On Tue, 15 Oct 2024 06:14:58 PDT (-0700), aliceryhl@google.com wrote:
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) <peterz@infradead.org>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
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 | 35 +++++++++--------------
5 files changed, 73 insertions(+), 62 deletions(-)
[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_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 @@
#define JUMP_LABEL_NOP_SIZE 4
+#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 key,
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);
return false;@@ -38,21 +45,20 @@ static __always_inline bool arch_static_branch(struct static_key * const key,
return true;
}
+#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 * const 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);
return false;
Acked-by: Palmer Dabbelt <redacted> # RISC-V