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powerpc/32: Only restore non volatile registers when required 

Until now, non volatile registers were restored everytime they
were saved, ie using EXC_XFER_STD meant saving and restoring
them while EXC_XFER_LITE meant neither saving not restoring them.

Now that they are always saved, EXC_XFER_STD means to restore
them and EXC_XFER_LITE means to not restore them.

Most of the users of EXC_XFER_STD only need to retrieve the
non volatile registers. For them there is no need to restore
the non volatile registers as they have not been modified.

Only very few exceptions require non volatile registers restore.

Opencode the few places which require saving of non volatile
registers.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d1cb12d8023cc6afc1f07150565571373c04945c.1615552867.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2021-03-12 12:50:40 +00:00 committed by Michael Ellerman
parent bce4c26a4e
commit 8f6ff5bd9b
6 changed files with 62 additions and 16 deletions
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1
arch/powerpc/kernel/entry_32.S
View File

@ -358,7 +358,6 @@ _ASM_NOKPROBE_SYMBOL(fast_exception_return)
.globl ret_from_except_full
ret_from_except_full:
REST_NVGPRS(r1)
/* fall through */
.globl ret_from_except

10
arch/powerpc/kernel/head_40x.S
View File

@ -228,12 +228,18 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
/* 0x0600 - Alignment Exception */
START_EXCEPTION(0x0600, Alignment)
EXCEPTION_PROLOG 0x600 Alignment handle_dar_dsisr=1
EXC_XFER_STD(0x600, alignment_exception)
prepare_transfer_to_handler
bl alignment_exception
REST_NVGPRS(r1)
b interrupt_return
/* 0x0700 - Program Exception */
START_EXCEPTION(0x0700, ProgramCheck)
EXCEPTION_PROLOG 0x700 ProgramCheck handle_dar_dsisr=1
EXC_XFER_STD(0x700, program_check_exception)
prepare_transfer_to_handler
bl program_check_exception
REST_NVGPRS(r1)
b interrupt_return
EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_STD)
EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_STD)

24
arch/powerpc/kernel/head_8xx.S
View File

@ -131,10 +131,18 @@ instruction_counter:
/* Alignment exception */
START_EXCEPTION(0x600, Alignment)
EXCEPTION_PROLOG 0x600 Alignment handle_dar_dsisr=1
EXC_XFER_STD(0x600, alignment_exception)
prepare_transfer_to_handler
bl alignment_exception
REST_NVGPRS(r1)
b interrupt_return
/* Program check exception */
EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
START_EXCEPTION(0x700, ProgramCheck)
EXCEPTION_PROLOG 0x700 ProgramCheck
prepare_transfer_to_handler
bl program_check_exception
REST_NVGPRS(r1)
b interrupt_return
/* Decrementer */
EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
@ -149,7 +157,12 @@ instruction_counter:
/* On the MPC8xx, this is a software emulation interrupt. It occurs
* for all unimplemented and illegal instructions.
*/
EXCEPTION(0x1000, SoftEmu, emulation_assist_interrupt, EXC_XFER_STD)
START_EXCEPTION(0x1000, SoftEmu)
EXCEPTION_PROLOG 0x1000 SoftEmu
prepare_transfer_to_handler
bl emulation_assist_interrupt
REST_NVGPRS(r1)
b interrupt_return
/*
* For the MPC8xx, this is a software tablewalk to load the instruction
@ -348,7 +361,10 @@ DARFixed:/* Return from dcbx instruction bug workaround */
EXCEPTION_PROLOG_2 0x1c00 DataBreakpoint handle_dar_dsisr=1
mfspr r4,SPRN_BAR
stw r4,_DAR(r11)
EXC_XFER_STD(0x1c00, do_break)
prepare_transfer_to_handler
bl do_break
REST_NVGPRS(r1)
b interrupt_return
#ifdef CONFIG_PERF_EVENTS
START_EXCEPTION(0x1d00, InstructionBreakpoint)

17
arch/powerpc/kernel/head_book3s_32.S
View File

@ -300,7 +300,10 @@ ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
andis. r0, r5, DSISR_DABRMATCH@h
bne- 1f
EXC_XFER_LITE(0x300, do_page_fault)
1: EXC_XFER_STD(0x300, do_break)
1: prepare_transfer_to_handler
bl do_break
REST_NVGPRS(r1)
b interrupt_return
/* Instruction access exception. */
@ -336,10 +339,18 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
/* Alignment exception */
START_EXCEPTION(0x600, Alignment)
EXCEPTION_PROLOG 0x600 Alignment handle_dar_dsisr=1
EXC_XFER_STD(0x600, alignment_exception)
prepare_transfer_to_handler
bl alignment_exception
REST_NVGPRS(r1)
b interrupt_return
/* Program check exception */
EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
START_EXCEPTION(0x700, ProgramCheck)
EXCEPTION_PROLOG 0x700 ProgramCheck
prepare_transfer_to_handler
bl program_check_exception
REST_NVGPRS(r1)
b interrupt_return
/* Floating-point unavailable */
START_EXCEPTION(0x800, FPUnavailable)

10
arch/powerpc/kernel/head_booke.h
View File

@ -483,14 +483,20 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
NORMAL_EXCEPTION_PROLOG(0x600, ALIGNMENT); \
mfspr r4,SPRN_DEAR; /* Grab the DEAR and save it */ \
stw r4,_DEAR(r11); \
EXC_XFER_STD(0x0600, alignment_exception)
prepare_transfer_to_handler; \
bl alignment_exception; \
REST_NVGPRS(r1); \
b interrupt_return
#define PROGRAM_EXCEPTION \
START_EXCEPTION(Program) \
NORMAL_EXCEPTION_PROLOG(0x700, PROGRAM); \
mfspr r4,SPRN_ESR; /* Grab the ESR and save it */ \
stw r4,_ESR(r11); \
EXC_XFER_STD(0x0700, program_check_exception)
prepare_transfer_to_handler; \
bl program_check_exception; \
REST_NVGPRS(r1); \
b interrupt_return
#define DECREMENTER_EXCEPTION \
START_EXCEPTION(Decrementer) \

16
arch/powerpc/kernel/head_fsl_booke.S
View File

@ -625,12 +625,20 @@ END_BTB_FLUSH_SECTION
/* SPE Floating Point Data */
#ifdef CONFIG_SPE
EXCEPTION(0x2030, SPE_FP_DATA, SPEFloatingPointData,
SPEFloatingPointException, EXC_XFER_STD)
START_EXCEPTION(SPEFloatingPointData)
NORMAL_EXCEPTION_PROLOG(0x2030, SPE_FP_DATA)
prepare_transfer_to_handler
bl SPEFloatingPointException
REST_NVGPRS(r1)
b interrupt_return
/* SPE Floating Point Round */
EXCEPTION(0x2050, SPE_FP_ROUND, SPEFloatingPointRound, \
SPEFloatingPointRoundException, EXC_XFER_STD)
START_EXCEPTION(SPEFloatingPointRound)
NORMAL_EXCEPTION_PROLOG(0x2050, SPE_FP_ROUND)
prepare_transfer_to_handler
bl SPEFloatingPointRoundException
REST_NVGPRS(r1)
b interrupt_return
#elif defined(CONFIG_SPE_POSSIBLE)
EXCEPTION(0x2040, SPE_FP_DATA, SPEFloatingPointData,
unknown_exception, EXC_XFER_STD)