compiler.h: Fix annotation macro misplacement with Clang

When building with Clang and CONFIG_TRACE_BRANCH_PROFILING, there are a
lot of unreachable warnings, like:

  arch/x86/kernel/traps.o: warning: objtool: handle_xfd_event()+0x134: unreachable instruction

Without an input to the inline asm, 'volatile' is ignored for some
reason and Clang feels free to move the reachable() annotation away from
its intended location.

Fix that by re-adding the counter value to the inputs.

Fixes: f1069a8756b9 ("compiler.h: Avoid using inline asm operand modifiers")
Fixes: c199f64ff93c ("instrumentation.h: Avoid using inline asm operand modifiers")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Link: https://lore.kernel.org/r/0417e96909b97a406323409210de7bf13df0b170.1636410380.git.jpoimboe@redhat.com
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Cc: Vasily Gorbik <[email protected]>
Cc: Miroslav Benes <[email protected]>

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 3d5af56337bdb5ea0c88dca48a45e7524bf86420..429dcebe2b9922a3153bc77d257d03b544926c80 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -121,7 +121,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
        asm volatile(__stringify_label(c) ":\n\t"                       \
                     ".pushsection .discard.reachable\n\t"              \
                     ".long " __stringify_label(c) "b - .\n\t"          \
-                    ".popsection\n\t");                                \
+                    ".popsection\n\t" : : "i" (c));                    \
 })
 #define annotate_reachable() __annotate_reachable(__COUNTER__)
 
@@ -129,7 +129,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
        asm volatile(__stringify_label(c) ":\n\t"                       \
                     ".pushsection .discard.unreachable\n\t"            \
                     ".long " __stringify_label(c) "b - .\n\t"          \
-                    ".popsection\n\t");                                \
+                    ".popsection\n\t" : : "i" (c));                    \
 })
 #define annotate_unreachable() __annotate_unreachable(__COUNTER__)
 

diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index fa2cd8c63dcc985cd6755b52700175346e70f346..24359b4a960537805898618a28e99b6ee1db44a5 100644 (file)
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -11,7 +11,7 @@
        asm volatile(__stringify(c) ": nop\n\t"                         \
                     ".pushsection .discard.instr_begin\n\t"            \
                     ".long " __stringify(c) "b - .\n\t"                \
-                    ".popsection\n\t");                                \
+                    ".popsection\n\t" : : "i" (c));                    \
 })
 #define instrumentation_begin() __instrumentation_begin(__COUNTER__)
 
@@ -50,7 +50,7 @@
        asm volatile(__stringify(c) ": nop\n\t"                         \
                     ".pushsection .discard.instr_end\n\t"              \
                     ".long " __stringify(c) "b - .\n\t"                \
-                    ".popsection\n\t");                                \
+                    ".popsection\n\t" : : "i" (c));                    \
 })
 #define instrumentation_end() __instrumentation_end(__COUNTER__)
 #else