* [RFC PATCH 0/9] powerpc/64s: fast interrupt exit
@ 2020-11-06 15:59 Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 1/9] powerpc/64s: syscall real mode entry use mtmsrd rather than rfid Nicholas Piggin
` (9 more replies)
0 siblings, 10 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
This series attempts to improve the speed of interrupts and system calls
in two major ways.
Firstly, the SRR/HSRR registers do not need to be reloaded if they were
not used or clobbered fur the duration of the interrupt.
Secondly, an alternate return location facility is added for soft-masked
asynchronous interrupts and then that's used to set everything up for
return without having to disable MSR RI or EE.
After this series, the entire system call / interrupt handler fast path
executes no mtsprs and one mtmsrd to enable interrupts initially, and
the system call vectored path doesn't even need to do that.
Thanks,
Nick
Nicholas Piggin (9):
powerpc/64s: syscall real mode entry use mtmsrd rather than rfid
powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]
powerpc/64s: introduce different functions to return from SRR vs HSRR
interrupts
powerpc/64s: avoid reloading (H)SRR registers if they are still valid
powerpc/64: move interrupt return asm to interrupt_64.S
powerpc/64s: save one more register in the masked interrupt handler
powerpc/64s: allow alternate return locations for soft-masked
interrupts
powerpc/64s: interrupt soft-enable race fix
powerpc/64s: use interrupt restart table to speed up return from
interrupt
arch/powerpc/Kconfig.debug | 5 +
arch/powerpc/include/asm/asm-prototypes.h | 4 +-
arch/powerpc/include/asm/head-64.h | 2 +-
arch/powerpc/include/asm/interrupt.h | 18 +
arch/powerpc/include/asm/paca.h | 3 +
arch/powerpc/include/asm/ppc_asm.h | 8 +
arch/powerpc/include/asm/ptrace.h | 28 +-
arch/powerpc/kernel/asm-offsets.c | 5 +
arch/powerpc/kernel/entry_64.S | 508 ---------------
arch/powerpc/kernel/exceptions-64s.S | 180 ++++--
arch/powerpc/kernel/fpu.S | 2 +
arch/powerpc/kernel/head_64.S | 5 +-
arch/powerpc/kernel/interrupt_64.S | 720 +++++++++++++++++++++
arch/powerpc/kernel/irq.c | 79 ++-
arch/powerpc/kernel/kgdb.c | 2 +-
arch/powerpc/kernel/kprobes-ftrace.c | 2 +-
arch/powerpc/kernel/kprobes.c | 10 +-
arch/powerpc/kernel/process.c | 21 +-
arch/powerpc/kernel/rtas.c | 13 +-
arch/powerpc/kernel/signal.c | 2 +-
arch/powerpc/kernel/signal_64.c | 14 +
arch/powerpc/kernel/syscall_64.c | 242 ++++---
arch/powerpc/kernel/syscalls.c | 2 +
arch/powerpc/kernel/traps.c | 18 +-
arch/powerpc/kernel/vector.S | 6 +-
arch/powerpc/kernel/vmlinux.lds.S | 10 +
arch/powerpc/lib/Makefile | 2 +-
arch/powerpc/lib/restart_table.c | 26 +
arch/powerpc/lib/sstep.c | 5 +-
arch/powerpc/math-emu/math.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/powerpc/perf/core-book3s.c | 19 +-
arch/powerpc/platforms/powernv/opal-call.c | 3 +
arch/powerpc/sysdev/fsl_pci.c | 2 +-
34 files changed, 1244 insertions(+), 726 deletions(-)
create mode 100644 arch/powerpc/kernel/interrupt_64.S
create mode 100644 arch/powerpc/lib/restart_table.c
--
2.23.0
^ permalink raw reply [flat|nested] 14+ messages in thread
* [RFC PATCH 1/9] powerpc/64s: syscall real mode entry use mtmsrd rather than rfid
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 2/9] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE] Nicholas Piggin
` (8 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
Have the real mode system call entry handler branch to the kernel
0xc000... address and then use mtmsrd to enable the MMU, rather than use
SRRs and rfid.
Commit 8729c26e675c ("powerpc/64s/exception: Move real to virt switch
into the common handler") implemented this style of real mode entry for
other interrupt handlers, so this brings system calls into line with
them, which is the main motivcation for the change.
This tends to be slightly faster due to avoiding the mtsprs, and it also
does not clobber the SRR registers, which becomes important in a
subsequent change. The real mode entry points don't tend to be too
important for performance these days, but it is possible for a
hypervisor to run guests in AIL=0 mode for certian reasons.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/entry_64.S | 6 ++++++
arch/powerpc/kernel/exceptions-64s.S | 9 +++------
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 479fb58844fa..bd8cc7a214d3 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -225,6 +225,12 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_emulate)
b system_call_vectored_common
#endif
+ .balign IFETCH_ALIGN_BYTES
+ .globl system_call_common_real
+system_call_common_real:
+ ld r10,PACAKMSR(r13) /* get MSR value for kernel */
+ mtmsrd r10
+
.balign IFETCH_ALIGN_BYTES
.globl system_call_common
system_call_common:
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 1db6b3438c88..ea7bb7cc0db1 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1901,12 +1901,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE)
HMT_MEDIUM
.if ! \virt
- __LOAD_HANDLER(r10, system_call_common)
- mtspr SPRN_SRR0,r10
- ld r10,PACAKMSR(r13)
- mtspr SPRN_SRR1,r10
- RFI_TO_KERNEL
- b . /* prevent speculative execution */
+ __LOAD_HANDLER(r10, system_call_common_real)
+ mtctr r10
+ bctr
.else
li r10,MSR_RI
mtmsrd r10,1 /* Set RI (EE=0) */
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 2/9] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 1/9] powerpc/64s: syscall real mode entry use mtmsrd rather than rfid Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 3/9] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts Nicholas Piggin
` (7 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
This extends the MSR[RI]=0 window a little further into the system
call in order to pair RI and EE enabling with a single mtmsrd.
XXX: May need to make this radix-only opt. - might take SLB or HPT faults
on the context tracking, etc.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index ea7bb7cc0db1..ad9f51e49806 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1905,8 +1905,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE)
mtctr r10
bctr
.else
- li r10,MSR_RI
- mtmsrd r10,1 /* Set RI (EE=0) */
#ifdef CONFIG_RELOCATABLE
__LOAD_HANDLER(r10, system_call_common)
mtctr r10
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 3/9] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 1/9] powerpc/64s: syscall real mode entry use mtmsrd rather than rfid Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 2/9] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE] Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 4/9] powerpc/64s: avoid reloading (H)SRR registers if they are still valid Nicholas Piggin
` (6 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
This makes no real difference yet except that HSRR type interrupts will
use hrfid to return. This is important for the next patch.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/entry_64.S | 58 +++++++++++++++------
arch/powerpc/kernel/exceptions-64s.S | 78 +++++++++++++++-------------
arch/powerpc/kernel/vector.S | 2 +-
3 files changed, 85 insertions(+), 53 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index bd8cc7a214d3..53027fc9cd31 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -648,47 +648,54 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
blr
#ifdef CONFIG_PPC_BOOK3S
+
/*
* If MSR EE/RI was never enabled, IRQs not reconciled, NVGPRs not
* touched, no exit work created, then this can be used.
*/
.balign IFETCH_ALIGN_BYTES
- .globl fast_interrupt_return
-fast_interrupt_return:
-_ASM_NOKPROBE_SYMBOL(fast_interrupt_return)
+ .globl fast_interrupt_return_srr
+fast_interrupt_return_srr:
+_ASM_NOKPROBE_SYMBOL(fast_interrupt_return_srr)
kuap_check_amr r3, r4
ld r5,_MSR(r1)
andi. r0,r5,MSR_PR
- bne .Lfast_user_interrupt_return
+ bne .Lfast_user_interrupt_return_srr
kuap_restore_amr r3, r4
andi. r0,r5,MSR_RI
li r3,0 /* 0 return value, no EMULATE_STACK_STORE */
- bne+ .Lfast_kernel_interrupt_return
+ bne+ .Lfast_kernel_interrupt_return_srr
addi r3,r1,STACK_FRAME_OVERHEAD
bl unrecoverable_exception
b . /* should not get here */
+.macro interrupt_return_macro srr
.balign IFETCH_ALIGN_BYTES
- .globl interrupt_return
-interrupt_return:
-_ASM_NOKPROBE_SYMBOL(interrupt_return)
+ .globl interrupt_return_\srr
+interrupt_return_\srr\():
+_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
ld r4,_MSR(r1)
andi. r0,r4,MSR_PR
- beq .Lkernel_interrupt_return
+ beq .Lkernel_interrupt_return_\srr
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_user_prepare
cmpdi r3,0
- bne- .Lrestore_nvgprs
+ bne- .Lrestore_nvgprs_\srr
-.Lfast_user_interrupt_return:
+.Lfast_user_interrupt_return_\srr:
ld r11,_NIP(r1)
ld r12,_MSR(r1)
BEGIN_FTR_SECTION
ld r10,_PPR(r1)
mtspr SPRN_PPR,r10
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+ .ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
+ .else
+ mtspr SPRN_HSRR0,r11
+ mtspr SPRN_HSRR1,r12
+ .endif
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
@@ -715,24 +722,33 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
REST_GPR(6, r1)
REST_GPR(0, r1)
REST_GPR(1, r1)
+ .ifc \srr,srr
RFI_TO_USER
+ .else
+ HRFI_TO_USER
+ .endif
b . /* prevent speculative execution */
-.Lrestore_nvgprs:
+.Lrestore_nvgprs_\srr\():
REST_NVGPRS(r1)
- b .Lfast_user_interrupt_return
+ b .Lfast_user_interrupt_return_\srr
.balign IFETCH_ALIGN_BYTES
-.Lkernel_interrupt_return:
+.Lkernel_interrupt_return_\srr\():
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_kernel_prepare
-.Lfast_kernel_interrupt_return:
+.Lfast_kernel_interrupt_return_\srr\():
cmpdi cr1,r3,0
ld r11,_NIP(r1)
ld r12,_MSR(r1)
+ .ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
+ .else
+ mtspr SPRN_HSRR0,r11
+ mtspr SPRN_HSRR1,r12
+ .endif
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
@@ -766,7 +782,11 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
REST_GPR(6, r1)
REST_GPR(0, r1)
REST_GPR(1, r1)
+ .ifc \srr,srr
RFI_TO_KERNEL
+ .else
+ HRFI_TO_KERNEL
+ .endif
b . /* prevent speculative execution */
1: /*
@@ -786,8 +806,16 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
std r9,0(r1) /* perform store component of stdu */
ld r9,PACA_EXGEN+0(r13)
+ .ifc \srr,srr
RFI_TO_KERNEL
+ .else
+ HRFI_TO_KERNEL
+ .endif
b . /* prevent speculative execution */
+.endm
+
+interrupt_return_macro srr
+interrupt_return_macro hsrr
#endif /* CONFIG_PPC_BOOK3S */
#ifdef CONFIG_PPC_RTAS
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index ad9f51e49806..1f725a3ac2f3 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1236,7 +1236,7 @@ EXC_COMMON_BEGIN(machine_check_common)
mtmsrd r10,1
addi r3,r1,STACK_FRAME_OVERHEAD
bl machine_check_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM machine_check
@@ -1360,10 +1360,10 @@ MMU_FTR_SECTION_ELSE
bl do_page_fault
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
cmpdi r3,0
- beq+ interrupt_return
+ beq+ interrupt_return_srr
/* We need to restore NVGPRS */
REST_NVGPRS(r1)
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM data_access
@@ -1410,7 +1410,7 @@ BEGIN_MMU_FTR_SECTION
bl do_slb_fault
cmpdi r3,0
bne- 1f
- b fast_interrupt_return
+ b fast_interrupt_return_srr
1: /* Error case */
MMU_FTR_SECTION_ELSE
/* Radix case, access is outside page table range */
@@ -1419,7 +1419,7 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
std r3,RESULT(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_bad_slb_fault
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM data_access_slb
@@ -1458,10 +1458,10 @@ MMU_FTR_SECTION_ELSE
bl do_page_fault
ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
cmpdi r3,0
- beq+ interrupt_return
+ beq+ interrupt_return_srr
/* We need to restore NVGPRS */
REST_NVGPRS(r1)
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM instruction_access
@@ -1499,7 +1499,7 @@ BEGIN_MMU_FTR_SECTION
bl do_slb_fault
cmpdi r3,0
bne- 1f
- b fast_interrupt_return
+ b fast_interrupt_return_srr
1: /* Error case */
MMU_FTR_SECTION_ELSE
/* Radix case, access is outside page table range */
@@ -1508,7 +1508,7 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
std r3,RESULT(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_bad_slb_fault
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM instruction_access_slb
@@ -1554,7 +1554,11 @@ EXC_COMMON_BEGIN(hardware_interrupt_common)
GEN_COMMON hardware_interrupt
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_IRQ
- b interrupt_return
+ BEGIN_FTR_SECTION
+ b interrupt_return_hsrr
+ FTR_SECTION_ELSE
+ b interrupt_return_srr
+ ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
GEN_KVM hardware_interrupt
@@ -1583,7 +1587,7 @@ EXC_COMMON_BEGIN(alignment_common)
addi r3,r1,STACK_FRAME_OVERHEAD
bl alignment_exception
REST_NVGPRS(r1) /* instruction emulation may change GPRs */
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM alignment
@@ -1647,7 +1651,7 @@ EXC_COMMON_BEGIN(program_check_common)
addi r3,r1,STACK_FRAME_OVERHEAD
bl program_check_exception
REST_NVGPRS(r1) /* instruction emulation may change GPRs */
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM program_check
@@ -1692,12 +1696,12 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_IFSET(CPU_FTR_TM)
#endif
bl load_up_fpu
- b fast_interrupt_return
+ b fast_interrupt_return_srr
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
2: /* User process was in a transaction */
addi r3,r1,STACK_FRAME_OVERHEAD
bl fp_unavailable_tm
- b interrupt_return
+ b interrupt_return_srr
#endif
GEN_KVM fp_unavailable
@@ -1738,7 +1742,7 @@ EXC_COMMON_BEGIN(decrementer_common)
GEN_COMMON decrementer
addi r3,r1,STACK_FRAME_OVERHEAD
bl timer_interrupt
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM decrementer
@@ -1826,7 +1830,7 @@ EXC_COMMON_BEGIN(doorbell_super_common)
#else
bl unknown_async_exception
#endif
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM doorbell_super
@@ -1995,7 +1999,7 @@ EXC_COMMON_BEGIN(single_step_common)
GEN_COMMON single_step
addi r3,r1,STACK_FRAME_OVERHEAD
bl single_step_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM single_step
@@ -2036,7 +2040,7 @@ BEGIN_MMU_FTR_SECTION
MMU_FTR_SECTION_ELSE
bl unknown_exception
ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_TYPE_RADIX)
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM h_data_storage
@@ -2063,7 +2067,7 @@ EXC_COMMON_BEGIN(h_instr_storage_common)
GEN_COMMON h_instr_storage
addi r3,r1,STACK_FRAME_OVERHEAD
bl unknown_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM h_instr_storage
@@ -2089,7 +2093,7 @@ EXC_COMMON_BEGIN(emulation_assist_common)
addi r3,r1,STACK_FRAME_OVERHEAD
bl emulation_assist_interrupt
REST_NVGPRS(r1) /* instruction emulation may change GPRs */
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM emulation_assist
@@ -2170,7 +2174,7 @@ EXC_COMMON_BEGIN(hmi_exception_common)
GEN_COMMON hmi_exception
addi r3,r1,STACK_FRAME_OVERHEAD
bl handle_hmi_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM hmi_exception
@@ -2202,7 +2206,7 @@ EXC_COMMON_BEGIN(h_doorbell_common)
#else
bl unknown_async_exception
#endif
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM h_doorbell
@@ -2230,7 +2234,7 @@ EXC_COMMON_BEGIN(h_virt_irq_common)
GEN_COMMON h_virt_irq
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_IRQ
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM h_virt_irq
@@ -2275,7 +2279,7 @@ EXC_COMMON_BEGIN(performance_monitor_common)
GEN_COMMON performance_monitor
addi r3,r1,STACK_FRAME_OVERHEAD
bl performance_monitor_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM performance_monitor
@@ -2314,19 +2318,19 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_NESTED(CPU_FTR_TM, CPU_FTR_TM, 69)
#endif
bl load_up_altivec
- b fast_interrupt_return
+ b fast_interrupt_return_srr
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
2: /* User process was in a transaction */
addi r3,r1,STACK_FRAME_OVERHEAD
bl altivec_unavailable_tm
- b interrupt_return
+ b interrupt_return_srr
#endif
1:
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif
addi r3,r1,STACK_FRAME_OVERHEAD
bl altivec_unavailable_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM altivec_unavailable
@@ -2369,14 +2373,14 @@ BEGIN_FTR_SECTION
2: /* User process was in a transaction */
addi r3,r1,STACK_FRAME_OVERHEAD
bl vsx_unavailable_tm
- b interrupt_return
+ b interrupt_return_srr
#endif
1:
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
addi r3,r1,STACK_FRAME_OVERHEAD
bl vsx_unavailable_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM vsx_unavailable
@@ -2406,7 +2410,7 @@ EXC_COMMON_BEGIN(facility_unavailable_common)
addi r3,r1,STACK_FRAME_OVERHEAD
bl facility_unavailable_exception
REST_NVGPRS(r1) /* instruction emulation may change GPRs */
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM facility_unavailable
@@ -2436,7 +2440,7 @@ EXC_COMMON_BEGIN(h_facility_unavailable_common)
addi r3,r1,STACK_FRAME_OVERHEAD
bl facility_unavailable_exception
REST_NVGPRS(r1) /* XXX Shouldn't be necessary in practice */
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM h_facility_unavailable
@@ -2469,7 +2473,7 @@ EXC_COMMON_BEGIN(cbe_system_error_common)
GEN_COMMON cbe_system_error
addi r3,r1,STACK_FRAME_OVERHEAD
bl cbe_system_error_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM cbe_system_error
@@ -2497,7 +2501,7 @@ EXC_COMMON_BEGIN(instruction_breakpoint_common)
GEN_COMMON instruction_breakpoint
addi r3,r1,STACK_FRAME_OVERHEAD
bl instruction_breakpoint_exception
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM instruction_breakpoint
@@ -2619,7 +2623,7 @@ EXC_COMMON_BEGIN(denorm_exception_common)
GEN_COMMON denorm_exception
addi r3,r1,STACK_FRAME_OVERHEAD
bl unknown_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM denorm_exception
@@ -2640,7 +2644,7 @@ EXC_COMMON_BEGIN(cbe_maintenance_common)
GEN_COMMON cbe_maintenance
addi r3,r1,STACK_FRAME_OVERHEAD
bl cbe_maintenance_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM cbe_maintenance
@@ -2672,7 +2676,7 @@ EXC_COMMON_BEGIN(altivec_assist_common)
#else
bl unknown_exception
#endif
- b interrupt_return
+ b interrupt_return_srr
GEN_KVM altivec_assist
@@ -2693,7 +2697,7 @@ EXC_COMMON_BEGIN(cbe_thermal_common)
GEN_COMMON cbe_thermal
addi r3,r1,STACK_FRAME_OVERHEAD
bl cbe_thermal_exception
- b interrupt_return
+ b interrupt_return_hsrr
GEN_KVM cbe_thermal
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 801dc28fdcca..2c948e7b0d00 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -133,7 +133,7 @@ _GLOBAL(load_up_vsx)
/* enable use of VSX after return */
oris r12,r12,MSR_VSX@h
std r12,_MSR(r1)
- b fast_interrupt_return
+ b fast_interrupt_return_srr
#endif /* CONFIG_VSX */
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 4/9] powerpc/64s: avoid reloading (H)SRR registers if they are still valid
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (2 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 3/9] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 5/9] powerpc/64: move interrupt return asm to interrupt_64.S Nicholas Piggin
` (5 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
When an interrupt is taken, the SRR registers are set to return to
where it left off. Unless they are modified in the meantime, or the
return address or MSR are modified, there is no need to reload these
registers when returning from interrupt.
Introduce per-CPU flags that track the validity of SRR and HSRR
registers, clear them when returning from interrupt, using the registers
for something else (e.g., OPAL calls), or adjusting return address or MSR.
This improves the performance of interrupt returns.
XXX: 64e build breaks
XXX: may not need to invalidate both hsrr and srr all the time
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/Kconfig.debug | 5 ++
arch/powerpc/include/asm/paca.h | 2 +
arch/powerpc/include/asm/ptrace.h | 15 +++++
arch/powerpc/kernel/asm-offsets.c | 2 +
arch/powerpc/kernel/entry_64.S | 75 +++++++++++++++++++---
arch/powerpc/kernel/exceptions-64s.S | 27 ++++++++
arch/powerpc/kernel/fpu.S | 2 +
arch/powerpc/kernel/kgdb.c | 2 +-
arch/powerpc/kernel/kprobes-ftrace.c | 2 +-
arch/powerpc/kernel/kprobes.c | 10 +--
arch/powerpc/kernel/process.c | 21 +++++-
arch/powerpc/kernel/rtas.c | 13 +++-
arch/powerpc/kernel/signal.c | 2 +-
arch/powerpc/kernel/signal_64.c | 14 ++++
arch/powerpc/kernel/syscalls.c | 2 +
arch/powerpc/kernel/traps.c | 18 +++---
arch/powerpc/kernel/vector.S | 4 ++
arch/powerpc/lib/sstep.c | 5 +-
arch/powerpc/math-emu/math.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/powerpc/platforms/powernv/opal-call.c | 3 +
arch/powerpc/sysdev/fsl_pci.c | 2 +-
22 files changed, 197 insertions(+), 33 deletions(-)
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index b88900f4832f..ad1f5bf6ab3d 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -84,6 +84,11 @@ config MSI_BITMAP_SELFTEST
config PPC_IRQ_SOFT_MASK_DEBUG
bool "Include extra checks for powerpc irq soft masking"
+ depends on PPC64
+
+config PPC_RFI_SRR_DEBUG
+ bool "Include extra checks for RFI SRR register validity"
+ depends on PPC_BOOK3S_64
config XMON
bool "Include xmon kernel debugger"
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 9454d29ff4b4..58e9995c3184 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -170,6 +170,8 @@ struct paca_struct {
#ifdef CONFIG_PPC_BOOK3E
u16 trap_save; /* Used when bad stack is encountered */
#endif
+ u8 hsrr_valid; /* HSRRs set for HRFID */
+ u8 srr_valid; /* SRRs set for RFID */
u8 irq_soft_mask; /* mask for irq soft masking */
u8 irq_happened; /* irq happened while soft-disabled */
u8 irq_work_pending; /* IRQ_WORK interrupt while soft-disable */
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index e2c778c176a3..2c3e773ce292 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -110,6 +110,7 @@ struct pt_regs
#endif /* __powerpc64__ */
#ifndef __ASSEMBLY__
+#include <asm/paca.h>
static inline unsigned long instruction_pointer(struct pt_regs *regs)
{
@@ -160,6 +161,20 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
regs->gpr[3] = rc;
}
+static inline void regs_set_return_ip(struct pt_regs *regs, unsigned long ip)
+{
+ regs->nip = ip;
+#ifdef CONFIG_PPC_BOOK3S
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+#endif
+}
+
+static inline void regs_add_return_ip(struct pt_regs *regs, long offset)
+{
+ regs_set_return_ip(regs, regs->nip + offset);
+}
+
#ifdef __powerpc64__
#define user_mode(regs) ((((regs)->msr) >> MSR_PR_LG) & 0x1)
#else
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index c2722ff36e98..ea13e35dd511 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -210,6 +210,8 @@ int main(void)
OFFSET(PACATOC, paca_struct, kernel_toc);
OFFSET(PACAKBASE, paca_struct, kernelbase);
OFFSET(PACAKMSR, paca_struct, kernel_msr);
+ OFFSET(PACAHSRR_VALID, paca_struct, hsrr_valid);
+ OFFSET(PACASRR_VALID, paca_struct, srr_valid);
OFFSET(PACAIRQSOFTMASK, paca_struct, irq_soft_mask);
OFFSET(PACAIRQHAPPENED, paca_struct, irq_happened);
OFFSET(PACA_FTRACE_ENABLED, paca_struct, ftrace_enabled);
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 53027fc9cd31..6236a88a592f 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -65,6 +65,30 @@ exception_marker:
.align 7
#ifdef CONFIG_PPC_BOOK3S
+.macro DEBUG_SRR_VALID srr
+#ifdef CONFIG_PPC_RFI_SRR_DEBUG
+ .ifc \srr,srr
+ mfspr r11,SPRN_SRR0
+ ld r12,_NIP(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ mfspr r11,SPRN_SRR1
+ ld r12,_MSR(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ .else
+ mfspr r11,SPRN_HSRR0
+ ld r12,_NIP(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ mfspr r11,SPRN_HSRR1
+ ld r12,_MSR(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ .endif
+#endif
+.endm
+
.macro system_call_vectored name trapnr
.globl system_call_vectored_\name
system_call_vectored_\name:
@@ -289,6 +313,9 @@ END_BTB_FLUSH_SECTION
ld r11,exception_marker@toc(r2)
std r11,-16(r10) /* "regshere" marker */
+ li r11,1
+ stb r11,PACASRR_VALID(r13)
+
/*
* RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
* would clobber syscall parameters. Also we always enter with IRQs
@@ -310,18 +337,25 @@ END_BTB_FLUSH_SECTION
bl syscall_exit_prepare
ld r2,_CCR(r1)
+ ld r6,_LINK(r1)
+ mtlr r6
+
+ lbz r4,PACASRR_VALID(r13)
+ cmpdi r4,0
+ bne 1f
+ li r4,0
+ stb r4,PACASRR_VALID(r13)
ld r4,_NIP(r1)
ld r5,_MSR(r1)
- ld r6,_LINK(r1)
+ mtspr SPRN_SRR0,r4
+ mtspr SPRN_SRR1,r5
+1:
+ DEBUG_SRR_VALID srr
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
- mtspr SPRN_SRR0,r4
- mtspr SPRN_SRR1,r5
- mtlr r6
-
cmpdi r3,0
bne .Lsyscall_restore_regs
/* Zero volatile regs that may contain sensitive kernel data */
@@ -648,7 +682,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
blr
#ifdef CONFIG_PPC_BOOK3S
-
/*
* If MSR EE/RI was never enabled, IRQs not reconciled, NVGPRs not
* touched, no exit work created, then this can be used.
@@ -683,19 +716,32 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
bne- .Lrestore_nvgprs_\srr
.Lfast_user_interrupt_return_\srr:
- ld r11,_NIP(r1)
- ld r12,_MSR(r1)
BEGIN_FTR_SECTION
ld r10,_PPR(r1)
mtspr SPRN_PPR,r10
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+ .ifc \srr,srr
+ lbz r4,PACASRR_VALID(r13)
+ .else
+ lbz r4,PACAHSRR_VALID(r13)
+ .endif
+ cmpdi r4,0
+ li r4,0
+ bne 1f
+ ld r11,_NIP(r1)
+ ld r12,_MSR(r1)
.ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
+1:
+ stb r4,PACASRR_VALID(r13)
.else
mtspr SPRN_HSRR0,r11
mtspr SPRN_HSRR1,r12
+1:
+ stb r4,PACAHSRR_VALID(r13)
.endif
+ DEBUG_SRR_VALID \srr
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
@@ -740,15 +786,28 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
.Lfast_kernel_interrupt_return_\srr\():
cmpdi cr1,r3,0
+ .ifc \srr,srr
+ lbz r4,PACASRR_VALID(r13)
+ .else
+ lbz r4,PACAHSRR_VALID(r13)
+ .endif
+ cmpdi r4,0
+ li r4,0
+ bne 1f
ld r11,_NIP(r1)
ld r12,_MSR(r1)
.ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
+1:
+ stb r4,PACASRR_VALID(r13)
.else
mtspr SPRN_HSRR0,r11
mtspr SPRN_HSRR1,r12
+1:
+ stb r4,PACAHSRR_VALID(r13)
.endif
+ DEBUG_SRR_VALID \srr
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 1f725a3ac2f3..b370a5f334fc 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -567,6 +567,20 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real)
std r0,GPR0(r1) /* save r0 in stackframe */
std r10,GPR1(r1) /* save r1 in stackframe */
+ /* Mark our [H]SRRs valid for return */
+ li r10,1
+ .if IHSRR_IF_HVMODE
+ BEGIN_FTR_SECTION
+ stb r10,PACAHSRR_VALID(r13)
+ FTR_SECTION_ELSE
+ stb r10,PACASRR_VALID(r13)
+ ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
+ .elseif IHSRR
+ stb r10,PACAHSRR_VALID(r13)
+ .else
+ stb r10,PACASRR_VALID(r13)
+ .endif
+
.if ISET_RI
li r10,MSR_RI
mtmsrd r10,1 /* Set MSR_RI */
@@ -666,10 +680,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
.macro EXCEPTION_RESTORE_REGS hsrr=0
/* Move original SRR0 and SRR1 into the respective regs */
ld r9,_MSR(r1)
+ li r10,0
.if \hsrr
mtspr SPRN_HSRR1,r9
+ stb r10,PACAHSRR_VALID(r13)
.else
mtspr SPRN_SRR1,r9
+ stb r10,PACASRR_VALID(r13)
.endif
ld r9,_NIP(r1)
.if \hsrr
@@ -1781,6 +1798,8 @@ EXC_COMMON_BEGIN(hdecrementer_common)
*
* Be careful to avoid touching the kernel stack.
*/
+ li r10,0
+ stb r10,PACAHSRR_VALID(r13)
ld r10,PACA_EXGEN+EX_CTR(r13)
mtctr r10
mtcrf 0x80,r9
@@ -2611,6 +2630,8 @@ BEGIN_FTR_SECTION
ld r10,PACA_EXGEN+EX_CFAR(r13)
mtspr SPRN_CFAR,r10
END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
+ li r10,0
+ stb r10,PACAHSRR_VALID(r13)
ld r10,PACA_EXGEN+EX_R10(r13)
ld r11,PACA_EXGEN+EX_R11(r13)
ld r12,PACA_EXGEN+EX_R12(r13)
@@ -2783,6 +2804,12 @@ masked_interrupt:
ori r11,r11,PACA_IRQ_HARD_DIS
stb r11,PACAIRQHAPPENED(r13)
2: /* done */
+ li r10,0
+ .if \hsrr
+ stb r10,PACAHSRR_VALID(r13)
+ .else
+ stb r10,PACASRR_VALID(r13)
+ .endif
ld r10,PACA_EXGEN+EX_CTR(r13)
mtctr r10
mtcrf 0x80,r9
diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S
index 3ff9a8fafa46..ae80b4a3da48 100644
--- a/arch/powerpc/kernel/fpu.S
+++ b/arch/powerpc/kernel/fpu.S
@@ -105,6 +105,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
ori r12,r12,MSR_FP
or r12,r12,r4
std r12,_MSR(r1)
+ li r4,0
+ stb r4,PACASRR_VALID(r13)
#endif
li r4,1
stb r4,THREAD_LOAD_FP(r5)
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 409080208a6c..dcac6c74a93c 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -147,7 +147,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs)
return 0;
if (*(u32 *)regs->nip == BREAK_INSTR)
- regs->nip += BREAK_INSTR_SIZE;
+ regs_add_return_ip(regs, BREAK_INSTR_SIZE);
return 1;
}
diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c
index 972cb28174b2..dc35d4f5564f 100644
--- a/arch/powerpc/kernel/kprobes-ftrace.c
+++ b/arch/powerpc/kernel/kprobes-ftrace.c
@@ -40,7 +40,7 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
* Emulate singlestep (and also recover regs->nip)
* as if there is a nop
*/
- regs->nip += MCOUNT_INSN_SIZE;
+ regs_add_return_ip(regs, MCOUNT_INSN_SIZE);
if (unlikely(p->post_handler)) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
p->post_handler(p, regs, 0);
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 01ab2163659e..8165ed71ab51 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -178,7 +178,7 @@ static nokprobe_inline void prepare_singlestep(struct kprobe *p, struct pt_regs
* variant as values in regs could play a part in
* if the trap is taken or not
*/
- regs->nip = (unsigned long)p->ainsn.insn;
+ regs_set_return_ip(regs, (unsigned long)p->ainsn.insn);
}
static nokprobe_inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
@@ -415,7 +415,7 @@ static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
* we end up emulating it in kprobe_handler(), which increments the nip
* again.
*/
- regs->nip = orig_ret_address - 4;
+ regs_set_return_ip(regs, orig_ret_address - 4);
regs->link = orig_ret_address;
return 0;
@@ -450,7 +450,7 @@ int kprobe_post_handler(struct pt_regs *regs)
}
/* Adjust nip to after the single-stepped instruction */
- regs->nip = (unsigned long)cur->addr + len;
+ regs_set_return_ip(regs, (unsigned long)cur->addr + len);
regs->msr |= kcb->kprobe_saved_msr;
/*Restore back the original saved kprobes variables and continue. */
@@ -490,7 +490,7 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
* and allow the page fault handler to continue as a
* normal page fault.
*/
- regs->nip = (unsigned long)cur->addr;
+ regs_set_return_ip(regs, (unsigned long)cur->addr);
regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */
regs->msr |= kcb->kprobe_saved_msr;
if (kcb->kprobe_status == KPROBE_REENTER)
@@ -523,7 +523,7 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
* zero, try to fix up.
*/
if ((entry = search_exception_tables(regs->nip)) != NULL) {
- regs->nip = extable_fixup(entry);
+ regs_set_return_ip(regs, extable_fixup(entry));
return 1;
}
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 0bdd3ed653df..ea36a29c8b01 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -97,6 +97,8 @@ static void check_if_tm_restore_required(struct task_struct *tsk)
!test_thread_flag(TIF_RESTORE_TM)) {
tsk->thread.ckpt_regs.msr = tsk->thread.regs->msr;
set_thread_flag(TIF_RESTORE_TM);
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
}
}
@@ -161,6 +163,8 @@ static void __giveup_fpu(struct task_struct *tsk)
if (cpu_has_feature(CPU_FTR_VSX))
msr &= ~MSR_VSX;
tsk->thread.regs->msr = msr;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
}
void giveup_fpu(struct task_struct *tsk)
@@ -244,6 +248,8 @@ static void __giveup_altivec(struct task_struct *tsk)
if (cpu_has_feature(CPU_FTR_VSX))
msr &= ~MSR_VSX;
tsk->thread.regs->msr = msr;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
}
void giveup_altivec(struct task_struct *tsk)
@@ -559,6 +565,8 @@ void notrace restore_math(struct pt_regs *regs)
msr_check_and_clear(new_msr);
regs->msr |= new_msr | fpexc_mode;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
}
}
#endif /* CONFIG_PPC_BOOK3S_64 */
@@ -1295,6 +1303,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
atomic_read(¤t->mm->context.vas_windows)))
asm volatile(PPC_CP_ABORT);
}
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
#endif /* CONFIG_PPC_BOOK3S_64 */
return last;
@@ -1878,6 +1888,9 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
thread_pkey_regs_init(¤t->thread);
+
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
}
EXPORT_SYMBOL(start_thread);
@@ -1925,9 +1938,12 @@ int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
if (val > PR_FP_EXC_PRECISE)
return -EINVAL;
tsk->thread.fpexc_mode = __pack_fe01(val);
- if (regs != NULL && (regs->msr & MSR_FP) != 0)
+ if (regs != NULL && (regs->msr & MSR_FP) != 0) {
regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
| tsk->thread.fpexc_mode;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+ }
return 0;
}
@@ -1979,6 +1995,9 @@ int set_endian(struct task_struct *tsk, unsigned int val)
else
return -EINVAL;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
return 0;
}
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 954f41676f69..85b5541a24f7 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -46,6 +46,13 @@
/* This is here deliberately so it's only used in this file */
void enter_rtas(unsigned long);
+static inline void do_enter_rtas(unsigned long args)
+{
+ enter_rtas(args);
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+}
+
struct rtas_t rtas = {
.lock = __ARCH_SPIN_LOCK_UNLOCKED
};
@@ -384,7 +391,7 @@ static char *__fetch_rtas_last_error(char *altbuf)
save_args = rtas.args;
rtas.args = err_args;
- enter_rtas(__pa(&rtas.args));
+ do_enter_rtas(__pa(&rtas.args));
err_args = rtas.args;
rtas.args = save_args;
@@ -430,7 +437,7 @@ va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret,
for (i = 0; i < nret; ++i)
args->rets[i] = 0;
- enter_rtas(__pa(args));
+ do_enter_rtas(__pa(args));
}
void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...)
@@ -1198,7 +1205,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
flags = lock_rtas();
rtas.args = args;
- enter_rtas(__pa(&rtas.args));
+ do_enter_rtas(__pa(&rtas.args));
args = rtas.args;
/* A -1 return code indicates that the last command couldn't
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 44ec7b34b27e..ca1a504d442d 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -242,7 +242,7 @@ static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
regs->gpr[0] = __NR_restart_syscall;
else
regs->gpr[3] = regs->orig_gpr3;
- regs->nip -= 4;
+ regs_add_return_ip(regs, - 4);
regs->result = 0;
} else {
if (trap_is_scv(regs)) {
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index bfc939360bad..8e60c89dcc87 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -693,6 +693,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
/* This returns like rt_sigreturn */
set_thread_flag(TIF_RESTOREALL);
+
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
return 0;
}
@@ -798,6 +802,10 @@ SYSCALL_DEFINE0(rt_sigreturn)
goto badframe;
set_thread_flag(TIF_RESTOREALL);
+
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
return 0;
badframe:
@@ -878,6 +886,7 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
/* Set up "regs" so we "return" to the signal handler. */
+ /* XXX: use set return IP */
if (is_elf2_task()) {
regs->ctr = (unsigned long) ksig->ka.sa.sa_handler;
regs->gpr[12] = regs->ctr;
@@ -910,6 +919,9 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
if (err)
goto badframe;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
return 0;
badframe:
@@ -917,6 +929,8 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
tsk->comm, tsk->pid, "setup_rt_frame",
(long)frame, regs->nip, regs->link);
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
return 1;
}
diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index 078608ec2e92..13bf62ccfa18 100644
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -123,6 +123,8 @@ SYSCALL_DEFINE0(switch_endian)
struct thread_info *ti;
current->thread.regs->msr ^= MSR_LE;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
/*
* Set TIF_RESTOREALL so that r3 isn't clobbered on return to
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 95f84c542523..0796391edd16 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1049,7 +1049,7 @@ static void p9_hmi_special_emu(struct pt_regs *regs)
#endif /* !__LITTLE_ENDIAN__ */
/* Go to next instruction */
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
}
#endif /* CONFIG_VSX */
@@ -1487,7 +1487,7 @@ DEFINE_INTERRUPT_HANDLER(program_check_exception)
if (!(regs->msr & MSR_PR) && /* not user-mode */
report_bug(bugaddr, regs) == BUG_TRAP_TYPE_WARN) {
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
return;
}
_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
@@ -1549,7 +1549,7 @@ DEFINE_INTERRUPT_HANDLER(program_check_exception)
if (reason & (REASON_ILLEGAL | REASON_PRIVILEGED)) {
switch (emulate_instruction(regs)) {
case 0:
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
emulate_single_step(regs);
return;
case -EFAULT:
@@ -1600,7 +1600,7 @@ DEFINE_INTERRUPT_HANDLER(alignment_exception)
if (fixed == 1) {
/* skip over emulated instruction */
- regs->nip += inst_length(reason);
+ regs_add_return_ip(regs, inst_length(reason));
emulate_single_step(regs);
return;
}
@@ -1767,7 +1767,7 @@ DEFINE_INTERRUPT_HANDLER(facility_unavailable_exception)
pr_err("DSCR based mfspr emulation failed\n");
return;
}
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
emulate_single_step(regs);
}
return;
@@ -2030,7 +2030,7 @@ DEFINE_INTERRUPT_HANDLER(altivec_assist_exception)
PPC_WARN_EMULATED(altivec, regs);
err = emulate_altivec(regs);
if (err == 0) {
- regs->nip += 4; /* skip emulated instruction */
+ regs_add_return_ip(regs, 4); /* skip emulated instruction */
emulate_single_step(regs);
return;
}
@@ -2094,7 +2094,7 @@ void SPEFloatingPointException(struct pt_regs *regs)
err = do_spe_mathemu(regs);
if (err == 0) {
- regs->nip += 4; /* skip emulated instruction */
+ regs_add_return_ip(regs, 4); /* skip emulated instruction */
emulate_single_step(regs);
return;
}
@@ -2125,10 +2125,10 @@ void SPEFloatingPointRoundException(struct pt_regs *regs)
giveup_spe(current);
preempt_enable();
- regs->nip -= 4;
+ regs_add_return_ip(regs, - 4);
err = speround_handler(regs);
if (err == 0) {
- regs->nip += 4; /* skip emulated instruction */
+ regs_add_return_ip(regs, 4); /* skip emulated instruction */
emulate_single_step(regs);
return;
}
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 2c948e7b0d00..609e3526a66f 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -75,6 +75,8 @@ _GLOBAL(load_up_altivec)
addi r5,r4,THREAD /* Get THREAD */
oris r12,r12,MSR_VEC@h
std r12,_MSR(r1)
+ li r4,0
+ stb r4,PACASRR_VALID(r13)
#endif
li r4,1
stb r4,THREAD_LOAD_VEC(r5)
@@ -133,6 +135,8 @@ _GLOBAL(load_up_vsx)
/* enable use of VSX after return */
oris r12,r12,MSR_VSX@h
std r12,_MSR(r1)
+ li r4,0
+ stb r4,PACASRR_VALID(r13)
b fast_interrupt_return_srr
#endif /* CONFIG_VSX */
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 855457ed09b5..6c2d6a3c9c8a 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -3033,7 +3033,7 @@ void emulate_update_regs(struct pt_regs *regs, struct instruction_op *op)
default:
WARN_ON_ONCE(1);
}
- regs->nip = next_pc;
+ regs_set_return_ip(regs, next_pc);
}
NOKPROBE_SYMBOL(emulate_update_regs);
@@ -3310,6 +3310,9 @@ int emulate_step(struct pt_regs *regs, struct ppc_inst instr)
unsigned long val;
unsigned long ea;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
r = analyse_instr(&op, regs, instr);
if (r < 0)
return r;
diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c
index 30b4b69c6941..d92416d78aee 100644
--- a/arch/powerpc/math-emu/math.c
+++ b/arch/powerpc/math-emu/math.c
@@ -453,7 +453,7 @@ do_mathemu(struct pt_regs *regs)
break;
}
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
return 0;
illegal:
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 1999982200ab..1d82dc53386f 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -615,7 +615,7 @@ void bad_page_fault(struct pt_regs *regs, int sig)
/* Are we prepared to handle this fault? */
if ((entry = search_exception_tables(regs->nip)) != NULL) {
- regs->nip = extable_fixup(entry);
+ regs_set_return_ip(regs, extable_fixup(entry));
return;
}
diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
index 5cd0f52d258f..1a7bc261d156 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -100,6 +100,9 @@ static int64_t opal_call(int64_t a0, int64_t a1, int64_t a2, int64_t a3,
bool mmu = (msr & (MSR_IR|MSR_DR));
int64_t ret;
+ local_paca->hsrr_valid = 0;
+ local_paca->srr_valid = 0;
+
msr &= ~MSR_EE;
if (unlikely(!mmu))
diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
index 040b9d01c079..af78e7c3108f 100644
--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c
@@ -1072,7 +1072,7 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
ret = get_kernel_nofault(inst, (void *)regs->nip);
if (!ret && mcheck_handle_load(regs, inst)) {
- regs->nip += 4;
+ regs_add_return_ip(regs, 4);
return 1;
}
}
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 5/9] powerpc/64: move interrupt return asm to interrupt_64.S
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (3 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 4/9] powerpc/64s: avoid reloading (H)SRR registers if they are still valid Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 6/9] powerpc/64s: save one more register in the masked interrupt handler Nicholas Piggin
` (4 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
The next patch would like to move interrupt return assembly code to a low
location before general text, so move it into its own file and include via
head_64.S
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/head-64.h | 2 +-
arch/powerpc/kernel/entry_64.S | 601 ----------------------------
arch/powerpc/kernel/head_64.S | 5 +-
arch/powerpc/kernel/interrupt_64.S | 608 +++++++++++++++++++++++++++++
4 files changed, 613 insertions(+), 603 deletions(-)
create mode 100644 arch/powerpc/kernel/interrupt_64.S
diff --git a/arch/powerpc/include/asm/head-64.h b/arch/powerpc/include/asm/head-64.h
index 4cb9efa2eb21..242204e12993 100644
--- a/arch/powerpc/include/asm/head-64.h
+++ b/arch/powerpc/include/asm/head-64.h
@@ -16,7 +16,7 @@
.section ".head.data.\name\()","a",@progbits
.endm
.macro use_ftsec name
- .section ".head.text.\name\()"
+ .section ".head.text.\name\()","ax",@progbits
.endm
/*
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 6236a88a592f..65ddd159974b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -32,7 +32,6 @@
#include <asm/irqflags.h>
#include <asm/hw_irq.h>
#include <asm/context_tracking.h>
-#include <asm/tm.h>
#include <asm/ppc-opcode.h>
#include <asm/barrier.h>
#include <asm/export.h>
@@ -48,411 +47,7 @@
/*
* System calls.
*/
- .section ".toc","aw"
-SYS_CALL_TABLE:
- .tc sys_call_table[TC],sys_call_table
-
-#ifdef CONFIG_COMPAT
-COMPAT_SYS_CALL_TABLE:
- .tc compat_sys_call_table[TC],compat_sys_call_table
-#endif
-
-/* This value is used to mark exception frames on the stack. */
-exception_marker:
- .tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER
-
.section ".text"
- .align 7
-
-#ifdef CONFIG_PPC_BOOK3S
-.macro DEBUG_SRR_VALID srr
-#ifdef CONFIG_PPC_RFI_SRR_DEBUG
- .ifc \srr,srr
- mfspr r11,SPRN_SRR0
- ld r12,_NIP(r1)
-100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
- mfspr r11,SPRN_SRR1
- ld r12,_MSR(r1)
-100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
- .else
- mfspr r11,SPRN_HSRR0
- ld r12,_NIP(r1)
-100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
- mfspr r11,SPRN_HSRR1
- ld r12,_MSR(r1)
-100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
- .endif
-#endif
-.endm
-
-.macro system_call_vectored name trapnr
- .globl system_call_vectored_\name
-system_call_vectored_\name:
-_ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-BEGIN_FTR_SECTION
- extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
- bne .Ltabort_syscall
-END_FTR_SECTION_IFSET(CPU_FTR_TM)
-#endif
- INTERRUPT_TO_KERNEL
- mr r10,r1
- ld r1,PACAKSAVE(r13)
- std r10,0(r1)
- std r11,_NIP(r1)
- std r12,_MSR(r1)
- std r0,GPR0(r1)
- std r10,GPR1(r1)
- std r2,GPR2(r1)
- ld r2,PACATOC(r13)
- mfcr r12
- li r11,0
- /* Can we avoid saving r3-r8 in common case? */
- std r3,GPR3(r1)
- std r4,GPR4(r1)
- std r5,GPR5(r1)
- std r6,GPR6(r1)
- std r7,GPR7(r1)
- std r8,GPR8(r1)
- /* Zero r9-r12, this should only be required when restoring all GPRs */
- std r11,GPR9(r1)
- std r11,GPR10(r1)
- std r11,GPR11(r1)
- std r11,GPR12(r1)
- std r9,GPR13(r1)
- SAVE_NVGPRS(r1)
- std r11,_XER(r1)
- std r11,_LINK(r1)
- std r11,_CTR(r1)
-
- li r11,\trapnr
- std r11,_TRAP(r1)
- std r12,_CCR(r1)
- std r3,ORIG_GPR3(r1)
- addi r10,r1,STACK_FRAME_OVERHEAD
- ld r11,exception_marker@toc(r2)
- std r11,-16(r10) /* "regshere" marker */
-
-BEGIN_FTR_SECTION
- HMT_MEDIUM
-END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-
- /*
- * RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
- * would clobber syscall parameters. Also we always enter with IRQs
- * enabled and nothing pending. system_call_exception() will call
- * trace_hardirqs_off().
- *
- * scv enters with MSR[EE]=1, so don't set PACA_IRQ_HARD_DIS. The
- * entry vector already sets PACAIRQSOFTMASK to IRQS_ALL_DISABLED.
- */
-
- /* Calling convention has r9 = orig r0, r10 = regs */
- mr r9,r0
- bl system_call_exception
-
-.Lsyscall_vectored_\name\()_exit:
- addi r4,r1,STACK_FRAME_OVERHEAD
- li r5,1 /* scv */
- bl syscall_exit_prepare
-
- ld r2,_CCR(r1)
- ld r4,_NIP(r1)
- ld r5,_MSR(r1)
-
-BEGIN_FTR_SECTION
- stdcx. r0,0,r1 /* to clear the reservation */
-END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
-
-BEGIN_FTR_SECTION
- HMT_MEDIUM_LOW
-END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-
- cmpdi r3,0
- bne .Lsyscall_vectored_\name\()_restore_regs
-
- /* rfscv returns with LR->NIA and CTR->MSR */
- mtlr r4
- mtctr r5
-
- /* Could zero these as per ABI, but we may consider a stricter ABI
- * which preserves these if libc implementations can benefit, so
- * restore them for now until further measurement is done. */
- ld r0,GPR0(r1)
- ld r4,GPR4(r1)
- ld r5,GPR5(r1)
- ld r6,GPR6(r1)
- ld r7,GPR7(r1)
- ld r8,GPR8(r1)
- /* Zero volatile regs that may contain sensitive kernel data */
- li r9,0
- li r10,0
- li r11,0
- li r12,0
- mtspr SPRN_XER,r0
-
- /*
- * We don't need to restore AMR on the way back to userspace for KUAP.
- * The value of AMR only matters while we're in the kernel.
- */
- mtcr r2
- ld r2,GPR2(r1)
- ld r3,GPR3(r1)
- ld r13,GPR13(r1)
- ld r1,GPR1(r1)
- RFSCV_TO_USER
- b . /* prevent speculative execution */
-
-.Lsyscall_vectored_\name\()_restore_regs:
- li r3,0
- mtmsrd r3,1
- mtspr SPRN_SRR0,r4
- mtspr SPRN_SRR1,r5
-
- ld r3,_CTR(r1)
- ld r4,_LINK(r1)
- ld r5,_XER(r1)
-
- REST_NVGPRS(r1)
- ld r0,GPR0(r1)
- mtcr r2
- mtctr r3
- mtlr r4
- mtspr SPRN_XER,r5
- REST_10GPRS(2, r1)
- REST_2GPRS(12, r1)
- ld r1,GPR1(r1)
- RFI_TO_USER
-.endm
-
-system_call_vectored common 0x3000
-/*
- * We instantiate another entry copy for the SIGILL variant, with TRAP=0x7ff0
- * which is tested by system_call_exception when r0 is -1 (as set by vector
- * entry code).
- */
-system_call_vectored sigill 0x7ff0
-
-
-/*
- * Entered via kernel return set up by kernel/sstep.c, must match entry regs
- */
- .globl system_call_vectored_emulate
-system_call_vectored_emulate:
-_ASM_NOKPROBE_SYMBOL(system_call_vectored_emulate)
- li r10,IRQS_ALL_DISABLED
- stb r10,PACAIRQSOFTMASK(r13)
- b system_call_vectored_common
-#endif
-
- .balign IFETCH_ALIGN_BYTES
- .globl system_call_common_real
-system_call_common_real:
- ld r10,PACAKMSR(r13) /* get MSR value for kernel */
- mtmsrd r10
-
- .balign IFETCH_ALIGN_BYTES
- .globl system_call_common
-system_call_common:
-_ASM_NOKPROBE_SYMBOL(system_call_common)
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-BEGIN_FTR_SECTION
- extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
- bne .Ltabort_syscall
-END_FTR_SECTION_IFSET(CPU_FTR_TM)
-#endif
- mr r10,r1
- ld r1,PACAKSAVE(r13)
- std r10,0(r1)
- std r11,_NIP(r1)
- std r12,_MSR(r1)
- std r0,GPR0(r1)
- std r10,GPR1(r1)
- std r2,GPR2(r1)
-#ifdef CONFIG_PPC_FSL_BOOK3E
-START_BTB_FLUSH_SECTION
- BTB_FLUSH(r10)
-END_BTB_FLUSH_SECTION
-#endif
- ld r2,PACATOC(r13)
- mfcr r12
- li r11,0
- /* Can we avoid saving r3-r8 in common case? */
- std r3,GPR3(r1)
- std r4,GPR4(r1)
- std r5,GPR5(r1)
- std r6,GPR6(r1)
- std r7,GPR7(r1)
- std r8,GPR8(r1)
- /* Zero r9-r12, this should only be required when restoring all GPRs */
- std r11,GPR9(r1)
- std r11,GPR10(r1)
- std r11,GPR11(r1)
- std r11,GPR12(r1)
- std r9,GPR13(r1)
- SAVE_NVGPRS(r1)
- std r11,_XER(r1)
- std r11,_CTR(r1)
- mflr r10
-
- /*
- * This clears CR0.SO (bit 28), which is the error indication on
- * return from this system call.
- */
- rldimi r12,r11,28,(63-28)
- li r11,0xc00
- std r10,_LINK(r1)
- std r11,_TRAP(r1)
- std r12,_CCR(r1)
- std r3,ORIG_GPR3(r1)
- addi r10,r1,STACK_FRAME_OVERHEAD
- ld r11,exception_marker@toc(r2)
- std r11,-16(r10) /* "regshere" marker */
-
- li r11,1
- stb r11,PACASRR_VALID(r13)
-
- /*
- * RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
- * would clobber syscall parameters. Also we always enter with IRQs
- * enabled and nothing pending. system_call_exception() will call
- * trace_hardirqs_off().
- */
- li r11,IRQS_ALL_DISABLED
- li r12,PACA_IRQ_HARD_DIS
- stb r11,PACAIRQSOFTMASK(r13)
- stb r12,PACAIRQHAPPENED(r13)
-
- /* Calling convention has r9 = orig r0, r10 = regs */
- mr r9,r0
- bl system_call_exception
-
-.Lsyscall_exit:
- addi r4,r1,STACK_FRAME_OVERHEAD
- li r5,0 /* !scv */
- bl syscall_exit_prepare
-
- ld r2,_CCR(r1)
- ld r6,_LINK(r1)
- mtlr r6
-
- lbz r4,PACASRR_VALID(r13)
- cmpdi r4,0
- bne 1f
- li r4,0
- stb r4,PACASRR_VALID(r13)
- ld r4,_NIP(r1)
- ld r5,_MSR(r1)
- mtspr SPRN_SRR0,r4
- mtspr SPRN_SRR1,r5
-1:
- DEBUG_SRR_VALID srr
-
-BEGIN_FTR_SECTION
- stdcx. r0,0,r1 /* to clear the reservation */
-END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
-
- cmpdi r3,0
- bne .Lsyscall_restore_regs
- /* Zero volatile regs that may contain sensitive kernel data */
- li r0,0
- li r4,0
- li r5,0
- li r6,0
- li r7,0
- li r8,0
- li r9,0
- li r10,0
- li r11,0
- li r12,0
- mtctr r0
- mtspr SPRN_XER,r0
-.Lsyscall_restore_regs_cont:
-
-BEGIN_FTR_SECTION
- HMT_MEDIUM_LOW
-END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-
- /*
- * We don't need to restore AMR on the way back to userspace for KUAP.
- * The value of AMR only matters while we're in the kernel.
- */
- mtcr r2
- ld r2,GPR2(r1)
- ld r3,GPR3(r1)
- ld r13,GPR13(r1)
- ld r1,GPR1(r1)
- RFI_TO_USER
- b . /* prevent speculative execution */
-
-.Lsyscall_restore_regs:
- ld r3,_CTR(r1)
- ld r4,_XER(r1)
- REST_NVGPRS(r1)
- mtctr r3
- mtspr SPRN_XER,r4
- ld r0,GPR0(r1)
- REST_8GPRS(4, r1)
- ld r12,GPR12(r1)
- b .Lsyscall_restore_regs_cont
-
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-.Ltabort_syscall:
- /* Firstly we need to enable TM in the kernel */
- mfmsr r10
- li r9, 1
- rldimi r10, r9, MSR_TM_LG, 63-MSR_TM_LG
- mtmsrd r10, 0
-
- /* tabort, this dooms the transaction, nothing else */
- li r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
- TABORT(R9)
-
- /*
- * Return directly to userspace. We have corrupted user register state,
- * but userspace will never see that register state. Execution will
- * resume after the tbegin of the aborted transaction with the
- * checkpointed register state.
- */
- li r9, MSR_RI
- andc r10, r10, r9
- mtmsrd r10, 1
- mtspr SPRN_SRR0, r11
- mtspr SPRN_SRR1, r12
- RFI_TO_USER
- b . /* prevent speculative execution */
-#endif
-
-#ifdef CONFIG_PPC_BOOK3S
-_GLOBAL(ret_from_fork_scv)
- bl schedule_tail
- REST_NVGPRS(r1)
- li r3,0 /* fork() return value */
- b .Lsyscall_vectored_common_exit
-#endif
-
-_GLOBAL(ret_from_fork)
- bl schedule_tail
- REST_NVGPRS(r1)
- li r3,0 /* fork() return value */
- b .Lsyscall_exit
-
-_GLOBAL(ret_from_kernel_thread)
- bl schedule_tail
- REST_NVGPRS(r1)
- mtctr r14
- mr r3,r15
-#ifdef PPC64_ELF_ABI_v2
- mr r12,r14
-#endif
- bctrl
- li r3,0
- b .Lsyscall_exit
-
#ifdef CONFIG_PPC_BOOK3E
/* Save non-volatile GPRs, if not already saved. */
_GLOBAL(save_nvgprs)
@@ -681,202 +276,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
addi r1,r1,SWITCH_FRAME_SIZE
blr
-#ifdef CONFIG_PPC_BOOK3S
- /*
- * If MSR EE/RI was never enabled, IRQs not reconciled, NVGPRs not
- * touched, no exit work created, then this can be used.
- */
- .balign IFETCH_ALIGN_BYTES
- .globl fast_interrupt_return_srr
-fast_interrupt_return_srr:
-_ASM_NOKPROBE_SYMBOL(fast_interrupt_return_srr)
- kuap_check_amr r3, r4
- ld r5,_MSR(r1)
- andi. r0,r5,MSR_PR
- bne .Lfast_user_interrupt_return_srr
- kuap_restore_amr r3, r4
- andi. r0,r5,MSR_RI
- li r3,0 /* 0 return value, no EMULATE_STACK_STORE */
- bne+ .Lfast_kernel_interrupt_return_srr
- addi r3,r1,STACK_FRAME_OVERHEAD
- bl unrecoverable_exception
- b . /* should not get here */
-
-.macro interrupt_return_macro srr
- .balign IFETCH_ALIGN_BYTES
- .globl interrupt_return_\srr
-interrupt_return_\srr\():
-_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
- ld r4,_MSR(r1)
- andi. r0,r4,MSR_PR
- beq .Lkernel_interrupt_return_\srr
- addi r3,r1,STACK_FRAME_OVERHEAD
- bl interrupt_exit_user_prepare
- cmpdi r3,0
- bne- .Lrestore_nvgprs_\srr
-
-.Lfast_user_interrupt_return_\srr:
-BEGIN_FTR_SECTION
- ld r10,_PPR(r1)
- mtspr SPRN_PPR,r10
-END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
- .ifc \srr,srr
- lbz r4,PACASRR_VALID(r13)
- .else
- lbz r4,PACAHSRR_VALID(r13)
- .endif
- cmpdi r4,0
- li r4,0
- bne 1f
- ld r11,_NIP(r1)
- ld r12,_MSR(r1)
- .ifc \srr,srr
- mtspr SPRN_SRR0,r11
- mtspr SPRN_SRR1,r12
-1:
- stb r4,PACASRR_VALID(r13)
- .else
- mtspr SPRN_HSRR0,r11
- mtspr SPRN_HSRR1,r12
-1:
- stb r4,PACAHSRR_VALID(r13)
- .endif
- DEBUG_SRR_VALID \srr
-
-BEGIN_FTR_SECTION
- stdcx. r0,0,r1 /* to clear the reservation */
-FTR_SECTION_ELSE
- ldarx r0,0,r1
-ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
-
- ld r3,_CCR(r1)
- ld r4,_LINK(r1)
- ld r5,_CTR(r1)
- ld r6,_XER(r1)
- li r0,0
-
- REST_4GPRS(7, r1)
- REST_2GPRS(11, r1)
- REST_GPR(13, r1)
-
- mtcr r3
- mtlr r4
- mtctr r5
- mtspr SPRN_XER,r6
-
- REST_4GPRS(2, r1)
- REST_GPR(6, r1)
- REST_GPR(0, r1)
- REST_GPR(1, r1)
- .ifc \srr,srr
- RFI_TO_USER
- .else
- HRFI_TO_USER
- .endif
- b . /* prevent speculative execution */
-
-.Lrestore_nvgprs_\srr\():
- REST_NVGPRS(r1)
- b .Lfast_user_interrupt_return_\srr
-
- .balign IFETCH_ALIGN_BYTES
-.Lkernel_interrupt_return_\srr\():
- addi r3,r1,STACK_FRAME_OVERHEAD
- bl interrupt_exit_kernel_prepare
-
-.Lfast_kernel_interrupt_return_\srr\():
- cmpdi cr1,r3,0
- .ifc \srr,srr
- lbz r4,PACASRR_VALID(r13)
- .else
- lbz r4,PACAHSRR_VALID(r13)
- .endif
- cmpdi r4,0
- li r4,0
- bne 1f
- ld r11,_NIP(r1)
- ld r12,_MSR(r1)
- .ifc \srr,srr
- mtspr SPRN_SRR0,r11
- mtspr SPRN_SRR1,r12
-1:
- stb r4,PACASRR_VALID(r13)
- .else
- mtspr SPRN_HSRR0,r11
- mtspr SPRN_HSRR1,r12
-1:
- stb r4,PACAHSRR_VALID(r13)
- .endif
- DEBUG_SRR_VALID \srr
-
-BEGIN_FTR_SECTION
- stdcx. r0,0,r1 /* to clear the reservation */
-FTR_SECTION_ELSE
- ldarx r0,0,r1
-ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
-
- ld r3,_LINK(r1)
- ld r4,_CTR(r1)
- ld r5,_XER(r1)
- ld r6,_CCR(r1)
- li r0,0
-
- REST_4GPRS(7, r1)
- REST_2GPRS(11, r1)
-
- mtlr r3
- mtctr r4
- mtspr SPRN_XER,r5
-
- /*
- * Leaving a stale exception_marker on the stack can confuse
- * the reliable stack unwinder later on. Clear it.
- */
- std r0,STACK_FRAME_OVERHEAD-16(r1)
-
- REST_4GPRS(2, r1)
-
- bne- cr1,1f /* emulate stack store */
- mtcr r6
- REST_GPR(6, r1)
- REST_GPR(0, r1)
- REST_GPR(1, r1)
- .ifc \srr,srr
- RFI_TO_KERNEL
- .else
- HRFI_TO_KERNEL
- .endif
- b . /* prevent speculative execution */
-
-1: /*
- * Emulate stack store with update. New r1 value was already calculated
- * and updated in our interrupt regs by emulate_loadstore, but we can't
- * store the previous value of r1 to the stack before re-loading our
- * registers from it, otherwise they could be clobbered. Use
- * PACA_EXGEN as temporary storage to hold the store data, as
- * interrupts are disabled here so it won't be clobbered.
- */
- mtcr r6
- std r9,PACA_EXGEN+0(r13)
- addi r9,r1,INT_FRAME_SIZE /* get original r1 */
- REST_GPR(6, r1)
- REST_GPR(0, r1)
- REST_GPR(1, r1)
- std r9,0(r1) /* perform store component of stdu */
- ld r9,PACA_EXGEN+0(r13)
-
- .ifc \srr,srr
- RFI_TO_KERNEL
- .else
- HRFI_TO_KERNEL
- .endif
- b . /* prevent speculative execution */
-.endm
-
-interrupt_return_macro srr
-interrupt_return_macro hsrr
-#endif /* CONFIG_PPC_BOOK3S */
-
#ifdef CONFIG_PPC_RTAS
/*
* On CHRP, the Run-Time Abstraction Services (RTAS) have to be
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 4e2591cb4bd1..b13a2d79dfb4 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -189,8 +189,9 @@ CLOSE_FIXED_SECTION(first_256B)
/* This value is used to mark exception frames on the stack. */
.section ".toc","aw"
+/* This value is used to mark exception frames on the stack. */
exception_marker:
- .tc ID_72656773_68657265[TC],0x7265677368657265
+ .tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER
.previous
/*
@@ -206,6 +207,8 @@ OPEN_TEXT_SECTION(0x100)
USE_TEXT_SECTION()
+#include "interrupt_64.S"
+
#ifdef CONFIG_PPC_BOOK3E
/*
* The booting_thread_hwid holds the thread id we want to boot in cpu
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
new file mode 100644
index 000000000000..e121829ef717
--- /dev/null
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -0,0 +1,608 @@
+#include <asm/ppc_asm.h>
+#include <asm/head-64.h>
+#include <asm/bug.h>
+#include <asm/hw_irq.h>
+#include <asm/tm.h>
+#include <asm/mmu.h>
+#include <asm/asm-offsets.h>
+#include <asm/exception-64s.h>
+#include <asm/ptrace.h>
+#include <asm/head-64.h>
+#include <asm/feature-fixups.h>
+#include <asm/kup.h>
+
+ .section ".toc","aw"
+SYS_CALL_TABLE:
+ .tc sys_call_table[TC],sys_call_table
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYS_CALL_TABLE:
+ .tc compat_sys_call_table[TC],compat_sys_call_table
+#endif
+ .previous
+
+#ifdef CONFIG_PPC_BOOK3S
+.macro DEBUG_SRR_VALID srr
+#ifdef CONFIG_PPC_RFI_SRR_DEBUG
+ .ifc \srr,srr
+ mfspr r11,SPRN_SRR0
+ ld r12,_NIP(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ mfspr r11,SPRN_SRR1
+ ld r12,_MSR(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ .else
+ mfspr r11,SPRN_HSRR0
+ ld r12,_NIP(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ mfspr r11,SPRN_HSRR1
+ ld r12,_MSR(r1)
+100: tdne r11,r12
+ EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ .endif
+#endif
+.endm
+
+.macro system_call_vectored name trapnr
+ .globl system_call_vectored_\name
+system_call_vectored_\name:
+_ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+BEGIN_FTR_SECTION
+ extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
+ bne .Ltabort_syscall
+END_FTR_SECTION_IFSET(CPU_FTR_TM)
+#endif
+ INTERRUPT_TO_KERNEL
+ mr r10,r1
+ ld r1,PACAKSAVE(r13)
+ std r10,0(r1)
+ std r11,_NIP(r1)
+ std r12,_MSR(r1)
+ std r0,GPR0(r1)
+ std r10,GPR1(r1)
+ std r2,GPR2(r1)
+ ld r2,PACATOC(r13)
+ mfcr r12
+ li r11,0
+ /* Can we avoid saving r3-r8 in common case? */
+ std r3,GPR3(r1)
+ std r4,GPR4(r1)
+ std r5,GPR5(r1)
+ std r6,GPR6(r1)
+ std r7,GPR7(r1)
+ std r8,GPR8(r1)
+ /* Zero r9-r12, this should only be required when restoring all GPRs */
+ std r11,GPR9(r1)
+ std r11,GPR10(r1)
+ std r11,GPR11(r1)
+ std r11,GPR12(r1)
+ std r9,GPR13(r1)
+ SAVE_NVGPRS(r1)
+ std r11,_XER(r1)
+ std r11,_LINK(r1)
+ std r11,_CTR(r1)
+
+ li r11,\trapnr
+ std r11,_TRAP(r1)
+ std r12,_CCR(r1)
+ std r3,ORIG_GPR3(r1)
+ addi r10,r1,STACK_FRAME_OVERHEAD
+ ld r11,exception_marker@toc(r2)
+ std r11,-16(r10) /* "regshere" marker */
+
+BEGIN_FTR_SECTION
+ HMT_MEDIUM
+END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+
+ /*
+ * RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
+ * would clobber syscall parameters. Also we always enter with IRQs
+ * enabled and nothing pending. system_call_exception() will call
+ * trace_hardirqs_off().
+ *
+ * scv enters with MSR[EE]=1, so don't set PACA_IRQ_HARD_DIS. The
+ * entry vector already sets PACAIRQSOFTMASK to IRQS_ALL_DISABLED.
+ */
+
+ /* Calling convention has r9 = orig r0, r10 = regs */
+ mr r9,r0
+ bl system_call_exception
+
+.Lsyscall_vectored_\name\()_exit:
+ addi r4,r1,STACK_FRAME_OVERHEAD
+ li r5,1 /* scv */
+ bl syscall_exit_prepare
+
+ ld r2,_CCR(r1)
+ ld r4,_NIP(r1)
+ ld r5,_MSR(r1)
+
+BEGIN_FTR_SECTION
+ stdcx. r0,0,r1 /* to clear the reservation */
+END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
+
+BEGIN_FTR_SECTION
+ HMT_MEDIUM_LOW
+END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+
+ cmpdi r3,0
+ bne .Lsyscall_vectored_\name\()_restore_regs
+
+ /* rfscv returns with LR->NIA and CTR->MSR */
+ mtlr r4
+ mtctr r5
+
+ /* Could zero these as per ABI, but we may consider a stricter ABI
+ * which preserves these if libc implementations can benefit, so
+ * restore them for now until further measurement is done. */
+ ld r0,GPR0(r1)
+ ld r4,GPR4(r1)
+ ld r5,GPR5(r1)
+ ld r6,GPR6(r1)
+ ld r7,GPR7(r1)
+ ld r8,GPR8(r1)
+ /* Zero volatile regs that may contain sensitive kernel data */
+ li r9,0
+ li r10,0
+ li r11,0
+ li r12,0
+ mtspr SPRN_XER,r0
+
+ /*
+ * We don't need to restore AMR on the way back to userspace for KUAP.
+ * The value of AMR only matters while we're in the kernel.
+ */
+ mtcr r2
+ ld r2,GPR2(r1)
+ ld r3,GPR3(r1)
+ ld r13,GPR13(r1)
+ ld r1,GPR1(r1)
+ RFSCV_TO_USER
+ b . /* prevent speculative execution */
+
+.Lsyscall_vectored_\name\()_restore_regs:
+ li r3,0
+ mtmsrd r3,1
+ mtspr SPRN_SRR0,r4
+ mtspr SPRN_SRR1,r5
+
+ ld r3,_CTR(r1)
+ ld r4,_LINK(r1)
+ ld r5,_XER(r1)
+
+ REST_NVGPRS(r1)
+ ld r0,GPR0(r1)
+ mtcr r2
+ mtctr r3
+ mtlr r4
+ mtspr SPRN_XER,r5
+ REST_10GPRS(2, r1)
+ REST_2GPRS(12, r1)
+ ld r1,GPR1(r1)
+ RFI_TO_USER
+.endm
+
+system_call_vectored common 0x3000
+/*
+ * We instantiate another entry copy for the SIGILL variant, with TRAP=0x7ff0
+ * which is tested by system_call_exception when r0 is -1 (as set by vector
+ * entry code).
+ */
+system_call_vectored sigill 0x7ff0
+
+
+/*
+ * Entered via kernel return set up by kernel/sstep.c, must match entry regs
+ */
+ .globl system_call_vectored_emulate
+system_call_vectored_emulate:
+_ASM_NOKPROBE_SYMBOL(system_call_vectored_emulate)
+ li r10,IRQS_ALL_DISABLED
+ stb r10,PACAIRQSOFTMASK(r13)
+ b system_call_vectored_common
+#endif /* CONFIG_PPC_BOOK3S */
+
+ .balign IFETCH_ALIGN_BYTES
+ .globl system_call_common_real
+system_call_common_real:
+ ld r10,PACAKMSR(r13) /* get MSR value for kernel */
+ mtmsrd r10
+
+ .balign IFETCH_ALIGN_BYTES
+ .globl system_call_common
+system_call_common:
+_ASM_NOKPROBE_SYMBOL(system_call_common)
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+BEGIN_FTR_SECTION
+ extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
+ bne .Ltabort_syscall
+END_FTR_SECTION_IFSET(CPU_FTR_TM)
+#endif
+ mr r10,r1
+ ld r1,PACAKSAVE(r13)
+ std r10,0(r1)
+ std r11,_NIP(r1)
+ std r12,_MSR(r1)
+ std r0,GPR0(r1)
+ std r10,GPR1(r1)
+ std r2,GPR2(r1)
+#ifdef CONFIG_PPC_FSL_BOOK3E
+START_BTB_FLUSH_SECTION
+ BTB_FLUSH(r10)
+END_BTB_FLUSH_SECTION
+#endif
+ ld r2,PACATOC(r13)
+ mfcr r12
+ li r11,0
+ /* Can we avoid saving r3-r8 in common case? */
+ std r3,GPR3(r1)
+ std r4,GPR4(r1)
+ std r5,GPR5(r1)
+ std r6,GPR6(r1)
+ std r7,GPR7(r1)
+ std r8,GPR8(r1)
+ /* Zero r9-r12, this should only be required when restoring all GPRs */
+ std r11,GPR9(r1)
+ std r11,GPR10(r1)
+ std r11,GPR11(r1)
+ std r11,GPR12(r1)
+ std r9,GPR13(r1)
+ SAVE_NVGPRS(r1)
+ std r11,_XER(r1)
+ std r11,_CTR(r1)
+ mflr r10
+
+ /*
+ * This clears CR0.SO (bit 28), which is the error indication on
+ * return from this system call.
+ */
+ rldimi r12,r11,28,(63-28)
+ li r11,0xc00
+ std r10,_LINK(r1)
+ std r11,_TRAP(r1)
+ std r12,_CCR(r1)
+ std r3,ORIG_GPR3(r1)
+ addi r10,r1,STACK_FRAME_OVERHEAD
+ ld r11,exception_marker@toc(r2)
+ std r11,-16(r10) /* "regshere" marker */
+
+ li r11,1
+ stb r11,PACASRR_VALID(r13)
+
+ /*
+ * RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
+ * would clobber syscall parameters. Also we always enter with IRQs
+ * enabled and nothing pending. system_call_exception() will call
+ * trace_hardirqs_off().
+ */
+ li r11,IRQS_ALL_DISABLED
+ li r12,PACA_IRQ_HARD_DIS
+ stb r11,PACAIRQSOFTMASK(r13)
+ stb r12,PACAIRQHAPPENED(r13)
+
+ /* Calling convention has r9 = orig r0, r10 = regs */
+ mr r9,r0
+ bl system_call_exception
+
+.Lsyscall_exit:
+ addi r4,r1,STACK_FRAME_OVERHEAD
+ li r5,0 /* !scv */
+ bl syscall_exit_prepare
+
+ ld r2,_CCR(r1)
+ ld r6,_LINK(r1)
+ mtlr r6
+
+ lbz r4,PACASRR_VALID(r13)
+ cmpdi r4,0
+ bne 1f
+ li r4,0
+ stb r4,PACASRR_VALID(r13)
+ ld r4,_NIP(r1)
+ ld r5,_MSR(r1)
+ mtspr SPRN_SRR0,r4
+ mtspr SPRN_SRR1,r5
+1:
+ DEBUG_SRR_VALID srr
+
+BEGIN_FTR_SECTION
+ stdcx. r0,0,r1 /* to clear the reservation */
+END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
+
+ cmpdi r3,0
+ bne .Lsyscall_restore_regs
+ /* Zero volatile regs that may contain sensitive kernel data */
+ li r0,0
+ li r4,0
+ li r5,0
+ li r6,0
+ li r7,0
+ li r8,0
+ li r9,0
+ li r10,0
+ li r11,0
+ li r12,0
+ mtctr r0
+ mtspr SPRN_XER,r0
+.Lsyscall_restore_regs_cont:
+
+BEGIN_FTR_SECTION
+ HMT_MEDIUM_LOW
+END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+
+ /*
+ * We don't need to restore AMR on the way back to userspace for KUAP.
+ * The value of AMR only matters while we're in the kernel.
+ */
+ mtcr r2
+ ld r2,GPR2(r1)
+ ld r3,GPR3(r1)
+ ld r13,GPR13(r1)
+ ld r1,GPR1(r1)
+ RFI_TO_USER
+ b . /* prevent speculative execution */
+
+.Lsyscall_restore_regs:
+ ld r3,_CTR(r1)
+ ld r4,_XER(r1)
+ REST_NVGPRS(r1)
+ mtctr r3
+ mtspr SPRN_XER,r4
+ ld r0,GPR0(r1)
+ REST_8GPRS(4, r1)
+ ld r12,GPR12(r1)
+ b .Lsyscall_restore_regs_cont
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+.Ltabort_syscall:
+ /* Firstly we need to enable TM in the kernel */
+ mfmsr r10
+ li r9, 1
+ rldimi r10, r9, MSR_TM_LG, 63-MSR_TM_LG
+ mtmsrd r10, 0
+
+ /* tabort, this dooms the transaction, nothing else */
+ li r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
+ TABORT(R9)
+
+ /*
+ * Return directly to userspace. We have corrupted user register state,
+ * but userspace will never see that register state. Execution will
+ * resume after the tbegin of the aborted transaction with the
+ * checkpointed register state.
+ */
+ li r9, MSR_RI
+ andc r10, r10, r9
+ mtmsrd r10, 1
+ mtspr SPRN_SRR0, r11
+ mtspr SPRN_SRR1, r12
+ RFI_TO_USER
+ b . /* prevent speculative execution */
+#endif
+
+#ifdef CONFIG_PPC_BOOK3S
+_GLOBAL(ret_from_fork_scv)
+ bl schedule_tail
+ REST_NVGPRS(r1)
+ li r3,0 /* fork() return value */
+ b .Lsyscall_vectored_common_exit
+#endif
+
+_GLOBAL(ret_from_fork)
+ bl schedule_tail
+ REST_NVGPRS(r1)
+ li r3,0 /* fork() return value */
+ b .Lsyscall_exit
+
+_GLOBAL(ret_from_kernel_thread)
+ bl schedule_tail
+ REST_NVGPRS(r1)
+ mtctr r14
+ mr r3,r15
+#ifdef PPC64_ELF_ABI_v2
+ mr r12,r14
+#endif
+ bctrl
+ li r3,0
+ b .Lsyscall_exit
+
+#ifdef CONFIG_PPC_BOOK3S
+ /*
+ * If MSR EE/RI was never enabled, IRQs not reconciled, NVGPRs not
+ * touched, no exit work created, then this can be used.
+ */
+ .balign IFETCH_ALIGN_BYTES
+ .globl fast_interrupt_return_srr
+fast_interrupt_return_srr:
+_ASM_NOKPROBE_SYMBOL(fast_interrupt_return_srr)
+ kuap_check_amr r3, r4
+ ld r5,_MSR(r1)
+ andi. r0,r5,MSR_PR
+ bne .Lfast_user_interrupt_return_srr
+ kuap_restore_amr r3, r4
+ andi. r0,r5,MSR_RI
+ li r3,0 /* 0 return value, no EMULATE_STACK_STORE */
+ bne+ .Lfast_kernel_interrupt_return_srr
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl unrecoverable_exception
+ b . /* should not get here */
+
+.macro interrupt_return_macro srr
+ .balign IFETCH_ALIGN_BYTES
+ .globl interrupt_return_\srr
+interrupt_return_\srr\():
+_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
+ ld r4,_MSR(r1)
+ andi. r0,r4,MSR_PR
+ beq .Lkernel_interrupt_return_\srr
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl interrupt_exit_user_prepare
+ cmpdi r3,0
+ bne- .Lrestore_nvgprs_\srr
+
+.Lfast_user_interrupt_return_\srr:
+BEGIN_FTR_SECTION
+ ld r10,_PPR(r1)
+ mtspr SPRN_PPR,r10
+END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+ .ifc \srr,srr
+ lbz r4,PACASRR_VALID(r13)
+ .else
+ lbz r4,PACAHSRR_VALID(r13)
+ .endif
+ cmpdi r4,0
+ li r4,0
+ bne 1f
+ ld r11,_NIP(r1)
+ ld r12,_MSR(r1)
+ .ifc \srr,srr
+ mtspr SPRN_SRR0,r11
+ mtspr SPRN_SRR1,r12
+1:
+ stb r4,PACASRR_VALID(r13)
+ .else
+ mtspr SPRN_HSRR0,r11
+ mtspr SPRN_HSRR1,r12
+1:
+ stb r4,PACAHSRR_VALID(r13)
+ .endif
+ DEBUG_SRR_VALID \srr
+
+BEGIN_FTR_SECTION
+ stdcx. r0,0,r1 /* to clear the reservation */
+FTR_SECTION_ELSE
+ ldarx r0,0,r1
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
+
+ ld r3,_CCR(r1)
+ ld r4,_LINK(r1)
+ ld r5,_CTR(r1)
+ ld r6,_XER(r1)
+ li r0,0
+
+ REST_4GPRS(7, r1)
+ REST_2GPRS(11, r1)
+ REST_GPR(13, r1)
+
+ mtcr r3
+ mtlr r4
+ mtctr r5
+ mtspr SPRN_XER,r6
+
+ REST_4GPRS(2, r1)
+ REST_GPR(6, r1)
+ REST_GPR(0, r1)
+ REST_GPR(1, r1)
+ .ifc \srr,srr
+ RFI_TO_USER
+ .else
+ HRFI_TO_USER
+ .endif
+ b . /* prevent speculative execution */
+
+.Lrestore_nvgprs_\srr\():
+ REST_NVGPRS(r1)
+ b .Lfast_user_interrupt_return_\srr
+
+ .balign IFETCH_ALIGN_BYTES
+.Lkernel_interrupt_return_\srr\():
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl interrupt_exit_kernel_prepare
+
+.Lfast_kernel_interrupt_return_\srr\():
+ cmpdi cr1,r3,0
+ .ifc \srr,srr
+ lbz r4,PACASRR_VALID(r13)
+ .else
+ lbz r4,PACAHSRR_VALID(r13)
+ .endif
+ cmpdi r4,0
+ li r4,0
+ bne 1f
+ ld r11,_NIP(r1)
+ ld r12,_MSR(r1)
+ .ifc \srr,srr
+ mtspr SPRN_SRR0,r11
+ mtspr SPRN_SRR1,r12
+1:
+ stb r4,PACASRR_VALID(r13)
+ .else
+ mtspr SPRN_HSRR0,r11
+ mtspr SPRN_HSRR1,r12
+1:
+ stb r4,PACAHSRR_VALID(r13)
+ .endif
+ DEBUG_SRR_VALID \srr
+
+BEGIN_FTR_SECTION
+ stdcx. r0,0,r1 /* to clear the reservation */
+FTR_SECTION_ELSE
+ ldarx r0,0,r1
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
+
+ ld r3,_LINK(r1)
+ ld r4,_CTR(r1)
+ ld r5,_XER(r1)
+ ld r6,_CCR(r1)
+ li r0,0
+
+ REST_4GPRS(7, r1)
+ REST_2GPRS(11, r1)
+
+ mtlr r3
+ mtctr r4
+ mtspr SPRN_XER,r5
+
+ /*
+ * Leaving a stale exception_marker on the stack can confuse
+ * the reliable stack unwinder later on. Clear it.
+ */
+ std r0,STACK_FRAME_OVERHEAD-16(r1)
+
+ REST_4GPRS(2, r1)
+
+ bne- cr1,1f /* emulate stack store */
+ mtcr r6
+ REST_GPR(6, r1)
+ REST_GPR(0, r1)
+ REST_GPR(1, r1)
+ .ifc \srr,srr
+ RFI_TO_KERNEL
+ .else
+ HRFI_TO_KERNEL
+ .endif
+ b . /* prevent speculative execution */
+
+1: /*
+ * Emulate stack store with update. New r1 value was already calculated
+ * and updated in our interrupt regs by emulate_loadstore, but we can't
+ * store the previous value of r1 to the stack before re-loading our
+ * registers from it, otherwise they could be clobbered. Use
+ * PACA_EXGEN as temporary storage to hold the store data, as
+ * interrupts are disabled here so it won't be clobbered.
+ */
+ mtcr r6
+ std r9,PACA_EXGEN+0(r13)
+ addi r9,r1,INT_FRAME_SIZE /* get original r1 */
+ REST_GPR(6, r1)
+ REST_GPR(0, r1)
+ REST_GPR(1, r1)
+ std r9,0(r1) /* perform store component of stdu */
+ ld r9,PACA_EXGEN+0(r13)
+
+ .ifc \srr,srr
+ RFI_TO_KERNEL
+ .else
+ HRFI_TO_KERNEL
+ .endif
+ b . /* prevent speculative execution */
+.endm
+
+interrupt_return_macro srr
+interrupt_return_macro hsrr
+
+#endif /* CONFIG_PPC_BOOK3S */
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 6/9] powerpc/64s: save one more register in the masked interrupt handler
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (4 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 5/9] powerpc/64: move interrupt return asm to interrupt_64.S Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 7/9] powerpc/64s: allow alternate return locations for soft-masked interrupts Nicholas Piggin
` (3 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
This frees up one more register (and takes advantage of that to
clean things up a little bit).
This register will be used in the following patch.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 34 ++++++++++++++++------------
1 file changed, 20 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index b370a5f334fc..a01f69e774b5 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2745,7 +2745,6 @@ INT_DEFINE_END(soft_nmi)
* and run it entirely with interrupts hard disabled.
*/
EXC_COMMON_BEGIN(soft_nmi_common)
- mfspr r11,SPRN_SRR0
mr r10,r1
ld r1,PACAEMERGSP(r13)
subi r1,r1,INT_FRAME_SIZE
@@ -2780,19 +2779,24 @@ masked_Hinterrupt:
.else
masked_interrupt:
.endif
- lbz r11,PACAIRQHAPPENED(r13)
- or r11,r11,r10
- stb r11,PACAIRQHAPPENED(r13)
+ stw r9,PACA_EXGEN+EX_CCR(r13)
+ lbz r9,PACAIRQHAPPENED(r13)
+ or r9,r9,r10
+ stb r9,PACAIRQHAPPENED(r13)
+
+ .if ! \hsrr
cmpwi r10,PACA_IRQ_DEC
bne 1f
- lis r10,0x7fff
- ori r10,r10,0xffff
- mtspr SPRN_DEC,r10
+ LOAD_REG_IMMEDIATE(r9, 0x7fffffff)
+ mtspr SPRN_DEC,r9
#ifdef CONFIG_PPC_WATCHDOG
+ lwz r9,PACA_EXGEN+EX_CCR(r13)
b soft_nmi_common
#else
b 2f
#endif
+ .endif
+
1: andi. r10,r10,PACA_IRQ_MUST_HARD_MASK
beq 2f
xori r12,r12,MSR_EE /* clear MSR_EE */
@@ -2801,17 +2805,19 @@ masked_interrupt:
.else
mtspr SPRN_SRR1,r12
.endif
- ori r11,r11,PACA_IRQ_HARD_DIS
- stb r11,PACAIRQHAPPENED(r13)
+ ori r9,r9,PACA_IRQ_HARD_DIS
+ stb r9,PACAIRQHAPPENED(r13)
2: /* done */
- li r10,0
+ li r9,0
.if \hsrr
- stb r10,PACAHSRR_VALID(r13)
+ stb r9,PACAHSRR_VALID(r13)
.else
- stb r10,PACASRR_VALID(r13)
+ stb r9,PACASRR_VALID(r13)
.endif
- ld r10,PACA_EXGEN+EX_CTR(r13)
- mtctr r10
+
+ ld r9,PACA_EXGEN+EX_CTR(r13)
+ mtctr r9
+ lwz r9,PACA_EXGEN+EX_CCR(r13)
mtcrf 0x80,r9
std r1,PACAR1(r13)
ld r9,PACA_EXGEN+EX_R9(r13)
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 7/9] powerpc/64s: allow alternate return locations for soft-masked interrupts
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (5 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 6/9] powerpc/64s: save one more register in the masked interrupt handler Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 8/9] powerpc/64s: interrupt soft-enable race fix Nicholas Piggin
` (2 subsequent siblings)
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
This is a variation of the exception table code which adjusts a failed
page fault return location if it was taken at an address specified in
an exception table, to a corresponding fixup handler address.
This patch adds a similar masked interrupt restart table that is checked
when when an asynchronous interrupt is taken while soft-masked.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/interrupt.h | 18 ++++++++++++++
arch/powerpc/include/asm/ppc_asm.h | 8 +++++++
arch/powerpc/kernel/exceptions-64s.S | 36 +++++++++++++++++++++++++++-
arch/powerpc/kernel/interrupt_64.S | 3 +++
arch/powerpc/kernel/vmlinux.lds.S | 10 ++++++++
arch/powerpc/lib/Makefile | 2 +-
arch/powerpc/lib/restart_table.c | 26 ++++++++++++++++++++
arch/powerpc/perf/core-book3s.c | 19 ++++++++++++---
8 files changed, 117 insertions(+), 5 deletions(-)
create mode 100644 arch/powerpc/lib/restart_table.c
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index 1aeb9a841cc6..5d68c510e5e0 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -18,6 +18,11 @@ static inline void nap_adjust_return(struct pt_regs *regs)
#endif
}
+#ifdef CONFIG_PPC_BOOK3S_64
+extern char __end_soft_masked[];
+unsigned long search_kernel_restart_table(unsigned long addr);
+#endif
+
struct interrupt_state {
#ifdef CONFIG_PPC_BOOK3E_64
enum ctx_state ctx_state;
@@ -47,6 +52,9 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
*/
if (TRAP(regs) != 0x700)
CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ BUG_ON(regs->nip < (unsigned long)__end_soft_masked));
+ if (arch_irq_disabled_regs(regs))
+ BUG_ON(search_kernel_restart_table(regs->nip));
}
#endif
@@ -126,6 +134,8 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte
{
#ifdef CONFIG_PPC64
#ifdef CONFIG_PPC_BOOK3S_64
+ if (!(regs->msr & MSR_PR) && regs->nip < (unsigned long)__end_soft_masked)
+ regs->softe = IRQS_ALL_DISABLED;
state->irq_soft_mask = local_paca->irq_soft_mask;
state->irq_happened = local_paca->irq_happened;
@@ -163,6 +173,14 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter
nap_adjust_return(regs);
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (arch_irq_disabled_regs(regs)) {
+ unsigned long rst = search_kernel_restart_table(regs->nip);
+ if (rst)
+ regs_set_return_ip(regs, rst);
+ }
+#endif
+
#ifdef CONFIG_PPC64
this_cpu_set_ftrace_enabled(state->ftrace_enabled);
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index c1199f6c75a3..da084d695cfe 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -791,6 +791,14 @@ END_FTR_SECTION_NESTED(CPU_FTR_CELL_TB_BUG, CPU_FTR_CELL_TB_BUG, 96)
stringify_in_c(.long (_target) - . ;) \
stringify_in_c(.previous)
+#define RESTART_TABLE(_start, _end, _target) \
+ stringify_in_c(.section __restart_table,"a";)\
+ stringify_in_c(.balign 8;) \
+ stringify_in_c(.llong (_start);) \
+ stringify_in_c(.llong (_end);) \
+ stringify_in_c(.llong (_target);) \
+ stringify_in_c(.previous)
+
#ifdef CONFIG_PPC_FSL_BOOK3E
#define BTB_FLUSH(reg) \
lis reg,BUCSR_INIT@h; \
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index a01f69e774b5..0615c2e724ea 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -514,8 +514,9 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real)
/* Kernel code running below __end_interrupts is implicitly
* soft-masked */
- LOAD_HANDLER(r10, __end_interrupts)
+ LOAD_HANDLER(r10, __end_soft_masked)
cmpld r11,r10
+
li r10,IMASK
blt- 1f
@@ -673,6 +674,28 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
__GEN_COMMON_BODY \name
.endm
+.macro SEARCH_RESTART_TABLE
+ LOAD_REG_IMMEDIATE_SYM(r9, r12, __start___restart_table)
+ LOAD_REG_IMMEDIATE_SYM(r10, r12, __stop___restart_table)
+300:
+ cmpd r9,r10
+ beq 302f
+ ld r12,0(r9)
+ cmpld r11,r12
+ blt 301f
+ ld r12,8(r9)
+ cmpld r11,r12
+ bge 301f
+ ld r12,16(r9)
+ b 303f
+301:
+ addi r9,r9,24
+ b 300b
+302:
+ li r12,0
+303:
+.endm
+
/*
* Restore all registers including H/SRR0/1 saved in a stack frame of a
* standard exception.
@@ -2758,6 +2781,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
mtmsrd r9,1
kuap_restore_amr r9, r10
+
EXCEPTION_RESTORE_REGS hsrr=0
RFI_TO_KERNEL
@@ -2815,6 +2839,16 @@ masked_interrupt:
stb r9,PACASRR_VALID(r13)
.endif
+ SEARCH_RESTART_TABLE
+ cmpdi r12,0
+ beq 3f
+ .if \hsrr
+ mtspr SPRN_HSRR0,r12
+ .else
+ mtspr SPRN_SRR0,r12
+ .endif
+3:
+
ld r9,PACA_EXGEN+EX_CTR(r13)
mtctr r9
lwz r9,PACA_EXGEN+EX_CCR(r13)
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index e121829ef717..9b44f6d3463b 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -605,4 +605,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
interrupt_return_macro srr
interrupt_return_macro hsrr
+ .globl __end_soft_masked
+__end_soft_masked:
+DEFINE_FIXED_SYMBOL(__end_soft_masked)
#endif /* CONFIG_PPC_BOOK3S */
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index e0548b4950de..211c82e96420 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -9,6 +9,14 @@
#define EMITS_PT_NOTE
#define RO_EXCEPTION_TABLE_ALIGN 0
+#define RESTART_TABLE(align) \
+ . = ALIGN(align); \
+ __restart_table : AT(ADDR(__restart_table) - LOAD_OFFSET) { \
+ __start___restart_table = .; \
+ KEEP(*(__restart_table)) \
+ __stop___restart_table = .; \
+ }
+
#include <asm/page.h>
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
@@ -124,6 +132,8 @@ SECTIONS
RO_DATA(PAGE_SIZE)
#ifdef CONFIG_PPC64
+ RESTART_TABLE(8)
+
. = ALIGN(8);
__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
__start___stf_entry_barrier_fixup = .;
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 69a91b571845..5d90bebcf9cf 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -36,7 +36,7 @@ extra-$(CONFIG_PPC64) += crtsavres.o
endif
obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \
- memcpy_power7.o
+ memcpy_power7.o restart_table.o
obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \
memcpy_64.o copy_mc_64.o
diff --git a/arch/powerpc/lib/restart_table.c b/arch/powerpc/lib/restart_table.c
new file mode 100644
index 000000000000..f2df84c46f24
--- /dev/null
+++ b/arch/powerpc/lib/restart_table.c
@@ -0,0 +1,26 @@
+struct restart_table_entry {
+ unsigned long start;
+ unsigned long end;
+ unsigned long fixup;
+};
+
+extern struct restart_table_entry __start___restart_table[];
+extern struct restart_table_entry __stop___restart_table[];
+
+/* Given an address, look for it in the kernel exception table */
+unsigned long search_kernel_restart_table(unsigned long addr)
+{
+ struct restart_table_entry *rte = __start___restart_table;
+
+ while (rte < __stop___restart_table) {
+ unsigned long start = rte->start;
+ unsigned long end = rte->end;
+ unsigned long fixup = rte->fixup;
+
+ if (addr >= start && addr < end)
+ return fixup;
+
+ rte++;
+ }
+ return 0;
+}
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 08643cba1494..4afd292a7a5e 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -332,9 +332,15 @@ static inline void perf_read_regs(struct pt_regs *regs)
* If interrupts were soft-disabled when a PMU interrupt occurs, treat
* it as an NMI.
*/
+extern char __end_soft_masked[];
static inline int perf_intr_is_nmi(struct pt_regs *regs)
{
- return (regs->softe & IRQS_DISABLED);
+ if (regs->softe & IRQS_DISABLED)
+ return true;
+
+ if (!(regs->msr & MSR_PR) && regs->nip < (unsigned long)__end_soft_masked)
+ return true;
+ return false;
}
/*
@@ -2214,6 +2220,8 @@ static bool pmc_overflow(unsigned long val)
return false;
}
+unsigned long search_kernel_restart_table(unsigned long addr);
+
/*
* Performance monitor interrupt stuff
*/
@@ -2301,10 +2309,15 @@ static void __perf_event_interrupt(struct pt_regs *regs)
*/
write_mmcr0(cpuhw, cpuhw->mmcr.mmcr0);
- if (nmi)
+ if (nmi) {
+ unsigned long rst = search_kernel_restart_table(regs->nip);
+ if (rst)
+ regs_set_return_ip(regs, rst);
+
nmi_exit();
- else
+ } else {
irq_exit();
+ }
}
static void perf_event_interrupt(struct pt_regs *regs)
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 8/9] powerpc/64s: interrupt soft-enable race fix
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (6 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 7/9] powerpc/64s: allow alternate return locations for soft-masked interrupts Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 9/9] powerpc/64s: use interrupt restart table to speed up return from interrupt Nicholas Piggin
2020-11-07 10:35 ` [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Christophe Leroy
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
Prevent interrupt restore from allowing racing hard interrupts going
ahead of previous soft-pending ones, by using the soft-masked restart
handler to allow a store to clear the soft-mask while knowing nothing
is soft-pending.
This probably doesn't matter much in practice, but it's a simple
demonstrator / test case to exercise the restart table logic.
XXX: 64e can't do this unless it adds restart table support
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/irq.c | 79 +++++++++++++++++++++++++--------------
1 file changed, 50 insertions(+), 29 deletions(-)
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index c8185f709d26..9671468b2c51 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -317,52 +317,73 @@ notrace void arch_local_irq_restore(unsigned long mask)
unsigned char irq_happened;
/* Write the new soft-enabled value */
- irq_soft_mask_set(mask);
- if (mask)
+ if (mask) {
+ irq_soft_mask_set(mask);
return;
+ }
/*
- * From this point onward, we can take interrupts, preempt,
- * etc... unless we got hard-disabled. We check if an event
- * happened. If none happened, we know we can just return.
- *
- * We may have preempted before the check below, in which case
- * we are checking the "new" CPU instead of the old one. This
- * is only a problem if an event happened on the "old" CPU.
+ * After the stb, interrupts are unmasked and there are no interrupts
+ * pending replay. The restart sequence makes this atomic with
+ * respect to soft-masked interrupts. If this was just a simple code
+ * sequence, a soft-masked interrupt could become pending right after
+ * the comparison and before the stb.
*
- * External interrupt events will have caused interrupts to
- * be hard-disabled, so there is no problem, we
- * cannot have preempted.
+ * This allows interrupts to be unmasked without hard disabling, and
+ * also without new hard interrupts coming in ahead of pending ones.
*/
+ asm_volatile_goto(
+"1: \n"
+" lbz 9,%0(13) \n"
+" cmpwi 9,0 \n"
+" bne %l[happened] \n"
+" stb 9,%1(13) \n"
+"2: \n"
+ RESTART_TABLE(1b, 2b, 1b)
+ : : "i" (offsetof(struct paca_struct, irq_happened)),
+ "i" (offsetof(struct paca_struct, irq_soft_mask))
+ : "cr0", "r9"
+ : happened);
+
+ if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
+ WARN_ON_ONCE(!(mfmsr() & MSR_EE));
+
+ return;
+
+happened:
irq_happened = get_irq_happened();
- if (!irq_happened) {
+ if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
+ WARN_ON_ONCE(!irq_happened);
+
+ if (irq_happened == PACA_IRQ_HARD_DIS) {
if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
- WARN_ON_ONCE(!(mfmsr() & MSR_EE));
+ WARN_ON_ONCE(mfmsr() & MSR_EE);
+ irq_soft_mask_set(IRQS_ENABLED);
+ local_paca->irq_happened = 0;
+ __hard_irq_enable();
return;
}
- /* We need to hard disable to replay. */
+ /* Have interrupts to replay, need to hard disable first */
if (!(irq_happened & PACA_IRQ_HARD_DIS)) {
- if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
- WARN_ON_ONCE(!(mfmsr() & MSR_EE));
+ if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
+ if (!(mfmsr() & MSR_EE)) {
+ /*
+ * An interrupt could have come in and cleared
+ * MSR[EE] and set IRQ_HARD_DIS, so check
+ * IRQ_HARD_DIS again and warn if it is still
+ * clear.
+ */
+ irq_happened = get_irq_happened();
+ WARN_ON_ONCE(!(irq_happened & PACA_IRQ_HARD_DIS));
+ }
+ }
__hard_irq_disable();
} else {
- /*
- * We should already be hard disabled here. We had bugs
- * where that wasn't the case so let's dbl check it and
- * warn if we are wrong. Only do that when IRQ tracing
- * is enabled as mfmsr() can be costly.
- */
if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
if (WARN_ON_ONCE(mfmsr() & MSR_EE))
__hard_irq_disable();
}
-
- if (irq_happened == PACA_IRQ_HARD_DIS) {
- local_paca->irq_happened = 0;
- __hard_irq_enable();
- return;
- }
}
/*
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [RFC PATCH 9/9] powerpc/64s: use interrupt restart table to speed up return from interrupt
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (7 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 8/9] powerpc/64s: interrupt soft-enable race fix Nicholas Piggin
@ 2020-11-06 15:59 ` Nicholas Piggin
2020-11-07 10:35 ` [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Christophe Leroy
9 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-06 15:59 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
The restart table facility is used to return from interrupt without
disabling MSR[EE] or MSR[RI].
Interrupt return code is put into the low soft-masked region, and
critical code that has return SRRs set, soft-masked state set with no
soft-pending interrupts to replay, and no exit work, is put into
alternate return sections. r1 is saved in the paca. If an interrupt hits
at this point, our fixup location re-loads r1 and from there we can get
to regs, critical things are re-loaded, and we go around and do the
exit sequence again.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/asm-prototypes.h | 4 +-
arch/powerpc/include/asm/paca.h | 1 +
arch/powerpc/include/asm/ptrace.h | 13 +-
arch/powerpc/kernel/asm-offsets.c | 3 +
arch/powerpc/kernel/interrupt_64.S | 119 ++++++++++-
arch/powerpc/kernel/syscall_64.c | 242 +++++++++++++---------
6 files changed, 277 insertions(+), 105 deletions(-)
diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h
index 939f3c94c8f3..e0b0fc2913c1 100644
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -71,8 +71,8 @@ void __init machine_init(u64 dt_ptr);
#endif
long system_call_exception(long r3, long r4, long r5, long r6, long r7, long r8, unsigned long r0, struct pt_regs *regs);
notrace unsigned long syscall_exit_prepare(unsigned long r3, struct pt_regs *regs, long scv);
-notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr);
-notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsigned long msr);
+notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs);
+notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs);
long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
u32 len_high, u32 len_low);
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 58e9995c3184..ab123dc85b81 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -167,6 +167,7 @@ struct paca_struct {
u64 kstack; /* Saved Kernel stack addr */
u64 saved_r1; /* r1 save for RTAS calls or PM or EE=0 */
u64 saved_msr; /* MSR saved here by enter_rtas */
+ u64 exit_save_r1; /* Syscall/interrupt R1 save */
#ifdef CONFIG_PPC_BOOK3E
u16 trap_save; /* Used when bad stack is encountered */
#endif
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 2c3e773ce292..cd49769d4194 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -50,14 +50,23 @@ struct pt_regs
union {
struct {
-#ifdef CONFIG_PPC64
+#ifdef CONFIG_PPC_BOOK3S_64
unsigned long ppr;
+ unsigned long exit_result;
#endif
#ifdef CONFIG_PPC_KUAP
unsigned long kuap;
#endif
};
- unsigned long __pad[2]; /* Maintain 16 byte interrupt stack alignment */
+
+ /* Maintain 16 byte interrupt stack alignment */
+#ifdef CONFIG_PPC_KUAP
+#ifdef CONFIG_PPC_BOOK3S_64
+ unsigned long __pad[4];
+#else
+ unsigned long __pad[2];
+#endif
+#endif
};
};
#endif
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index ea13e35dd511..eec4e92bd938 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -290,6 +290,7 @@ int main(void)
OFFSET(ACCOUNT_STARTTIME_USER, paca_struct, accounting.starttime_user);
OFFSET(ACCOUNT_USER_TIME, paca_struct, accounting.utime);
OFFSET(ACCOUNT_SYSTEM_TIME, paca_struct, accounting.stime);
+ OFFSET(PACA_EXIT_SAVE_R1, paca_struct, exit_save_r1);
#ifdef CONFIG_PPC_BOOK3E
OFFSET(PACA_TRAP_SAVE, paca_struct, trap_save);
#endif
@@ -353,7 +354,9 @@ int main(void)
STACK_PT_REGS_OFFSET(_ESR, dsisr);
#else /* CONFIG_PPC64 */
STACK_PT_REGS_OFFSET(SOFTE, softe);
+#ifdef CONFIG_PPC_BOOK3S_64
STACK_PT_REGS_OFFSET(_PPR, ppr);
+#endif
#endif /* CONFIG_PPC64 */
#ifdef CONFIG_PPC_KUAP
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index 9b44f6d3463b..a686d625b8ee 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -113,9 +113,18 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
bl system_call_exception
.Lsyscall_vectored_\name\()_exit:
- addi r4,r1,STACK_FRAME_OVERHEAD
+ addi r4,r1,STACK_FRAME_OVERHEAD
li r5,1 /* scv */
bl syscall_exit_prepare
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+.Lsyscall_vectored_\name\()_rst_start:
+ lbz r11,PACAIRQHAPPENED(r13)
+ andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
+ bne- .Lsyscall_vectored_\name\()_restart
+ li r11,IRQS_ENABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ li r11,0
+ stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
ld r2,_CCR(r1)
ld r4,_NIP(r1)
@@ -165,8 +174,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
b . /* prevent speculative execution */
.Lsyscall_vectored_\name\()_restore_regs:
- li r3,0
- mtmsrd r3,1
mtspr SPRN_SRR0,r4
mtspr SPRN_SRR1,r5
@@ -184,9 +191,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
REST_2GPRS(12, r1)
ld r1,GPR1(r1)
RFI_TO_USER
+.Lsyscall_vectored_\name\()_rst_end:
+
+.Lsyscall_vectored_\name\()_restart:
+ GET_PACA(r13)
+ ld r1,PACA_EXIT_SAVE_R1(r13)
+ ld r2,PACATOC(r13)
+ ld r3,RESULT(r1)
+ addi r4,r1,STACK_FRAME_OVERHEAD
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ bl syscall_exit_restart
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+ b .Lsyscall_vectored_\name\()_rst_start
+
+RESTART_TABLE(.Lsyscall_vectored_\name\()_rst_start, .Lsyscall_vectored_\name\()_rst_end, .Lsyscall_vectored_\name\()_restart)
+
.endm
system_call_vectored common 0x3000
+
/*
* We instantiate another entry copy for the SIGILL variant, with TRAP=0x7ff0
* which is tested by system_call_exception when r0 is -1 (as set by vector
@@ -289,9 +313,18 @@ END_BTB_FLUSH_SECTION
bl system_call_exception
.Lsyscall_exit:
- addi r4,r1,STACK_FRAME_OVERHEAD
+ addi r4,r1,STACK_FRAME_OVERHEAD
li r5,0 /* !scv */
bl syscall_exit_prepare
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+.Lsyscall_rst_start:
+ lbz r11,PACAIRQHAPPENED(r13)
+ andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
+ bne- .Lsyscall_restart
+ li r11,IRQS_ENABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ li r11,0
+ stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
ld r2,_CCR(r1)
ld r6,_LINK(r1)
@@ -356,6 +389,21 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
REST_8GPRS(4, r1)
ld r12,GPR12(r1)
b .Lsyscall_restore_regs_cont
+.Lsyscall_rst_end:
+
+.Lsyscall_restart:
+ GET_PACA(r13)
+ ld r1,PACA_EXIT_SAVE_R1(r13)
+ ld r2,PACATOC(r13)
+ ld r3,RESULT(r1)
+ addi r4,r1,STACK_FRAME_OVERHEAD
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ bl syscall_exit_restart
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+ b .Lsyscall_rst_start
+
+RESTART_TABLE(.Lsyscall_rst_start, .Lsyscall_rst_end, .Lsyscall_restart)
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
.Ltabort_syscall:
@@ -439,16 +487,32 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
ld r4,_MSR(r1)
andi. r0,r4,MSR_PR
beq .Lkernel_interrupt_return_\srr
+.Linterrupt_return_\srr\()_user:
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_user_prepare
cmpdi r3,0
bne- .Lrestore_nvgprs_\srr
+.Lrestore_nvgprs_\srr\()_cont:
+
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+.Linterrupt_return_\srr\()_user_rst_start:
+ lbz r11,PACAIRQHAPPENED(r13)
+ andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
+ bne- .Linterrupt_return_\srr\()_user_restart
+ li r11,IRQS_ENABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ li r11,0
+ stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
.Lfast_user_interrupt_return_\srr:
BEGIN_FTR_SECTION
ld r10,_PPR(r1)
mtspr SPRN_PPR,r10
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+ lbz r4,PACAIRQSOFTMASK(r13)
+ tdnei r4,IRQS_ENABLED
.ifc \srr,srr
lbz r4,PACASRR_VALID(r13)
.else
@@ -503,16 +567,46 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
HRFI_TO_USER
.endif
b . /* prevent speculative execution */
+.Linterrupt_return_\srr\()_user_rst_end:
.Lrestore_nvgprs_\srr\():
REST_NVGPRS(r1)
- b .Lfast_user_interrupt_return_\srr
+ b .Lrestore_nvgprs_\srr\()_cont
+
+.Linterrupt_return_\srr\()_user_restart:
+ GET_PACA(r13)
+ ld r1,PACA_EXIT_SAVE_R1(r13)
+ ld r2,PACATOC(r13)
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ bl interrupt_exit_user_restart
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+ b .Linterrupt_return_\srr\()_user_rst_start
+
+RESTART_TABLE(.Linterrupt_return_\srr\()_user_rst_start, .Linterrupt_return_\srr\()_user_rst_end, .Linterrupt_return_\srr\()_user_restart)
.balign IFETCH_ALIGN_BYTES
.Lkernel_interrupt_return_\srr\():
+.Linterrupt_return_\srr\()_kernel:
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_kernel_prepare
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+.Linterrupt_return_\srr\()_kernel_rst_start:
+ lbz r11,SOFTE(r1)
+ cmpwi r11,IRQS_ENABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ bne 1f
+ lbz r11,PACAIRQHAPPENED(r13)
+ andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
+ bne- .Linterrupt_return_\srr\()_kernel_restart
+ li r11,0
+ stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
+1:
+
.Lfast_kernel_interrupt_return_\srr\():
cmpdi cr1,r3,0
.ifc \srr,srr
@@ -600,6 +694,21 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
HRFI_TO_KERNEL
.endif
b . /* prevent speculative execution */
+.Linterrupt_return_\srr\()_kernel_rst_end:
+
+.Linterrupt_return_\srr\()_kernel_restart:
+ GET_PACA(r13)
+ ld r1,PACA_EXIT_SAVE_R1(r13)
+ ld r2,PACATOC(r13)
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ li r11,IRQS_ALL_DISABLED
+ stb r11,PACAIRQSOFTMASK(r13)
+ bl interrupt_exit_kernel_restart
+ std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
+ b .Linterrupt_return_\srr\()_kernel_rst_start
+
+RESTART_TABLE(.Linterrupt_return_\srr\()_kernel_rst_start, .Linterrupt_return_\srr\()_kernel_rst_end, .Linterrupt_return_\srr\()_kernel_restart)
+
.endm
interrupt_return_macro srr
diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index 672f2a796487..5add073a21b7 100644
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -109,87 +109,27 @@ notrace long system_call_exception(long r3, long r4, long r5,
return f(r3, r4, r5, r6, r7, r8);
}
-/*
- * local irqs must be disabled. Returns false if the caller must re-enable
- * them, check for new work, and try again.
- */
-static notrace inline bool prep_irq_for_enabled_exit(bool clear_ri)
+static notrace inline bool prep_irq_for_enabled_exit(void)
{
/* This must be done with RI=1 because tracing may touch vmaps */
trace_hardirqs_on();
- /* This pattern matches prep_irq_for_idle */
- if (clear_ri)
- __hard_EE_RI_disable();
- else
- __hard_irq_disable();
if (unlikely(lazy_irq_pending_nocheck())) {
- /* Took an interrupt, may have more exit work to do. */
- if (clear_ri)
- __hard_RI_enable();
trace_hardirqs_off();
- local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
-
return false;
}
- local_paca->irq_happened = 0;
- irq_soft_mask_set(IRQS_ENABLED);
return true;
}
-/*
- * This should be called after a syscall returns, with r3 the return value
- * from the syscall. If this function returns non-zero, the system call
- * exit assembly should additionally load all GPR registers and CTR and XER
- * from the interrupt frame.
- *
- * The function graph tracer can not trace the return side of this function,
- * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
- */
-notrace unsigned long syscall_exit_prepare(unsigned long r3,
- struct pt_regs *regs,
- long scv)
+notrace unsigned long syscall_exit_prepare_main(unsigned long r3,
+ struct pt_regs *regs)
{
unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long ti_flags;
unsigned long ret = 0;
- CT_WARN_ON(ct_state() == CONTEXT_USER);
-
- kuap_check_amr();
-
- regs->result = r3;
-
- /* Check whether the syscall is issued inside a restartable sequence */
- rseq_syscall(regs);
-
- ti_flags = *ti_flagsp;
-
- if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && !scv) {
- if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
- r3 = -r3;
- regs->ccr |= 0x10000000; /* Set SO bit in CR */
- }
- }
-
- if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
- if (ti_flags & _TIF_RESTOREALL)
- ret = _TIF_RESTOREALL;
- else
- regs->gpr[3] = r3;
- clear_bits(_TIF_PERSYSCALL_MASK, ti_flagsp);
- } else {
- regs->gpr[3] = r3;
- }
-
- if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
- do_syscall_trace_leave(regs);
- ret |= _TIF_RESTOREALL;
- }
-
again:
- local_irq_disable();
ti_flags = READ_ONCE(*ti_flagsp);
while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
local_irq_enable();
@@ -233,15 +173,16 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
}
}
- user_enter_irqoff();
-
- /* scv need not set RI=0 because SRRs are not used */
- if (unlikely(!prep_irq_for_enabled_exit(!scv))) {
- user_exit_irqoff();
+ if (unlikely(lazy_irq_pending_nocheck())) {
local_irq_enable();
+ local_irq_disable();
goto again;
}
+ trace_hardirqs_on();
+
+ user_enter_irqoff();
+
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
local_paca->tm_scratch = regs->msr;
#endif
@@ -251,17 +192,95 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
return ret;
}
+/*
+ * This should be called after a syscall returns, with r3 the return value
+ * from the syscall. If this function returns non-zero, the system call
+ * exit assembly should additionally load all GPR registers and CTR and XER
+ * from the interrupt frame.
+ *
+ * The function graph tracer can not trace the return side of this function,
+ * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
+ */
+notrace unsigned long syscall_exit_prepare(unsigned long r3,
+ struct pt_regs *regs,
+ long scv)
+{
+ unsigned long *ti_flagsp = ¤t_thread_info()->flags;
+ unsigned long ti_flags;
+ unsigned long ret = 0;
+
+ CT_WARN_ON(ct_state() == CONTEXT_USER);
+
+ kuap_check_amr();
+
+ regs->result = r3;
+
+ /* Check whether the syscall is issued inside a restartable sequence */
+ rseq_syscall(regs);
+
+ ti_flags = *ti_flagsp;
+
+ if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && !scv) {
+ if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
+ r3 = -r3;
+ regs->ccr |= 0x10000000; /* Set SO bit in CR */
+ }
+ }
+
+ if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
+ if (ti_flags & _TIF_RESTOREALL)
+ ret = _TIF_RESTOREALL;
+ else
+ regs->gpr[3] = r3;
+ clear_bits(_TIF_PERSYSCALL_MASK, ti_flagsp);
+ } else {
+ regs->gpr[3] = r3;
+ }
+
+ if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
+ do_syscall_trace_leave(regs);
+ ret |= _TIF_RESTOREALL;
+ }
+
+ local_irq_disable();
+ ret |= syscall_exit_prepare_main(r3, regs);
+
+ regs->exit_result = ret;
+
+ return ret;
+}
+
+notrace unsigned long syscall_exit_restart(unsigned long r3, struct pt_regs *regs)
+{
+ /* This is called in when detecting a soft-pending interrupt as well,
+ * so can't just have restart table returns clear SRR1[MSR] and set
+ * PACA_IRQ_HARD_DIS here (unless the soft-pending case were to clear
+ * MSR[EE] too).
+ */
+ hard_irq_disable();
+
+ trace_hardirqs_off();
+ user_exit_irqoff();
+ account_cpu_user_entry();
+
+ BUG_ON(!user_mode(regs));
+
+ regs->exit_result |= syscall_exit_prepare_main(r3, regs);
+
+ return regs->exit_result;
+}
+
#ifdef CONFIG_PPC_BOOK3S /* BOOK3E not yet using this */
-notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
+notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs)
{
#ifdef CONFIG_PPC_BOOK3E
struct thread_struct *ts = ¤t->thread;
#endif
unsigned long *ti_flagsp = ¤t_thread_info()->flags;
unsigned long ti_flags;
- unsigned long flags;
unsigned long ret = 0;
+ BUG_ON(!irqs_disabled());
if (IS_ENABLED(CONFIG_PPC_BOOK3S))
BUG_ON(!(regs->msr & MSR_RI));
BUG_ON(!(regs->msr & MSR_PR));
@@ -275,8 +294,6 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
*/
kuap_check_amr();
- local_irq_save(flags);
-
again:
ti_flags = READ_ONCE(*ti_flagsp);
while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
@@ -310,14 +327,16 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
}
}
- user_enter_irqoff();
- if (unlikely(!prep_irq_for_enabled_exit(true))) {
- user_exit_irqoff();
+ if (unlikely(lazy_irq_pending_nocheck())) {
local_irq_enable();
local_irq_disable();
goto again;
}
+ trace_hardirqs_on();
+
+ user_enter_irqoff();
+
#ifdef CONFIG_PPC_BOOK3E
if (unlikely(ts->debug.dbcr0 & DBCR0_IDM)) {
/*
@@ -336,19 +355,21 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
account_cpu_user_exit();
+ regs->exit_result = ret;
+
return ret;
}
void unrecoverable_exception(struct pt_regs *regs);
void preempt_schedule_irq(void);
-notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsigned long msr)
+notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
{
unsigned long *ti_flagsp = ¤t_thread_info()->flags;
- unsigned long flags;
unsigned long ret = 0;
unsigned long amr;
+ BUG_ON(!irqs_disabled());
if (IS_ENABLED(CONFIG_PPC_BOOK3S) && unlikely(!(regs->msr & MSR_RI)))
unrecoverable_exception(regs);
BUG_ON(regs->msr & MSR_PR);
@@ -362,13 +383,6 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
amr = kuap_get_and_check_amr();
- if (unlikely(*ti_flagsp & _TIF_EMULATE_STACK_STORE)) {
- clear_bits(_TIF_EMULATE_STACK_STORE, ti_flagsp);
- ret = 1;
- }
-
- local_irq_save(flags);
-
if (regs->softe == IRQS_ENABLED) {
/* Returning to a kernel context with local irqs enabled. */
WARN_ON_ONCE(!(regs->msr & MSR_EE));
@@ -381,27 +395,33 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
}
}
- if (unlikely(!prep_irq_for_enabled_exit(true))) {
- /*
- * Can't local_irq_restore to replay if we were in
- * interrupt context. Must replay directly.
- */
- if (irqs_disabled_flags(flags)) {
- replay_soft_interrupts();
- } else {
- local_irq_restore(flags);
- local_irq_save(flags);
- }
+ if (unlikely(lazy_irq_pending_nocheck())) {
+ hard_irq_disable();
+ replay_soft_interrupts();
/* Took an interrupt, may have more exit work to do. */
goto again;
}
+ local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
+
+ trace_hardirqs_on();
} else {
/* Returning to a kernel context with local irqs disabled. */
- __hard_EE_RI_disable();
if (regs->msr & MSR_EE)
local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
}
+ if (unlikely(*ti_flagsp & _TIF_EMULATE_STACK_STORE)) {
+ /* Stack store can't be restarted (stack might have been clobbered) */
+ __hard_EE_RI_disable();
+ if (unlikely(lazy_irq_pending_nocheck()) && regs->softe == IRQS_ENABLED) {
+ local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
+ __hard_RI_enable();
+ goto again;
+ }
+
+ clear_bits(_TIF_EMULATE_STACK_STORE, ti_flagsp);
+ ret = 1;
+ }
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
local_paca->tm_scratch = regs->msr;
@@ -416,4 +436,34 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
return ret;
}
+
+notrace unsigned long interrupt_exit_user_restart(struct pt_regs *regs)
+{
+ hard_irq_disable();
+
+ trace_hardirqs_off();
+ user_exit_irqoff();
+ account_cpu_user_entry();
+
+ BUG_ON(!user_mode(regs));
+
+ regs->exit_result |= interrupt_exit_user_prepare(regs);
+
+ return regs->exit_result;
+}
+
+notrace unsigned long interrupt_exit_kernel_restart(struct pt_regs *regs)
+{
+ hard_irq_disable();
+
+ set_kuap(AMR_KUAP_BLOCKED);
+
+ if (regs->softe == IRQS_ENABLED)
+ trace_hardirqs_off();
+
+ BUG_ON(user_mode(regs));
+
+ return interrupt_exit_kernel_prepare(regs);
+}
+
#endif
--
2.23.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [RFC PATCH 0/9] powerpc/64s: fast interrupt exit
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
` (8 preceding siblings ...)
2020-11-06 15:59 ` [RFC PATCH 9/9] powerpc/64s: use interrupt restart table to speed up return from interrupt Nicholas Piggin
@ 2020-11-07 10:35 ` Christophe Leroy
2020-11-10 8:49 ` Nicholas Piggin
9 siblings, 1 reply; 14+ messages in thread
From: Christophe Leroy @ 2020-11-07 10:35 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Le 06/11/2020 à 16:59, Nicholas Piggin a écrit :
> This series attempts to improve the speed of interrupts and system calls
> in two major ways.
>
> Firstly, the SRR/HSRR registers do not need to be reloaded if they were
> not used or clobbered fur the duration of the interrupt.
>
> Secondly, an alternate return location facility is added for soft-masked
> asynchronous interrupts and then that's used to set everything up for
> return without having to disable MSR RI or EE.
>
> After this series, the entire system call / interrupt handler fast path
> executes no mtsprs and one mtmsrd to enable interrupts initially, and
> the system call vectored path doesn't even need to do that.
Interesting series.
Unfortunately, can't be done on PPC32 (at least on non bookE), because it would mean mapping kernel
at 0 instead of 0xC0000000. Not sure libc would like it, and anyway it would be an issue for
catching NULL pointer dereferencing, unless we use page tables instead of BATs to map kernel mem,
which would be serious performance cut.
Christophe
>
> Thanks,
> Nick
>
> Nicholas Piggin (9):
> powerpc/64s: syscall real mode entry use mtmsrd rather than rfid
> powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]
> powerpc/64s: introduce different functions to return from SRR vs HSRR
> interrupts
> powerpc/64s: avoid reloading (H)SRR registers if they are still valid
> powerpc/64: move interrupt return asm to interrupt_64.S
> powerpc/64s: save one more register in the masked interrupt handler
> powerpc/64s: allow alternate return locations for soft-masked
> interrupts
> powerpc/64s: interrupt soft-enable race fix
> powerpc/64s: use interrupt restart table to speed up return from
> interrupt
>
> arch/powerpc/Kconfig.debug | 5 +
> arch/powerpc/include/asm/asm-prototypes.h | 4 +-
> arch/powerpc/include/asm/head-64.h | 2 +-
> arch/powerpc/include/asm/interrupt.h | 18 +
> arch/powerpc/include/asm/paca.h | 3 +
> arch/powerpc/include/asm/ppc_asm.h | 8 +
> arch/powerpc/include/asm/ptrace.h | 28 +-
> arch/powerpc/kernel/asm-offsets.c | 5 +
> arch/powerpc/kernel/entry_64.S | 508 ---------------
> arch/powerpc/kernel/exceptions-64s.S | 180 ++++--
> arch/powerpc/kernel/fpu.S | 2 +
> arch/powerpc/kernel/head_64.S | 5 +-
> arch/powerpc/kernel/interrupt_64.S | 720 +++++++++++++++++++++
> arch/powerpc/kernel/irq.c | 79 ++-
> arch/powerpc/kernel/kgdb.c | 2 +-
> arch/powerpc/kernel/kprobes-ftrace.c | 2 +-
> arch/powerpc/kernel/kprobes.c | 10 +-
> arch/powerpc/kernel/process.c | 21 +-
> arch/powerpc/kernel/rtas.c | 13 +-
> arch/powerpc/kernel/signal.c | 2 +-
> arch/powerpc/kernel/signal_64.c | 14 +
> arch/powerpc/kernel/syscall_64.c | 242 ++++---
> arch/powerpc/kernel/syscalls.c | 2 +
> arch/powerpc/kernel/traps.c | 18 +-
> arch/powerpc/kernel/vector.S | 6 +-
> arch/powerpc/kernel/vmlinux.lds.S | 10 +
> arch/powerpc/lib/Makefile | 2 +-
> arch/powerpc/lib/restart_table.c | 26 +
> arch/powerpc/lib/sstep.c | 5 +-
> arch/powerpc/math-emu/math.c | 2 +-
> arch/powerpc/mm/fault.c | 2 +-
> arch/powerpc/perf/core-book3s.c | 19 +-
> arch/powerpc/platforms/powernv/opal-call.c | 3 +
> arch/powerpc/sysdev/fsl_pci.c | 2 +-
> 34 files changed, 1244 insertions(+), 726 deletions(-)
> create mode 100644 arch/powerpc/kernel/interrupt_64.S
> create mode 100644 arch/powerpc/lib/restart_table.c
>
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC PATCH 0/9] powerpc/64s: fast interrupt exit
2020-11-07 10:35 ` [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Christophe Leroy
@ 2020-11-10 8:49 ` Nicholas Piggin
2020-11-10 11:31 ` Christophe Leroy
0 siblings, 1 reply; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-10 8:49 UTC (permalink / raw)
To: Christophe Leroy, linuxppc-dev
Excerpts from Christophe Leroy's message of November 7, 2020 8:35 pm:
>
>
> Le 06/11/2020 à 16:59, Nicholas Piggin a écrit :
>> This series attempts to improve the speed of interrupts and system calls
>> in two major ways.
>>
>> Firstly, the SRR/HSRR registers do not need to be reloaded if they were
>> not used or clobbered fur the duration of the interrupt.
>>
>> Secondly, an alternate return location facility is added for soft-masked
>> asynchronous interrupts and then that's used to set everything up for
>> return without having to disable MSR RI or EE.
>>
>> After this series, the entire system call / interrupt handler fast path
>> executes no mtsprs and one mtmsrd to enable interrupts initially, and
>> the system call vectored path doesn't even need to do that.
>
> Interesting series.
>
> Unfortunately, can't be done on PPC32 (at least on non bookE), because it would mean mapping kernel
> at 0 instead of 0xC0000000. Not sure libc would like it, and anyway it would be an issue for
> catching NULL pointer dereferencing, unless we use page tables instead of BATs to map kernel mem,
> which would be serious performance cut.
Hmm, why would you have to map at 0?
PPC32 doesn't have soft mask interrupts, but you could still test all
MSR[PR]=0 interrupts to see if they land inside some region to see if
they hit in the restart table I think?
Could PPC32 skip the SRR reload at least? That's simpler.
Thanks,
Nick
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC PATCH 0/9] powerpc/64s: fast interrupt exit
2020-11-10 8:49 ` Nicholas Piggin
@ 2020-11-10 11:31 ` Christophe Leroy
2020-11-11 4:49 ` Nicholas Piggin
0 siblings, 1 reply; 14+ messages in thread
From: Christophe Leroy @ 2020-11-10 11:31 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Le 10/11/2020 à 09:49, Nicholas Piggin a écrit :
> Excerpts from Christophe Leroy's message of November 7, 2020 8:35 pm:
>>
>>
>> Le 06/11/2020 à 16:59, Nicholas Piggin a écrit :
>>> This series attempts to improve the speed of interrupts and system calls
>>> in two major ways.
>>>
>>> Firstly, the SRR/HSRR registers do not need to be reloaded if they were
>>> not used or clobbered fur the duration of the interrupt.
>>>
>>> Secondly, an alternate return location facility is added for soft-masked
>>> asynchronous interrupts and then that's used to set everything up for
>>> return without having to disable MSR RI or EE.
>>>
>>> After this series, the entire system call / interrupt handler fast path
>>> executes no mtsprs and one mtmsrd to enable interrupts initially, and
>>> the system call vectored path doesn't even need to do that.
>>
>> Interesting series.
>>
>> Unfortunately, can't be done on PPC32 (at least on non bookE), because it would mean mapping kernel
>> at 0 instead of 0xC0000000. Not sure libc would like it, and anyway it would be an issue for
>> catching NULL pointer dereferencing, unless we use page tables instead of BATs to map kernel mem,
>> which would be serious performance cut.
>
> Hmm, why would you have to map at 0?
In real mode, physical mem is at 0. If we want to switch from real to virtual mode by just writing
to MSR, then we need virtuel addresses match with real addresses ?
We could play with chip selects to put RAM at 0xc0000000, but then we'd have a problem with
exception as they have to be at 0. Or we could play with MSR[IP] and get the exceptions at
0xfff00000, but that would not be so easy I guess.
>
> PPC32 doesn't have soft mask interrupts, but you could still test all
> MSR[PR]=0 interrupts to see if they land inside some region to see if
> they hit in the restart table I think?
Yes and this is already what is done at exit for the ones that handle MSR[RI] I think.
>
> Could PPC32 skip the SRR reload at least? That's simpler.
I think that would only be possible if real addresses where matching virtual addresses, or am I
missing something ?
Christophe
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [RFC PATCH 0/9] powerpc/64s: fast interrupt exit
2020-11-10 11:31 ` Christophe Leroy
@ 2020-11-11 4:49 ` Nicholas Piggin
0 siblings, 0 replies; 14+ messages in thread
From: Nicholas Piggin @ 2020-11-11 4:49 UTC (permalink / raw)
To: Christophe Leroy, linuxppc-dev
Excerpts from Christophe Leroy's message of November 10, 2020 9:31 pm:
>
>
> Le 10/11/2020 à 09:49, Nicholas Piggin a écrit :
>> Excerpts from Christophe Leroy's message of November 7, 2020 8:35 pm:
>>>
>>>
>>> Le 06/11/2020 à 16:59, Nicholas Piggin a écrit :
>>>> This series attempts to improve the speed of interrupts and system calls
>>>> in two major ways.
>>>>
>>>> Firstly, the SRR/HSRR registers do not need to be reloaded if they were
>>>> not used or clobbered fur the duration of the interrupt.
>>>>
>>>> Secondly, an alternate return location facility is added for soft-masked
>>>> asynchronous interrupts and then that's used to set everything up for
>>>> return without having to disable MSR RI or EE.
>>>>
>>>> After this series, the entire system call / interrupt handler fast path
>>>> executes no mtsprs and one mtmsrd to enable interrupts initially, and
>>>> the system call vectored path doesn't even need to do that.
>>>
>>> Interesting series.
>>>
>>> Unfortunately, can't be done on PPC32 (at least on non bookE), because it would mean mapping kernel
>>> at 0 instead of 0xC0000000. Not sure libc would like it, and anyway it would be an issue for
>>> catching NULL pointer dereferencing, unless we use page tables instead of BATs to map kernel mem,
>>> which would be serious performance cut.
>>
>> Hmm, why would you have to map at 0?
>
> In real mode, physical mem is at 0. If we want to switch from real to virtual mode by just writing
> to MSR, then we need virtuel addresses match with real addresses ?
Ah that's what I missed.
64s real mode masks out the top 2 bits of the address which is how that
works. But I don't usually think about that path anyway because most
iterrupts arrive with MMU on.
> We could play with chip selects to put RAM at 0xc0000000, but then we'd have a problem with
> exception as they have to be at 0. Or we could play with MSR[IP] and get the exceptions at
> 0xfff00000, but that would not be so easy I guess.
>
>>
>> PPC32 doesn't have soft mask interrupts, but you could still test all
>> MSR[PR]=0 interrupts to see if they land inside some region to see if
>> they hit in the restart table I think?
>
> Yes and this is already what is done at exit for the ones that handle MSR[RI] I think.
Interesting, I'll have to check that out.
>>
>> Could PPC32 skip the SRR reload at least? That's simpler.
>
> I think that would only be possible if real addresses where matching virtual addresses, or am I
> missing something ?
No you're right, I was missing something.
Thanks,
Nick
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2020-11-11 4:53 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-06 15:59 [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 1/9] powerpc/64s: syscall real mode entry use mtmsrd rather than rfid Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 2/9] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE] Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 3/9] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 4/9] powerpc/64s: avoid reloading (H)SRR registers if they are still valid Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 5/9] powerpc/64: move interrupt return asm to interrupt_64.S Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 6/9] powerpc/64s: save one more register in the masked interrupt handler Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 7/9] powerpc/64s: allow alternate return locations for soft-masked interrupts Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 8/9] powerpc/64s: interrupt soft-enable race fix Nicholas Piggin
2020-11-06 15:59 ` [RFC PATCH 9/9] powerpc/64s: use interrupt restart table to speed up return from interrupt Nicholas Piggin
2020-11-07 10:35 ` [RFC PATCH 0/9] powerpc/64s: fast interrupt exit Christophe Leroy
2020-11-10 8:49 ` Nicholas Piggin
2020-11-10 11:31 ` Christophe Leroy
2020-11-11 4:49 ` Nicholas Piggin
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