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commit e627106266ad8785457fadbf5bf67ed604d2a353
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Mon May 11 11:20:02 2020 +0200
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POWER: Add context-synchronizing instructions to pkey_write [BZ #25954]
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Sandipan Das reported that,
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"The Power ISA mandates that all writes to the Authority
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Mask Register (AMR) must always be preceded as well as
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succeeded by a context-synchronizing instruction. This
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applies to both the privileged and unprivileged variants
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of the Move To AMR instruction.
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This [requirement] is from Table 6 of Chapter 11 in page 1134 of Power
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ISA 3.0B. The document can be found here:
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<https://ibm.ent.box.com/s/1hzcwkwf8rbju5h9iyf44wm94amnlcrv>
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"
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See this kernel patch submission:
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<https://lore.kernel.org/linuxppc-dev/5f65cf37be993760de8112a88da194e3ccbb2bf8.1588959697.git.sandipan@linux.ibm.com/>
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diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h b/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h
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index 623b073d5a585d51..25d080c9a6f30942 100644
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--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h
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+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h
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@@ -37,7 +37,7 @@ pkey_read (void)
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static inline void
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pkey_write (unsigned long int value)
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{
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- __asm__ volatile ("mtspr 13, %0" : : "r" (value));
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+ __asm__ volatile ("isync; mtspr 13, %0; isync" : : "r" (value));
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}
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/* Number of the largest supported key. This depends on the width of
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