The following commit has been merged into the locking/core branch of tip:
Commit-ID: 566a9522381495d27b596ee3bdc9578ba02a895d
Gitweb: https://git.kernel.org/tip/566a9522381495d27b596ee3bdc9578ba02a895d
Author: Jason Gerecke <killertofu@xxxxxxxxx>
AuthorDate: Thu, 11 Feb 2021 13:48:48 -08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 02 Mar 2021 15:06:34 +01:00
x86/jump_label: Mark arguments as const to satisfy asm constraints
When compiling an external kernel module with `-O0` or `-O1`, the following
compile error may be reported:
./arch/x86/include/asm/jump_label.h:25:2: error: impossible constraint in ‘asm’
25 | asm_volatile_goto("1:"
| ^~~~~~~~~~~~~~~~~
It appears that these lower optimization levels prevent GCC from detecting
that the key/branch arguments can be treated as constants and used as
immediate operands. To work around this, explicitly add the `const` label.
Signed-off-by: Jason Gerecke <jason.gerecke@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210211214848.536626-1-jason.gerecke@xxxxxxxxx
---
arch/x86/include/asm/jump_label.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 06c3cc2..7f20066 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -20,7 +20,7 @@
#include <linux/stringify.h>
#include <linux/types.h>
-static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
{
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
@@ -36,7 +36,7 @@ l_yes:
return true;
}
-static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
+static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{
asm_volatile_goto("1:"
".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
|