], %c0\n\t" - ".popsection\n\t" + asm goto(ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]") : : "i" (&((char *)key)[branch]) : : l_yes); =20 return false; diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/j= ump_label.h index a0a5bbae7229..424ed421cd97 100644 --- a/arch/arm64/include/asm/jump_label.h +++ b/arch/arm64/include/asm/jump_label.h @@ -19,10 +19,14 @@ #define JUMP_TABLE_ENTRY(key, label) \ ".pushsection __jump_table, \"aw\"\n\t" \ ".align 3\n\t" \ - ".long 1b - ., %l["#label"] - .\n\t" \ - ".quad %c0 - .\n\t" \ - ".popsection\n\t" \ - : : "i"(key) : : label + ".long 1b - ., " label " - .\n\t" \ + ".quad " key " - .\n\t" \ + ".popsection\n\t" + +/* This macro is also expanded on the Rust side. */ +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "1: nop\n\t" \ + JUMP_TABLE_ENTRY(key, label) =20 static __always_inline bool arch_static_branch(struct static_key * const k= ey, const bool branch) @@ -30,8 +34,8 @@ static __always_inline bool arch_static_branch(struct sta= tic_key * const key, char *k =3D &((char *)key)[branch]; =20 asm goto( - "1: nop \n\t" - JUMP_TABLE_ENTRY(k, l_yes) + ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]") + : : "i"(k) : : l_yes ); =20 return false; @@ -43,9 +47,11 @@ static __always_inline bool arch_static_branch_jump(stru= ct static_key * const ke const bool branch) { char *k =3D &((char *)key)[branch]; + asm goto( "1: b %l[l_yes] \n\t" - JUMP_TABLE_ENTRY(k, l_yes) + JUMP_TABLE_ENTRY("%c0", "%l[l_yes]") + : : "i"(k) : : l_yes ); return false; l_yes: diff --git a/arch/loongarch/include/asm/jump_label.h b/arch/loongarch/inclu= de/asm/jump_label.h index 29acfe3de3fa..8a924bd69d19 100644 --- a/arch/loongarch/include/asm/jump_label.h +++ b/arch/loongarch/include/asm/jump_label.h @@ -13,18 +13,22 @@ =20 #define JUMP_LABEL_NOP_SIZE 4 =20 -#define JUMP_TABLE_ENTRY \ +/* This macro is also expanded on the Rust side. */ +#define JUMP_TABLE_ENTRY(key, label) \ ".pushsection __jump_table, \"aw\" \n\t" \ ".align 3 \n\t" \ - ".long 1b - ., %l[l_yes] - . \n\t" \ - ".quad %0 - . \n\t" \ + ".long 1b - ., " label " - . \n\t" \ + ".quad " key " - . \n\t" \ ".popsection \n\t" =20 +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "1: nop \n\t" \ + JUMP_TABLE_ENTRY(key, label) + static __always_inline bool arch_static_branch(struct static_key * const k= ey, const bool branch) { asm goto( - "1: nop \n\t" - JUMP_TABLE_ENTRY + ARCH_STATIC_BRANCH_ASM("%0", "%l[l_yes]") : : "i"(&((char *)key)[branch]) : : l_yes); =20 return false; @@ -37,7 +41,7 @@ static __always_inline bool arch_static_branch_jump(struc= t static_key * const ke { asm goto( "1: b %l[l_yes] \n\t" - JUMP_TABLE_ENTRY + JUMP_TABLE_ENTRY("%0", "%l[l_yes]") : : "i"(&((char *)key)[branch]) : : l_yes); =20 return false; diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/j= ump_label.h index 1c768d02bd0c..87a71cc6d146 100644 --- a/arch/riscv/include/asm/jump_label.h +++ b/arch/riscv/include/asm/jump_label.h @@ -16,21 +16,28 @@ =20 #define JUMP_LABEL_NOP_SIZE 4 =20 +#define JUMP_TABLE_ENTRY(key, label) \ + ".pushsection __jump_table, \"aw\" \n\t" \ + ".align " RISCV_LGPTR " \n\t" \ + ".long 1b - ., " label " - . \n\t" \ + "" RISCV_PTR " " key " - . \n\t" \ + ".popsection \n\t" + +/* This macro is also expanded on the Rust side. */ +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + " .align 2 \n\t" \ + " .option push \n\t" \ + " .option norelax \n\t" \ + " .option norvc \n\t" \ + "1: nop \n\t" \ + " .option pop \n\t" \ + JUMP_TABLE_ENTRY(key, label) + static __always_inline bool arch_static_branch(struct static_key * const k= ey, const bool branch) { asm goto( - " .align 2 \n\t" - " .option push \n\t" - " .option norelax \n\t" - " .option norvc \n\t" - "1: nop \n\t" - " .option pop \n\t" - " .pushsection __jump_table, \"aw\" \n\t" - " .align " RISCV_LGPTR " \n\t" - " .long 1b - ., %l[label] - . \n\t" - " " RISCV_PTR " %0 - . \n\t" - " .popsection \n\t" + ARCH_STATIC_BRANCH_ASM("%0", "%l[label]") : : "i"(&((char *)key)[branch]) : : label); =20 return false; @@ -38,21 +45,20 @@ static __always_inline bool arch_static_branch(struct s= tatic_key * const key, return true; } =20 +#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \ + " .align 2 \n\t" \ + " .option push \n\t" \ + " .option norelax \n\t" \ + " .option norvc \n\t" \ + "1: j " label " \n\t" \ + " .option pop \n\t" \ + JUMP_TABLE_ENTRY(key, label) + static __always_inline bool arch_static_branch_jump(struct static_key * co= nst key, const bool branch) { asm goto( - " .align 2 \n\t" - " .option push \n\t" - " .option norelax \n\t" - " .option norvc \n\t" - "1: j %l[label] \n\t" - " .option pop \n\t" - " .pushsection __jump_table, \"aw\" \n\t" - " .align " RISCV_LGPTR " \n\t" - " .long 1b - ., %l[label] - . \n\t" - " " RISCV_PTR " %0 - . \n\t" - " .popsection \n\t" + ARCH_STATIC_BRANCH_JUMP_ASM("%0", "%l[label]") : : "i"(&((char *)key)[branch]) : : label); =20 return false; diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_= label.h index cbbef32517f0..fb79fa1cf70a 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -12,49 +12,41 @@ #include #include =20 -#define JUMP_TABLE_ENTRY \ +#define JUMP_TABLE_ENTRY(key, label) \ ".pushsection __jump_table, \"aw\" \n\t" \ _ASM_ALIGN "\n\t" \ ".long 1b - . \n\t" \ - ".long %l[l_yes] - . \n\t" \ - _ASM_PTR "%c0 + %c1 - .\n\t" \ + ".long " label " - . \n\t" \ + _ASM_PTR " " key " - . \n\t" \ ".popsection \n\t" =20 +/* This macro is also expanded on the Rust side. */ #ifdef CONFIG_HAVE_JUMP_LABEL_HACK - -static __always_inline bool arch_static_branch(struct static_key *key, boo= l branch) -{ - asm goto("1:" - "jmp %l[l_yes] # objtool NOPs this \n\t" - JUMP_TABLE_ENTRY - : : "i" (key), "i" (2 | branch) : : l_yes); - - return false; -l_yes: - return true; -} - +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "1: jmp " label " # objtool NOPs this \n\t" \ + JUMP_TABLE_ENTRY(key, label) #else /* !CONFIG_HAVE_JUMP_LABEL_HACK */ +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "1: .byte " __stringify(BYTES_NOP5) "\n\t" \ + JUMP_TABLE_ENTRY(key, label) +#endif /* CONFIG_HAVE_JUMP_LABEL_HACK */ =20 static __always_inline bool arch_static_branch(struct static_key * const k= ey, const bool branch) { - asm goto("1:" - ".byte " __stringify(BYTES_NOP5) "\n\t" - JUMP_TABLE_ENTRY - : : "i" (key), "i" (branch) : : l_yes); + int hack_bit =3D IS_ENABLED(CONFIG_HAVE_JUMP_LABEL_HACK) ? 2 : 0; + asm goto(ARCH_STATIC_BRANCH_ASM("%c0 + %c1", "%l[l_yes]") + : : "i" (key), "i" (hack_bit | branch) : : l_yes); =20 return false; l_yes: return true; } =20 -#endif /* CONFIG_HAVE_JUMP_LABEL_HACK */ - static __always_inline bool arch_static_branch_jump(struct static_key * co= nst key, const bool branch) { asm goto("1:" "jmp %l[l_yes]\n\t" - JUMP_TABLE_ENTRY + JUMP_TABLE_ENTRY("%c0 + %c1", "%l[l_yes]") : : "i" (key), "i" (branch) : : l_yes); 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a=openpgp-sha256; l=8293; i=aliceryhl@google.com; h=from:subject:message-id; bh=eqhw7ynCkyqRTBYr25akl57ew2XiOS3KqCJmdV1FKbU=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmvzMfcXLQpUYwewTAhsSdNWmokGVZvVA8EJG// aC62ZEklIeJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZr8zHwAKCRAEWL7uWMY5 RoZHD/9KDdVUP3BBgQ8pSdZ3eJOAhx3HVdp/bSXL+MXcHSRDrSDIsJwxRWZS60hr6EtwT6AurLn UPla/AqD6Oay++sCbgaH8VLUixf+Tbvt7yuogvGmQZWZNTHWTJDEc7r7qZQ59/R1jI/PupK3IZ5 WAKHPbXBDCc1TSWmWKgCFLofieTPsG6pwHc+YnT24Cvn0VDvTF1OGXGhR1ekG2wj4rGEoIzzJj8 s0exuGT7OLyWPcxq2VBhvcWcxbplSMH3JfAhlhEIZ42Cf9mKPcSIZZYz+6VFdiCQDNMXfuP3B9J 8KwdUNCYWQpJaNnDIQUJuUGCmngfihTxD8GOr/qT2p2xdPfLiSmaXHlmNBJ7+xdHCwFXZbaq6KF BbD9z1HOS3dl2AdojQ32VfZPxSruVbQpUqw5oQpLhm2qZafOgiQBCJtxBSJm8Q/XmXjDSu9qu0F iPWOoS0lzTbWgbZN5Aje/U+aRPjdSm2CvTOXMzPyf/FsfsvBnpDucB5mAJffbfo+3yYunvJBkCr rDQbQiObpHhbXbEBg4y6KMY83Load++HUKIJRkrniazwGFJnMUFvqMrN/Hk2gQuAQNbp8fvd93b +NGHq0nYPgGFl3/jed1TAWrgBirpddAnt31c3ls16hHqlKFV/OG1ygnWvnSfgYhxUF/djO7+BZx 9GKLEuK+9ku6UiA== X-Mailer: b4 0.13.0 Message-ID: <20240816-tracepoint-v7-5-d609b916b819@google.com> Subject: [PATCH v7 5/5] rust: add arch_static_branch From: Alice Ryhl To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg Cc: linux-trace-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , linux-arch@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To allow the Rust implementation of static_key_false to use runtime code patching instead of the generic implementation, pull in the relevant inline assembly from the jump_label.h header by running the C preprocessor on a .rs.S file. Build rules are added for .rs.S files. Since the relevant inline asm has been adjusted to export the inline asm via the ARCH_STATIC_BRANCH_ASM macro in a consistent way, the Rust side does not need architecture specific code to pull in the asm. It is not possible to use the existing C implementation of arch_static_branch via a Rust helper because it passes the argument `key` to inline assembly as an 'i' parameter. Any attempt to add a C helper for this function will fail to compile because the value of `key` must be known at compile-time. Suggested-by: Peter Zijlstra (Intel) Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Signed-off-by: Alice Ryhl --- rust/Makefile | 5 ++- rust/kernel/.gitignore | 3 ++ rust/kernel/arch_static_branch_asm.rs.S | 7 ++++ rust/kernel/jump_label.rs | 64 +++++++++++++++++++++++++++++= +++- rust/kernel/lib.rs | 30 ++++++++++++++++ scripts/Makefile.build | 9 ++++- 6 files changed, 115 insertions(+), 3 deletions(-) diff --git a/rust/Makefile b/rust/Makefile index 199e0db67962..277fcef656b8 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -14,6 +14,8 @@ CFLAGS_REMOVE_helpers.o =3D -Wmissing-prototypes -Wmissin= g-declarations always-$(CONFIG_RUST) +=3D libmacros.so no-clean-files +=3D libmacros.so =20 +always-$(subst y,$(CONFIG_RUST),$(CONFIG_JUMP_LABEL)) +=3D kernel/arch_sta= tic_branch_asm.rs + always-$(CONFIG_RUST) +=3D bindings/bindings_generated.rs bindings/binding= s_helpers_generated.rs obj-$(CONFIG_RUST) +=3D alloc.o bindings.o kernel.o always-$(CONFIG_RUST) +=3D exports_alloc_generated.h exports_bindings_gene= rated.h \ @@ -409,7 +411,8 @@ $(obj)/uapi.o: $(src)/uapi/lib.rs \ $(obj)/kernel.o: private rustc_target_flags =3D --extern alloc \ --extern build_error --extern macros --extern bindings --extern uapi $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \ - $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE + $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o \ + $(obj)/kernel/arch_static_branch_asm.rs FORCE +$(call if_changed_rule,rustc_library) =20 endif # CONFIG_RUST diff --git a/rust/kernel/.gitignore b/rust/kernel/.gitignore new file mode 100644 index 000000000000..d082731007c6 --- /dev/null +++ b/rust/kernel/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +/arch_static_branch_asm.rs diff --git a/rust/kernel/arch_static_branch_asm.rs.S b/rust/kernel/arch_sta= tic_branch_asm.rs.S new file mode 100644 index 000000000000..9e373d4f7567 --- /dev/null +++ b/rust/kernel/arch_static_branch_asm.rs.S @@ -0,0 +1,7 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +// Cut here. + +::kernel::concat_literals!(ARCH_STATIC_BRANCH_ASM("{symb} + {off} + {branc= h}", "{l_yes}")) diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs index 011e1fc1d19a..7757e4f8e85e 100644 --- a/rust/kernel/jump_label.rs +++ b/rust/kernel/jump_label.rs @@ -23,7 +23,69 @@ macro_rules! static_key_false { let _key: *const $keytyp =3D ::core::ptr::addr_of!($key); let _key: *const $crate::bindings::static_key =3D ::core::ptr::add= r_of!((*_key).$field); =20 - $crate::bindings::static_key_count(_key.cast_mut()) > 0 + #[cfg(not(CONFIG_JUMP_LABEL))] + { + $crate::bindings::static_key_count(_key.cast_mut()) > 0 + } + + #[cfg(CONFIG_JUMP_LABEL)] + $crate::jump_label::arch_static_branch! { $key, $keytyp, $field, f= alse } }}; } pub use static_key_false; + +/// Assert that the assembly block evaluates to a string literal. +#[cfg(CONFIG_JUMP_LABEL)] +const _: &str =3D include!("arch_static_branch_asm.rs"); + +#[macro_export] +#[doc(hidden)] +#[cfg(CONFIG_JUMP_LABEL)] +#[cfg(not(CONFIG_HAVE_JUMP_LABEL_HACK))] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + $crate::asm!( + include!(concat!(env!("SRCTREE"), "/rust/kernel/arch_static_br= anch_asm.rs")); + l_yes =3D label { + break 'my_label true; + }, + symb =3D sym $key, + off =3D const ::core::mem::offset_of!($keytyp, $field), + branch =3D const $crate::jump_label::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +#[macro_export] +#[doc(hidden)] +#[cfg(CONFIG_JUMP_LABEL)] +#[cfg(CONFIG_HAVE_JUMP_LABEL_HACK)] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + $crate::asm!( + include!(concat!(env!("SRCTREE"), "/rust/kernel/arch_static_br= anch_asm.rs")); + l_yes =3D label { + break 'my_label true; + }, + symb =3D sym $key, + off =3D const ::core::mem::offset_of!($keytyp, $field), + branch =3D const 2 | $crate::jump_label::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +#[cfg(CONFIG_JUMP_LABEL)] +pub use arch_static_branch; + +/// A helper used by inline assembly to pass a boolean to as a `const` par= ameter. +/// +/// Using this function instead of a cast lets you assert that the input i= s a boolean, and not some +/// other type that can also be cast to an integer. +#[doc(hidden)] +pub const fn bool_to_int(b: bool) -> i32 { + b as i32 +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index d00a44b000b6..9e9b95ab6966 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -145,3 +145,33 @@ macro_rules! container_of { ptr.sub(offset) as *const $type }} } + +/// Helper for `.rs.S` files. +#[doc(hidden)] +#[macro_export] +macro_rules! concat_literals { + ($( $asm:literal )* ) =3D> { + ::core::concat!($($asm),*) + }; +} + +/// Wrapper around `asm!` that uses at&t syntax on x86. +// Uses a semicolon to avoid parsing ambiguities, even though this does no= t match native `asm!` +// syntax. +#[cfg(target_arch =3D "x86_64")] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) =3D> { + ::core::arch::asm!( $($asm)*, options(att_syntax), $($rest)* ) + }; +} + +/// Wrapper around `asm!` that uses at&t syntax on x86. +// For non-x86 arches we just pass through to `asm!`. +#[cfg(not(target_arch =3D "x86_64"))] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) =3D> { + ::core::arch::asm!( $($asm)*, $($rest)* ) + }; +} diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 72b1232b1f7d..59fe83fba647 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -263,12 +263,13 @@ $(obj)/%.lst: $(obj)/%.c FORCE # Compile Rust sources (.rs) # ------------------------------------------------------------------------= --- =20 -rust_allowed_features :=3D new_uninit +rust_allowed_features :=3D asm_const,asm_goto,new_uninit =20 # `--out-dir` is required to avoid temporaries being created by `rustc` in= the # current working directory, which may be not accessible in the out-of-tree # modules case. rust_common_cmd =3D \ + SRCTREE=3D$(abspath $(srctree)) \ RUST_MODFILE=3D$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \ -Zallow-features=3D$(rust_allowed_features) \ -Zcrate-attr=3Dno_std \ @@ -318,6 +319,12 @@ quiet_cmd_rustc_ll_rs =3D $(RUSTC_OR_CLIPPY_QUIET) $(q= uiet_modtag) $@ $(obj)/%.ll: $(obj)/%.rs FORCE +$(call if_changed_dep,rustc_ll_rs) =20 +quiet_cmd_rustc_rs_rs_S =3D RSCPP $(quiet_modtag) $@ + cmd_rustc_rs_rs_S =3D $(CPP) $(c_flags) -xc -C -P $< | sed '1,/^\/\/= Cut here.$$/d' >$@ + +$(obj)/%.rs: $(obj)/%.rs.S FORCE + +$(call if_changed_dep,rustc_rs_rs_S) + # Compile assembler sources (.S) # ------------------------------------------------------------------------= --- =20 --=20 2.46.0.184.g6999bdac58-goog