As we're about to need to atomically manipulate some thread flags from entry.S, let's introduce two atomic primitives (test_and_clear_flag and set_flag) for that purpose. We provide two implementations: one using the traditional LL/SC instructions, and one using the ARMv8.1 atomics. Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> --- arch/arm64/include/asm/assembler.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 0bcc98dbba56..d3612ad8035e 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -26,6 +26,7 @@ #include <asm/asm-offsets.h> #include <asm/cpufeature.h> #include <asm/debug-monitors.h> +#include <asm/lse.h> #include <asm/page.h> #include <asm/pgtable-hwdef.h> #include <asm/ptrace.h> @@ -701,4 +702,40 @@ USER(\label, ic ivau, \tmp2) // invalidate I line PoU .Lyield_out_\@ : .endm +/* + * test_and_clear_flag: + * + * res: register containing the result (0 or 1 << bitnum) + * addr: address of the word to be manipulated + * bitnum: number of the bit in that word + * wtmp: temporary register, must be a 32bit reg + */ + .macro test_and_clear_flag, res, addr, bitnum, wtmp +alt_lse " prfm pstl1strm, [\addr]", "nop" +alt_lse "8:ldxr \res, [\addr]", "ldr \res, [\addr]" + tbz \res, #\bitnum, 9f +alt_lse " bic \res, \res, #(1 << \bitnum)", "mov \res, #(1 << \bitnum)" +alt_lse " stlxr \wtmp, \res, [\addr]", "ldclral \res, \res, [\addr]" +alt_lse " cbnz \wtmp, 8b", "nop" +alt_lse " dmb ish", "nop" +alt_lse " orr \res, \res, #(1 << \bitnum)", "nop" +9: + .endm + +/* + * set_flag: + * + * addr: address of the word to be manipulated + * bitnum: number of the bit in that word + * tmp: temporary register + * wtmp: temporary register, must be a 32bit reg + */ + .macro set_flag, addr, bitnum, tmp, wtmp +alt_lse " prfm pstl1strm, [\addr]", "mov \tmp, #(1 << \bitnum)" +alt_lse "8:ldxr \tmp, [\addr]", "stset \tmp, [\addr]" +alt_lse " orr \tmp, \tmp, #(1 << \bitnum)", "nop" +alt_lse " stxr \wtmp, \tmp, [\addr]", "nop" +alt_lse " cbnz \wtmp, 8b", "nop" + .endm + #endif /* __ASM_ASSEMBLER_H */ -- 2.14.2 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
