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>

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 6880dcc..223d54a 100644 (file)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -150,13 +150,7 @@
        ldr     x23, [sp, #S_SP]                // load return stack pointer
        msr     sp_el0, x23
 #ifdef CONFIG_ARM64_ERRATUM_845719
-alternative_if_not ARM64_WORKAROUND_845719
-       nop
-       nop
-#ifdef CONFIG_PID_IN_CONTEXTIDR
-       nop
-#endif
-alternative_else
+alternative_if ARM64_WORKAROUND_845719
        tbz     x22, #4, 1f
 #ifdef CONFIG_PID_IN_CONTEXTIDR
        mrs     x29, contextidr_el1
@@ -165,7 +159,7 @@ alternative_else
        msr contextidr_el1, xzr
 #endif
 1:
-alternative_endif
+alternative_else_nop_endif
 #endif
        .endif
        msr     elr_el1, x21                    // set up the return data

diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index 4c1e700..c3cd65e 100644 (file)
--- 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]

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 5eb3596..1b11dcd 100644 (file)
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -127,17 +127,12 @@ ENTRY(cpu_do_switch_mm)
        bfi     x0, x1, #48, #16                // set the ASID
        msr     ttbr0_el1, x0                   // set TTBR0
        isb
-alternative_if_not ARM64_WORKAROUND_CAVIUM_27456
-       ret
-       nop
-       nop
-       nop
-alternative_else
+alternative_if ARM64_WORKAROUND_CAVIUM_27456
        ic      iallu
        dsb     nsh
        isb
+alternative_else_nop_endif
        ret
-alternative_endif
 ENDPROC(cpu_do_switch_mm)
 
        .pushsection ".idmap.text", "ax"