linux-kernel - [REVIEW][PATCH 16/20] signal/x86: Pass pkey not vma into __bad

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Date:   Tue, 18 Sep 2018 02:05:42 +0200
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [REVIEW][PATCH 16/20] signal/x86: Pass pkey not vma into __bad_area

There is only one caller of __bad_area that passes in PKUERR and thus
will generate a siginfo with si_pkey set.  Therefore simplify the
logic and hoist reading of vma_pkey up into that caller, and just
pass *pkey into __bad_area.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 arch/x86/mm/fault.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index f82106578364..11a93f14a674 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -904,22 +904,16 @@ bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
 
 static void
 __bad_area(struct pt_regs *regs, unsigned long error_code,
-	   unsigned long address,  struct vm_area_struct *vma, int si_code)
+	   unsigned long address, u32 *pkey, int si_code)
 {
 	struct mm_struct *mm = current->mm;
-	u32 pkey;
-
-	if (vma)
-		pkey = vma_pkey(vma);
-
 	/*
 	 * Something tried to access memory that isn't in our memory map..
 	 * Fix it, but check if it's kernel or user first..
 	 */
 	up_read(&mm->mmap_sem);
 
-	__bad_area_nosemaphore(regs, error_code, address,
-			       (vma) ? &pkey : NULL, si_code);
+	__bad_area_nosemaphore(regs, error_code, address, pkey, si_code);
 }
 
 static noinline void
@@ -954,10 +948,12 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
 	 * But, doing it this way allows compiler optimizations
 	 * if pkeys are compiled out.
 	 */
-	if (bad_area_access_from_pkeys(error_code, vma))
-		__bad_area(regs, error_code, address, vma, SEGV_PKUERR);
+	if (bad_area_access_from_pkeys(error_code, vma)) {
+		u32 pkey = vma_pkey(vma);
+		__bad_area(regs, error_code, address, &pkey, SEGV_PKUERR);
+	}
 	else
-		__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
+		__bad_area(regs, error_code, address, NULL, SEGV_ACCERR);
 }
 
 static void
-- 
2.17.1