Commit f1069a87 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Josh Poimboeuf
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compiler.h: Avoid using inline asm operand modifiers 



The expansion of annotate_reachable/annotate_unreachable on s390 will
result in a compiler error if the __COUNTER__ value is high enough.
For example with "i" (154) the "%c0" operand of annotate_reachable
will be expanded to -102:

        -102:
        .pushsection .discard.reachable
        .long -102b - .
        .popsection

This is a quirk of the gcc backend for s390, it interprets the %c0
as a signed byte value. Avoid using operand modifiers in this case
by simply converting __COUNTER__ to string, with the same result,
but in an arch assembler independent way.

Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/patch-1.thread-1a26be.git-930d1b44844a.your-ad-here.call-01621428935-ext-2104@work.hours
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: linux-kernel@vger.kernel.org
parent 8852c552

include/linux/compiler.h

+14 −8
Original line number Diff line number Diff line
@@ -115,18 +115,24 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, 
 * The __COUNTER__ based labels are a hack to make each instance of the macros

 * unique, to convince GCC not to merge duplicate inline asm statements.

 */

#define annotate_reachable() ({						\

	asm volatile("%c0:\n\t"						\

#define __stringify_label(n) #n



#define __annotate_reachable(c) ({					\

	asm volatile(__stringify_label(c) ":\n\t"			\

		     ".pushsection .discard.reachable\n\t"		\

		     ".long %c0b - .\n\t"				\

		     ".popsection\n\t" : : "i" (__COUNTER__));		\

		     ".long " __stringify_label(c) "b - .\n\t"		\

		     ".popsection\n\t");				\

})

#define annotate_unreachable() ({					\

	asm volatile("%c0:\n\t"						\

#define annotate_reachable() __annotate_reachable(__COUNTER__)



#define __annotate_unreachable(c) ({					\

	asm volatile(__stringify_label(c) ":\n\t"			\

		     ".pushsection .discard.unreachable\n\t"		\

		     ".long %c0b - .\n\t"				\

		     ".popsection\n\t" : : "i" (__COUNTER__));		\

		     ".long " __stringify_label(c) "b - .\n\t"		\

		     ".popsection\n\t");				\

})

#define annotate_unreachable() __annotate_unreachable(__COUNTER__)



#define ASM_UNREACHABLE							\

	"999:\n\t"							\

	".pushsection .discard.unreachable\n\t"				\