linux-kernel - [REVIEW][PATCH 3/9] signal/powerpc: Call _exception_pkey directly from bad_key_fault

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Date:   Tue, 18 Sep 2018 19:58:44 +0200
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [REVIEW][PATCH 3/9] signal/powerpc: Call _exception_pkey directly from bad_key_fault_exception

This removes the need for other code paths to deal with pkey exceptions.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 arch/powerpc/mm/fault.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index e5725fa96a48..5afc1ee55043 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -145,7 +145,17 @@ static noinline int bad_area(struct pt_regs *regs, unsigned long address)
 static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address,
 				    int pkey)
 {
-	return __bad_area_nosemaphore(regs, address, SEGV_PKUERR, pkey);
+	/*
+	 * If we are in kernel mode, bail out with a SEGV, this will
+	 * be caught by the assembly which will restore the non-volatile
+	 * registers before calling bad_page_fault()
+	 */
+	if (!user_mode(regs))
+		return SIGSEGV;
+
+	_exception_pkey(SIGSEGV, regs, SEGV_PKUERR, address, pkey);
+
+	return 0;
 }
 
 static noinline int bad_access(struct pt_regs *regs, unsigned long address)
-- 
2.17.1