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powerpc: Select ARCH_HAS_MEMBARRIER_SYNC_CORE

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powerpc return from interrupt and return from system call sequences
are context synchronising.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200716013522.338318-1-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2020-07-16 11:35:22 +10:00 committed by Michael Ellerman
parent 147c13413c
commit 2384b36f91
5 changed files with 22 additions and 3 deletions
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4
Documentation/features/sched/membarrier-sync-core/arch-support.txt
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@ -5,7 +5,7 @@
#
# Architecture requirements
#
# * arm/arm64
# * arm/arm64/powerpc
#
# Rely on implicit context synchronization as a result of exception return
# when returning from IPI handler, and when returning to user-space.
@ -45,7 +45,7 @@
| nios2: | TODO |
| openrisc: | TODO |
| parisc: | TODO |
| powerpc: | TODO |
| powerpc: | ok |
| riscv: | TODO |
| s390: | TODO |
| sh: | TODO |

1
arch/powerpc/Kconfig
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@ -131,6 +131,7 @@ config PPC
select ARCH_HAS_PTE_DEVMAP if PPC_BOOK3S_64
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_MEMBARRIER_CALLBACKS
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
select ARCH_HAS_STRICT_KERNEL_RWX if (PPC32 && !HIBERNATION)
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

6
arch/powerpc/include/asm/exception-64e.h
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@ -204,7 +204,11 @@ exc_##label##_book3e:
LOAD_REG_ADDR(r3,interrupt_base_book3e);\
ori r3,r3,vector_offset@l; \
mtspr SPRN_IVOR##vector_number,r3;
/*
* powerpc relies on return from interrupt/syscall being context synchronising
* (which rfi is) to support ARCH_HAS_MEMBARRIER_SYNC_CORE without additional
* synchronisation instructions.
*/
#define RFI_TO_KERNEL \
rfi

8
arch/powerpc/include/asm/exception-64s.h
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@ -68,6 +68,14 @@
*
* The nop instructions allow us to insert one or more instructions to flush the
* L1-D cache when returning to userspace or a guest.
*
* powerpc relies on return from interrupt/syscall being context synchronising
* (which hrfid, rfid, and rfscv are) to support ARCH_HAS_MEMBARRIER_SYNC_CORE
* without additional synchronisation instructions.
*
* soft-masked interrupt replay does not include a context-synchronising rfid,
* but those always return to kernel, the sync is only required when returning
* to user.
*/
#define RFI_FLUSH_SLOT \
RFI_FLUSH_FIXUP_SECTION; \

6
arch/powerpc/kernel/entry_32.S
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@ -35,6 +35,12 @@
#include "head_32.h"
/*
* powerpc relies on return from interrupt/syscall being context synchronising
* (which rfi is) to support ARCH_HAS_MEMBARRIER_SYNC_CORE without additional
* synchronisation instructions.
*/
/*
* Align to 4k in order to ensure that all functions modyfing srr0/srr1
* fit into one page in order to not encounter a TLB miss between the