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| author | Jan Polensky <japo@linux.ibm.com> | 2026-06-01 20:46:21 +0300 |
|---|---|---|
| committer | Alexander Gordeev <agordeev@linux.ibm.com> | 2026-06-10 17:25:13 +0300 |
| commit | 6900bec59d0f54dbb94d0799d204bcd44fbdb623 (patch) | |
| tree | cf3244e3c7549c52dcce9b74baf7e37bd7586e3b | |
| parent | 184b8dc8798987ffc889b5927c67b358f769a414 (diff) | |
| download | linux-6900bec59d0f54dbb94d0799d204bcd44fbdb623.tar.xz | |
s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and ARCH_STATIC_BRANCH_ASM macros
Rust static branch support needs the s390 jump label instruction sequence
and __jump_table emission in a reusable form. The current implementation
embeds the sequence directly in the C asm goto blocks, which cannot be
shared with Rust.
Introduce ARCH_STATIC_BRANCH_ASM and ARCH_STATIC_BRANCH_JUMP_ASM to
describe the brcl sequences for the likely-false and likely-true cases
and to emit the same __jump_table entries as before. Switch the existing
C helpers to use the new macros to avoid duplication without changing
the generated code.
Acked-by: Gary Guo <gary@garyguo.net>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/jump_label.h | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h index d9cbc18f6b2e..0e28c90dc242 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -19,19 +19,29 @@ #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd" #endif +#define ARCH_JUMP_TABLE_ENTRY(key, label, local_label) \ + ".pushsection __jump_table,\"aw\"\n" \ + ".balign 8\n" \ + ".long " local_label "-.," label "-.\n" \ + ".quad " key "-.\n" \ + ".popsection\n" + /* * We use a brcl 0,<offset> instruction for jump labels so it * can be easily distinguished from a hotpatch generated instruction. */ +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "0: brcl 0," label "\n" \ + ARCH_JUMP_TABLE_ENTRY(key, label, "0b") + +#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \ + "0: brcl 15," label "\n" \ + ARCH_JUMP_TABLE_ENTRY(key, label, "0b") + static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { - asm goto("0: brcl 0,%l[label]\n" - ".pushsection __jump_table,\"aw\"\n" - ".balign 8\n" - ".long 0b-.,%l[label]-.\n" - ".quad %0+%1-.\n" - ".popsection\n" - : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); + asm goto(ARCH_STATIC_BRANCH_ASM("%0+%1", "%l[label]") + : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); return false; label: return true; @@ -39,13 +49,8 @@ label: static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) { - asm goto("0: brcl 15,%l[label]\n" - ".pushsection __jump_table,\"aw\"\n" - ".balign 8\n" - ".long 0b-.,%l[label]-.\n" - ".quad %0+%1-.\n" - ".popsection\n" - : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); + asm goto(ARCH_STATIC_BRANCH_JUMP_ASM("%0+%1", "%l[label]") + : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); return false; label: return true; |