From: Jason Gerecke Date: Thu, 11 Feb 2021 21:48:48 +0000 (-0800) Subject: x86/jump_label: Mark arguments as const to satisfy asm constraints X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=864b435514b286c0be2a38a02f487aa28d990ef8;p=linux.git 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 Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Steven Rostedt (VMware) Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20210211214848.536626-1-jason.gerecke@wacom.com --- diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 06c3cc22a0586..7f2006645d840 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -20,7 +20,7 @@ #include #include -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"