arm64: use alternative auto-nop

Make use of the new alternative_if and alternative_else_nop_endif and
get rid of our homebew NOP sleds, making the code simpler to read.

Note that for cpu_do_switch_mm the ret has been moved out of the
alternative sequence, and in the default case there will be three
additional NOPs executed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 4 insertions, 9 deletions

diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index 4c1e700840b6..c3cd65e31814 100644
--- a/arch/arm64/lib/copy_page.S
+++ b/arch/arm64/lib/copy_page.S
@@ -29,14 +29,11 @@
  *      x1 - src
  */
 ENTRY(copy_page)
-alternative_if_not ARM64_HAS_NO_HW_PREFETCH
-        nop
-        nop
-alternative_else
+alternative_if ARM64_HAS_NO_HW_PREFETCH
         # Prefetch two cache lines ahead.
         prfm    pldl1strm, [x1, #128]
         prfm    pldl1strm, [x1, #256]
-alternative_endif
+alternative_else_nop_endif
 
         ldp     x2, x3, [x1]
         ldp     x4, x5, [x1, #16]
@@ -52,11 +49,9 @@ alternative_endif
 1:
         subs    x18, x18, #128
 
-alternative_if_not ARM64_HAS_NO_HW_PREFETCH
-        nop
-alternative_else
+alternative_if ARM64_HAS_NO_HW_PREFETCH
         prfm    pldl1strm, [x1, #384]
-alternative_endif
+alternative_else_nop_endif
 
         stnp    x2, x3, [x0]
         ldp     x2, x3, [x1]