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: 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

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index df5b405..7704790 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -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"                         \