Messages in this thread | | | Date | Fri, 12 Feb 2021 10:14:39 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH] RFC: x86/jump_label: Mark arguments as const to satisfy asm constraints |
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On Thu, Feb 11, 2021 at 01:48:48PM -0800, Jason Gerecke wrote: > 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@wacom.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Ard Biesheuvel <ardb@kernel.org> > --- > Marked RFC since I'm not familiar with this subsystem or the asm blocks that > are impacted. Extra-close inspection would be appreciated.
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
-- Josh
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