c4e5c229b6
Currently kernel build fails under clang if jump labels are enabled. The problem is "X" constraint usage "Any operand whatsoever is allowed", for which clang produces the following: .pushsection __jump_table,"aw" .balign 8 .long 0b-.,.Ltmp577-. .quad %r0+0-. # %r0 is not allowed here .popsection Under gcc constraints "X" or "jdd" (gcc > 9) are used for static keys. Ideally, we'd have used "i" for gcc, but it doesn't work in all cases with -fPIC code. This is gcc-specific problem that doesn't exist in llvm. Since clang does not have "jdd" simply always use "i" constraint for it. Suggested-by: Ulrich Weigand <ulrich.weigand@de.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
55 lines
1.4 KiB
C
55 lines
1.4 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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#ifndef __ASSEMBLY__
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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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#define JUMP_LABEL_NOP_OFFSET 2
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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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/*
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* We use a brcl 0,2 instruction for jump labels at compile time so it
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* can be easily distinguished from a hotpatch generated instruction.
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*/
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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_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
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".pushsection __jump_table,\"aw\"\n"
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".balign 8\n"
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".long 0b-.,%l[label]-.\n"
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".quad %0+%1-.\n"
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".popsection\n"
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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_volatile_goto("0: brcl 15,%l[label]\n"
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".pushsection __jump_table,\"aw\"\n"
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".balign 8\n"
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".long 0b-.,%l[label]-.\n"
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".quad %0+%1-.\n"
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".popsection\n"
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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 /* __ASSEMBLY__ */
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#endif
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