linux/arch/sparc/kernel/spiterrs.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

241 lines
7.0 KiB
ArmAsm

/* We need to carefully read the error status, ACK the errors,
* prevent recursive traps, and pass the information on to C
* code for logging.
*
* We pass the AFAR in as-is, and we encode the status
* information as described in asm-sparc64/sfafsr.h
*/
.type __spitfire_access_error,#function
__spitfire_access_error:
/* Disable ESTATE error reporting so that we do not take
* recursive traps and RED state the processor.
*/
stxa %g0, [%g0] ASI_ESTATE_ERROR_EN
membar #Sync
mov UDBE_UE, %g1
ldxa [%g0] ASI_AFSR, %g4 ! Get AFSR
/* __spitfire_cee_trap branches here with AFSR in %g4 and
* UDBE_CE in %g1. It only clears ESTATE_ERR_CE in the ESTATE
* Error Enable register.
*/
__spitfire_cee_trap_continue:
ldxa [%g0] ASI_AFAR, %g5 ! Get AFAR
rdpr %tt, %g3
and %g3, 0x1ff, %g3 ! Paranoia
sllx %g3, SFSTAT_TRAP_TYPE_SHIFT, %g3
or %g4, %g3, %g4
rdpr %tl, %g3
cmp %g3, 1
mov 1, %g3
bleu %xcc, 1f
sllx %g3, SFSTAT_TL_GT_ONE_SHIFT, %g3
or %g4, %g3, %g4
/* Read in the UDB error register state, clearing the sticky
* error bits as-needed. We only clear them if the UE bit is
* set. Likewise, __spitfire_cee_trap below will only do so
* if the CE bit is set.
*
* NOTE: UltraSparc-I/II have high and low UDB error
* registers, corresponding to the two UDB units
* present on those chips. UltraSparc-IIi only
* has a single UDB, called "SDB" in the manual.
* For IIi the upper UDB register always reads
* as zero so for our purposes things will just
* work with the checks below.
*/
1: ldxa [%g0] ASI_UDBH_ERROR_R, %g3
and %g3, 0x3ff, %g7 ! Paranoia
sllx %g7, SFSTAT_UDBH_SHIFT, %g7
or %g4, %g7, %g4
andcc %g3, %g1, %g3 ! UDBE_UE or UDBE_CE
be,pn %xcc, 1f
nop
stxa %g3, [%g0] ASI_UDB_ERROR_W
membar #Sync
1: mov 0x18, %g3
ldxa [%g3] ASI_UDBL_ERROR_R, %g3
and %g3, 0x3ff, %g7 ! Paranoia
sllx %g7, SFSTAT_UDBL_SHIFT, %g7
or %g4, %g7, %g4
andcc %g3, %g1, %g3 ! UDBE_UE or UDBE_CE
be,pn %xcc, 1f
nop
mov 0x18, %g7
stxa %g3, [%g7] ASI_UDB_ERROR_W
membar #Sync
1: /* Ok, now that we've latched the error state, clear the
* sticky bits in the AFSR.
*/
stxa %g4, [%g0] ASI_AFSR
membar #Sync
rdpr %tl, %g2
cmp %g2, 1
rdpr %pil, %g2
bleu,pt %xcc, 1f
wrpr %g0, PIL_NORMAL_MAX, %pil
ba,pt %xcc, etraptl1
rd %pc, %g7
ba,a,pt %xcc, 2f
nop
1: ba,pt %xcc, etrap_irq
rd %pc, %g7
2:
#ifdef CONFIG_TRACE_IRQFLAGS
call trace_hardirqs_off
nop
#endif
mov %l4, %o1
mov %l5, %o2
call spitfire_access_error
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __spitfire_access_error,.-__spitfire_access_error
/* This is the trap handler entry point for ECC correctable
* errors. They are corrected, but we listen for the trap so
* that the event can be logged.
*
* Disrupting errors are either:
* 1) single-bit ECC errors during UDB reads to system
* memory
* 2) data parity errors during write-back events
*
* As far as I can make out from the manual, the CEE trap is
* only for correctable errors during memory read accesses by
* the front-end of the processor.
*
* The code below is only for trap level 1 CEE events, as it
* is the only situation where we can safely record and log.
* For trap level >1 we just clear the CE bit in the AFSR and
* return.
*
* This is just like __spiftire_access_error above, but it
* specifically handles correctable errors. If an
* uncorrectable error is indicated in the AFSR we will branch
* directly above to __spitfire_access_error to handle it
* instead. Uncorrectable therefore takes priority over
* correctable, and the error logging C code will notice this
* case by inspecting the trap type.
*/
.type __spitfire_cee_trap,#function
__spitfire_cee_trap:
ldxa [%g0] ASI_AFSR, %g4 ! Get AFSR
mov 1, %g3
sllx %g3, SFAFSR_UE_SHIFT, %g3
andcc %g4, %g3, %g0 ! Check for UE
bne,pn %xcc, __spitfire_access_error
nop
/* Ok, in this case we only have a correctable error.
* Indicate we only wish to capture that state in register
* %g1, and we only disable CE error reporting unlike UE
* handling which disables all errors.
*/
ldxa [%g0] ASI_ESTATE_ERROR_EN, %g3
andn %g3, ESTATE_ERR_CE, %g3
stxa %g3, [%g0] ASI_ESTATE_ERROR_EN
membar #Sync
/* Preserve AFSR in %g4, indicate UDB state to capture in %g1 */
ba,pt %xcc, __spitfire_cee_trap_continue
mov UDBE_CE, %g1
.size __spitfire_cee_trap,.-__spitfire_cee_trap
.type __spitfire_data_access_exception_tl1,#function
__spitfire_data_access_exception_tl1:
rdpr %pstate, %g4
wrpr %g4, PSTATE_MG|PSTATE_AG, %pstate
mov TLB_SFSR, %g3
mov DMMU_SFAR, %g5
ldxa [%g3] ASI_DMMU, %g4 ! Get SFSR
ldxa [%g5] ASI_DMMU, %g5 ! Get SFAR
stxa %g0, [%g3] ASI_DMMU ! Clear SFSR.FaultValid bit
membar #Sync
rdpr %tt, %g3
cmp %g3, 0x80 ! first win spill/fill trap
blu,pn %xcc, 1f
cmp %g3, 0xff ! last win spill/fill trap
bgu,pn %xcc, 1f
nop
ba,pt %xcc, winfix_dax
rdpr %tpc, %g3
1: sethi %hi(109f), %g7
ba,pt %xcc, etraptl1
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call spitfire_data_access_exception_tl1
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __spitfire_data_access_exception_tl1,.-__spitfire_data_access_exception_tl1
.type __spitfire_data_access_exception,#function
__spitfire_data_access_exception:
rdpr %pstate, %g4
wrpr %g4, PSTATE_MG|PSTATE_AG, %pstate
mov TLB_SFSR, %g3
mov DMMU_SFAR, %g5
ldxa [%g3] ASI_DMMU, %g4 ! Get SFSR
ldxa [%g5] ASI_DMMU, %g5 ! Get SFAR
stxa %g0, [%g3] ASI_DMMU ! Clear SFSR.FaultValid bit
membar #Sync
sethi %hi(109f), %g7
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call spitfire_data_access_exception
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __spitfire_data_access_exception,.-__spitfire_data_access_exception
.type __spitfire_insn_access_exception_tl1,#function
__spitfire_insn_access_exception_tl1:
rdpr %pstate, %g4
wrpr %g4, PSTATE_MG|PSTATE_AG, %pstate
mov TLB_SFSR, %g3
ldxa [%g3] ASI_IMMU, %g4 ! Get SFSR
rdpr %tpc, %g5 ! IMMU has no SFAR, use TPC
stxa %g0, [%g3] ASI_IMMU ! Clear FaultValid bit
membar #Sync
sethi %hi(109f), %g7
ba,pt %xcc, etraptl1
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call spitfire_insn_access_exception_tl1
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __spitfire_insn_access_exception_tl1,.-__spitfire_insn_access_exception_tl1
.type __spitfire_insn_access_exception,#function
__spitfire_insn_access_exception:
rdpr %pstate, %g4
wrpr %g4, PSTATE_MG|PSTATE_AG, %pstate
mov TLB_SFSR, %g3
ldxa [%g3] ASI_IMMU, %g4 ! Get SFSR
rdpr %tpc, %g5 ! IMMU has no SFAR, use TPC
stxa %g0, [%g3] ASI_IMMU ! Clear FaultValid bit
membar #Sync
sethi %hi(109f), %g7
ba,pt %xcc, etrap
109: or %g7, %lo(109b), %g7
mov %l4, %o1
mov %l5, %o2
call spitfire_insn_access_exception
add %sp, PTREGS_OFF, %o0
ba,a,pt %xcc, rtrap
.size __spitfire_insn_access_exception,.-__spitfire_insn_access_exception