arm64: assembler: introduce ldr_this_cpu
Shortly we will want to load a percpu variable in the return from
userspace path. We can save an instruction by folding the addition of
the percpu offset into the load instruction, and this patch adds a new
helper to do so.
At the same time, we clean up this_cpu_ptr for consistency. As with
{adr,ldr,str}_l, we change the template to take the destination register
first, and name this dst. Secondly, we rename the macro to adr_this_cpu,
following the scheme of adr_l, and matching the newly added
ldr_this_cpu.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 28bfe61..128a9ca 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -202,14 +202,25 @@ lr .req x30 // link register
.endm
/*
+ * @dst: Result of per_cpu(sym, smp_processor_id())
* @sym: The name of the per-cpu variable
- * @reg: Result of per_cpu(sym, smp_processor_id())
* @tmp: scratch register
*/
- .macro this_cpu_ptr, sym, reg, tmp
- adr_l \reg, \sym
+ .macro adr_this_cpu, dst, sym, tmp
+ adr_l \dst, \sym
mrs \tmp, tpidr_el1
- add \reg, \reg, \tmp
+ add \dst, \dst, \tmp
+ .endm
+
+ /*
+ * @dst: Result of READ_ONCE(per_cpu(sym, smp_processor_id()))
+ * @sym: The name of the per-cpu variable
+ * @tmp: scratch register
+ */
+ .macro ldr_this_cpu dst, sym, tmp
+ adr_l \dst, \sym
+ mrs \tmp, tpidr_el1
+ ldr \dst, [\dst, \tmp]
.endm
/*