linux-kernel - [GIT pull] x86/pti for 5.4-rc1

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Date:   Mon, 16 Sep 2019 13:30:20 -0000
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] x86/pti for 5.4-rc1

Linus,

please pull the latest x86-pti-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-pti-for-linus

up to:  990784b57731: x86/mm/pti: Do not invoke PTI functions when PTI is disabled

Two small PTI updates:

  - Handle unaligned addresses gracefully in pti_clone_pagetable(). Not an
    issue with current callers, but a correctness problem. Adds a warning
    so any caller which hands in an unaligned address gets pointed out
    clearly.

  - Prevent PTI functions from being invoked when PTI is disabled at
    boottime. While this does not cause any harm today, it's pointless code
    executed and prone to cause subtle issues if the PTI implementation
    changes internally over time.

Thanks,

	tglx

------------------>
Song Liu (1):
      x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable()

Thomas Gleixner (1):
      x86/mm/pti: Do not invoke PTI functions when PTI is disabled


 arch/x86/mm/pti.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index b196524759ec..7f2140414440 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
 
 		pud = pud_offset(p4d, addr);
 		if (pud_none(*pud)) {
-			addr += PUD_SIZE;
+			WARN_ON_ONCE(addr & ~PUD_MASK);
+			addr = round_up(addr + 1, PUD_SIZE);
 			continue;
 		}
 
 		pmd = pmd_offset(pud, addr);
 		if (pmd_none(*pmd)) {
-			addr += PMD_SIZE;
+			WARN_ON_ONCE(addr & ~PMD_MASK);
+			addr = round_up(addr + 1, PMD_SIZE);
 			continue;
 		}
 
@@ -666,6 +668,8 @@ void __init pti_init(void)
  */
 void pti_finalize(void)
 {
+	if (!boot_cpu_has(X86_FEATURE_PTI))
+		return;
 	/*
 	 * We need to clone everything (again) that maps parts of the
 	 * kernel image.