Marc Zyngier 9fd339a45b arm64: Work around broken GCC 4.9 handling of "S" constraint ... GCC 4.9 seems to have a problem with the "S" asm constraint when the symbol lives in the same compilation unit, and pretends the constraint is impossible: $ cat x.c void *foo(void) { static int x; int *addr; asm("adrp %0, %1" : "=r" (addr) : "S" (&x)); return addr; } $ ~/Work/gcc-linaro-aarch64-linux-gnu-4.9-2014.09_linux/bin/aarch64-linux-gnu-gcc -S -x c -O2 x.c x.c: In function ‘foo’: x.c:5:2: error: impossible constraint in ‘asm’ asm("adrp %0, %1" : "=r" (addr) : "S" (&x)); ^ Boo. Following revisions of the compiler work just fine, though. We can fallback to the "i" constraint for GCC version prior to 5.0, which *seems* to do the right thing. Hopefully we will be able to remove this at some point, but in the meantime this gets us going. Signed-off-by: Marc Zyngier <maz@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20201217111135.1536658-1-maz@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>		2020-12-17 11:46:20 +00:00
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asm	arm64: Work around broken GCC 4.9 handling of "S" constraint	2020-12-17 11:46:20 +00:00
uapi/asm	ARM:	2020-10-23 11:17:56 -07:00