Commit 2384b36f authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc: Select ARCH_HAS_MEMBARRIER_SYNC_CORE 



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

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200716013522.338318-1-npiggin@gmail.com
parent 147c1341

Documentation/features/sched/membarrier-sync-core/arch-support.txt

+2 −2
Original line number Diff line number Diff line
@@ -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 |

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/include/asm/exception-64e.h

+5 −1
Original line number Diff line number Diff line
@@ -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

arch/powerpc/include/asm/exception-64s.h

+8 −0
Original line number Diff line number Diff line
@@ -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;					\

arch/powerpc/kernel/entry_32.S

+6 −0
Original line number Diff line number Diff line
@@ -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

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