arch/sparc: Avoid DCTI Couples

Avoid un-intended DCTI Couples. Use of DCTI couples is deprecated.
Also address the "Programming Note" for optimal performance.

Here is the complete text from Oracle SPARC Architecture Specs.

6.3.4.7 DCTI Couples
"A delayed control transfer instruction (DCTI) in the delay slot of
another DCTI is referred to as a “DCTI couple”. The use of DCTI couples
is deprecated in the Oracle SPARC Architecture; no new software should
place a DCTI in the delay slot of another DCTI, because on future Oracle
SPARC Architecture implementations DCTI couples may execute either
slowly or differently than the programmer assumes it will.

SPARC V8 and SPARC V9 Compatibility Note
The SPARC V8 architecture left behavior undefined for a DCTI couple. The
SPARC V9 architecture defined behavior in that case, but as of
UltraSPARC Architecture 2005, use of DCTI couples was deprecated.
Software should not expect high performance from DCTI couples, and
performance of DCTI couples should be expected to decline further in
future processors.

Programming Note
As noted in TABLE 6-5 on page 115, an annulled branch-always
(branch-always with a = 1) instruction is not architecturally a DCTI.
However, since not all implementations make that distinction, for
optimal performance, a DCTI should not be placed in the instruction word
immediately following an annulled branch-always instruction (BA,A or
BPA,A)."

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index 6aa3da152c20008a08e752c4f9708ff6a89e3d72..44101196d02b5dacb5e3c67248b3c3de77c4a9b4 100644 (file)
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -96,6 +96,7 @@ sparc64_boot:
        andn    %g1, PSTATE_AM, %g1
        wrpr    %g1, 0x0, %pstate
        ba,a,pt %xcc, 1f
+        nop
 
        .globl  prom_finddev_name, prom_chosen_path, prom_root_node
        .globl  prom_getprop_name, prom_mmu_name, prom_peer_name
@@ -613,6 +614,7 @@ niagara_tlb_fixup:
         nop
 
        ba,a,pt %xcc, 80f
+        nop
 niagara4_patch:
        call    niagara4_patch_copyops
         nop
@@ -622,6 +624,7 @@ niagara4_patch:
         nop
 
        ba,a,pt %xcc, 80f
+        nop
 
 niagara2_patch:
        call    niagara2_patch_copyops
@@ -632,6 +635,7 @@ niagara2_patch:
         nop
 
        ba,a,pt %xcc, 80f
+        nop
 
 niagara_patch:
        call    niagara_patch_copyops

diff --git a/arch/sparc/kernel/misctrap.S b/arch/sparc/kernel/misctrap.S
index 34b4933900bf7665b30e791565795d5782351b60..9276d2f0dd8684edffa5a2a4f2f72ac4488a8c99 100644 (file)
--- a/arch/sparc/kernel/misctrap.S
+++ b/arch/sparc/kernel/misctrap.S
@@ -82,6 +82,7 @@ do_stdfmna:
        call            handle_stdfmna
         add            %sp, PTREGS_OFF, %o0
        ba,a,pt         %xcc, rtrap
+        nop
        .size           do_stdfmna,.-do_stdfmna
 
        .type           breakpoint_trap,#function

diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S
index 216948ca43829d0c0a5be837ff183f86d03dfb49..709a82ebd294c07bd4b87698c695325e5093a7e4 100644 (file)
--- a/arch/sparc/kernel/rtrap_64.S
+++ b/arch/sparc/kernel/rtrap_64.S
@@ -237,6 +237,7 @@ rt_continue:        ldx                     [%sp + PTREGS_OFF + PT_V9_G1], %g1
                bne,pt                  %xcc, user_rtt_fill_32bit
                 wrpr                   %g1, %cwp
                ba,a,pt                 %xcc, user_rtt_fill_64bit
+                nop
 
 user_rtt_fill_fixup_dax:
                ba,pt   %xcc, user_rtt_fill_fixup_common

diff --git a/arch/sparc/kernel/spiterrs.S b/arch/sparc/kernel/spiterrs.S
index 4a73009f66a5727e43ad45dbe1a2f7bded8cd48f..d7e5408428098d1138b0c132baa2d43dff3196a4 100644 (file)
--- a/arch/sparc/kernel/spiterrs.S
+++ b/arch/sparc/kernel/spiterrs.S
@@ -86,6 +86,7 @@ __spitfire_cee_trap_continue:
         rd             %pc, %g7
 
        ba,a,pt         %xcc, 2f
+        nop
 
 1:     ba,pt           %xcc, etrap_irq
         rd             %pc, %g7

diff --git a/arch/sparc/kernel/sun4v_tlb_miss.S b/arch/sparc/kernel/sun4v_tlb_miss.S
index 6179e19bc9b98ea4542b59bb4953c1f9f2718330..c19f352f46c7e2d6c08f203e4e926982fd00423c 100644 (file)
--- a/arch/sparc/kernel/sun4v_tlb_miss.S
+++ b/arch/sparc/kernel/sun4v_tlb_miss.S
@@ -352,6 +352,7 @@ sun4v_mna:
        call    sun4v_do_mna
         add    %sp, PTREGS_OFF, %o0
        ba,a,pt %xcc, rtrap
+        nop
 
        /* Privileged Action.  */
 sun4v_privact:

diff --git a/arch/sparc/kernel/urtt_fill.S b/arch/sparc/kernel/urtt_fill.S
index 5604a2b051d46bb822873a31b9b1f88a85253562..364af3250646817e58ce37c96f6c12faf8b37dde 100644 (file)
--- a/arch/sparc/kernel/urtt_fill.S
+++ b/arch/sparc/kernel/urtt_fill.S
@@ -92,6 +92,7 @@ user_rtt_fill_fixup_common:
                call    sun4v_data_access_exception
                 nop
                ba,a,pt %xcc, rtrap
+                nop
 
 1:             call    spitfire_data_access_exception
                 nop

diff --git a/arch/sparc/kernel/winfixup.S b/arch/sparc/kernel/winfixup.S
index 855019a8590ea5d556b71c9ae9356f7dcb629588..1ee173cc3c3943e4883670fd56537c63d199257b 100644 (file)
--- a/arch/sparc/kernel/winfixup.S
+++ b/arch/sparc/kernel/winfixup.S
@@ -152,6 +152,8 @@ fill_fixup_dax:
        call    sun4v_data_access_exception
         nop
        ba,a,pt %xcc, rtrap
+        nop
 1:     call    spitfire_data_access_exception
         nop
        ba,a,pt %xcc, rtrap
+        nop

diff --git a/arch/sparc/lib/NG2memcpy.S b/arch/sparc/lib/NG2memcpy.S
index c629dbd121b6e4fe64494c62bcad656747f05ef2..64dcd6cdb606c819e48efe0e5d755edcc816dbea 100644 (file)
--- a/arch/sparc/lib/NG2memcpy.S
+++ b/arch/sparc/lib/NG2memcpy.S
@@ -326,11 +326,13 @@ FUNC_NAME:        /* %o0=dst, %o1=src, %o2=len */
        blu             170f
         nop
        ba,a,pt         %xcc, 180f
+        nop
 
 4:     /* 32 <= low bits < 48 */
        blu             150f
         nop
        ba,a,pt         %xcc, 160f
+        nop
 5:     /* 0 < low bits < 32 */
        blu,a           6f
         cmp            %g2, 8
@@ -338,6 +340,7 @@ FUNC_NAME:  /* %o0=dst, %o1=src, %o2=len */
        blu             130f
         nop
        ba,a,pt         %xcc, 140f
+        nop
 6:     /* 0 < low bits < 16 */
        bgeu            120f
         nop
@@ -475,6 +478,7 @@ FUNC_NAME:  /* %o0=dst, %o1=src, %o2=len */
        brz,pt          %o2, 85f
         sub            %o0, %o1, GLOBAL_SPARE
        ba,a,pt         %XCC, 90f
+        nop
 
        .align          64
 75: /* 16 < len <= 64 */

diff --git a/arch/sparc/lib/NG4memcpy.S b/arch/sparc/lib/NG4memcpy.S
index 75bb93b1437f7f6f29ab17c96bc0b4c322f2a373..78ea962edcbee4c974481520de516e751d78a61d 100644 (file)
--- a/arch/sparc/lib/NG4memcpy.S
+++ b/arch/sparc/lib/NG4memcpy.S
@@ -530,4 +530,5 @@ FUNC_NAME:  /* %o0=dst, %o1=src, %o2=len */
        bne,pt          %icc, 1b
         EX_ST(STORE(stb, %g1, %o0 - 0x01), NG4_retl_o2_plus_1)
        ba,a,pt         %icc, .Lexit
+        nop
        .size           FUNC_NAME, .-FUNC_NAME

diff --git a/arch/sparc/lib/NG4memset.S b/arch/sparc/lib/NG4memset.S
index 41da4bdd95cbff451889992b06c8dd6893dfed30..7c0c81f18837e11902f8b473b7b480bfc13ab5a7 100644 (file)
--- a/arch/sparc/lib/NG4memset.S
+++ b/arch/sparc/lib/NG4memset.S
@@ -102,4 +102,5 @@ NG4bzero:
        bne,pt          %icc, 1b
         add            %o0, 0x30, %o0
        ba,a,pt         %icc, .Lpostloop
+        nop
        .size           NG4bzero,.-NG4bzero

diff --git a/arch/sparc/lib/NGmemcpy.S b/arch/sparc/lib/NGmemcpy.S
index d88c4ed50a0023cd8e2daa06689abc0d46d79f46..cd654a719b278b6c925a730a63195462d6e076df 100644 (file)
--- a/arch/sparc/lib/NGmemcpy.S
+++ b/arch/sparc/lib/NGmemcpy.S
@@ -394,6 +394,7 @@ FUNC_NAME:  /* %i0=dst, %i1=src, %i2=len */
        brz,pt          %i2, 85f
         sub            %o0, %i1, %i3
        ba,a,pt         %XCC, 90f
+        nop
 
        .align          64
 70: /* 16 < len <= 64 */