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s390/jump_label: use "i" constraint for clang

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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>
This commit is contained in:
Vasily Gorbik 2019-12-25 14:13:32 +01:00
parent ee09c91480
commit c4e5c229b6
1 changed files with 3 additions and 1 deletions
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4
arch/s390/include/asm/jump_label.h
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@ -10,7 +10,9 @@
#define JUMP_LABEL_NOP_SIZE 6
#define JUMP_LABEL_NOP_OFFSET 2
#if __GNUC__ < 9
#ifdef CONFIG_CC_IS_CLANG
#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "i"
#elif __GNUC__ < 9
#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "X"
#else
#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"