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compiler.h: Avoid using inline asm operand modifiers

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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: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Josh 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
This commit is contained in:
Vasily Gorbik 2021-05-19 15:03:08 +02:00 committed by Josh Poimboeuf
parent 8852c55240
commit f1069a8756
1 changed files with 14 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

22
include/linux/compiler.h
View file

@ -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" \