linux/arch/sparc/kernel/misctrap.S
Babu Moger 0ae2d26ffe 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>
2017-03-27 21:51:40 -07:00

95 lines
2.0 KiB
ArmAsm

#ifdef CONFIG_KGDB
.globl arch_kgdb_breakpoint
.type arch_kgdb_breakpoint,#function
arch_kgdb_breakpoint:
ta 0x72
retl
nop
.size arch_kgdb_breakpoint,.-arch_kgdb_breakpoint
#endif
.type __do_privact,#function
__do_privact:
mov TLB_SFSR, %g3
stxa %g0, [%g3] ASI_DMMU ! Clear FaultValid bit
membar #Sync
sethi %hi(109f), %g7
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
call do_privact
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __do_privact,.-__do_privact
.type do_mna,#function
do_mna:
rdpr %tl, %g3
cmp %g3, 1
/* Setup %g4/%g5 now as they are used in the
* winfixup code.
*/
mov TLB_SFSR, %g3
mov DMMU_SFAR, %g4
ldxa [%g4] ASI_DMMU, %g4
ldxa [%g3] ASI_DMMU, %g5
stxa %g0, [%g3] ASI_DMMU ! Clear FaultValid bit
membar #Sync
bgu,pn %icc, winfix_mna
rdpr %tpc, %g3
1: sethi %hi(109f), %g7
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call mem_address_unaligned
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size do_mna,.-do_mna
.type do_lddfmna,#function
do_lddfmna:
sethi %hi(109f), %g7
mov TLB_SFSR, %g4
ldxa [%g4] ASI_DMMU, %g5
stxa %g0, [%g4] ASI_DMMU ! Clear FaultValid bit
membar #Sync
mov DMMU_SFAR, %g4
ldxa [%g4] ASI_DMMU, %g4
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call handle_lddfmna
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size do_lddfmna,.-do_lddfmna
.type do_stdfmna,#function
do_stdfmna:
sethi %hi(109f), %g7
mov TLB_SFSR, %g4
ldxa [%g4] ASI_DMMU, %g5
stxa %g0, [%g4] ASI_DMMU ! Clear FaultValid bit
membar #Sync
mov DMMU_SFAR, %g4
ldxa [%g4] ASI_DMMU, %g4
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call handle_stdfmna
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
nop
.size do_stdfmna,.-do_stdfmna
.type breakpoint_trap,#function
breakpoint_trap:
call sparc_breakpoint
add %sp, PTREGS_OFF, %o0
ba,pt %xcc, rtrap
nop
.size breakpoint_trap,.-breakpoint_trap