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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-08-14 06:22:34 +02:00
Jan Polensky
6900bec59d
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>
61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_S390_JUMP_LABEL_H
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#define _ASM_S390_JUMP_LABEL_H
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#define HAVE_JUMP_LABEL_BATCH
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#ifndef __ASSEMBLER__
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#include <linux/types.h>
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#include <linux/stringify.h>
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#define JUMP_LABEL_NOP_SIZE 6
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#ifdef CONFIG_CC_IS_CLANG
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#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "i"
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#elif __GNUC__ < 9
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#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "X"
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#else
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#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"
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#endif
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#define ARCH_JUMP_TABLE_ENTRY(key, label, local_label) \
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".pushsection __jump_table,\"aw\"\n" \
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".balign 8\n" \
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".long " local_label "-.," label "-.\n" \
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".quad " key "-.\n" \
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".popsection\n"
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/*
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* We use a brcl 0,<offset> instruction for jump labels so it
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* can be easily distinguished from a hotpatch generated instruction.
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*/
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#define ARCH_STATIC_BRANCH_ASM(key, label) \
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"0: brcl 0," label "\n" \
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ARCH_JUMP_TABLE_ENTRY(key, label, "0b")
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#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \
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"0: brcl 15," label "\n" \
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ARCH_JUMP_TABLE_ENTRY(key, label, "0b")
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static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
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{
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asm goto(ARCH_STATIC_BRANCH_ASM("%0+%1", "%l[label]")
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: : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
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return false;
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label:
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return true;
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}
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static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
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{
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asm goto(ARCH_STATIC_BRANCH_JUMP_ASM("%0+%1", "%l[label]")
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: : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
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return false;
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label:
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return true;
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}
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#endif /* __ASSEMBLER__ */
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#endif
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