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PR/54257 CVS commit: src/sys/arch/x86/x86

The following reply was made to PR port-amd64/54257; it has been noted by GNATS.

From: "Maxime Villard" <>
Subject: PR/54257 CVS commit: src/sys/arch/x86/x86
Date: Sat, 1 Jun 2019 08:12:26 +0000

 Module Name:	src
 Committed By:	maxv
 Date:		Sat Jun  1 08:12:26 UTC 2019
 Modified Files:
 	src/sys/arch/x86/x86: pmap.c
 Log Message:
 Fix two bugs in pmap_write_protect():
  * The mask should be ~PAGE_MASK, not PTE_FRAME. PTE_FRAME eliminates the
    higher bits, and that's not wanted.
  * The computation of tva is incorrect: if the VA is in kernel space we
    must take the canonical hole into account, and here we were not.
 We've had these bugs basically forever. It meant that uvm_km_protect()
 would never flush the correct VA, and a stale TLB entry would persist.
 Fixes PR/54257. Since I added PCID support we execute invpcid in invlpg(),
 and invpcid triggers a #GP if the address is non canonical, contrary to
 invlpg. The wrong computation of the VA during a modload happened to hit
 the canonical hole.
 To generate a diff of this commit:
 cvs rdiff -u -r1.333 -r1.334 src/sys/arch/x86/x86/pmap.c
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

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