linux-kernel - [PATCH 4.18 145/150] sparc64: Set %l4 properly on trap return after handling signals.

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Date:   Fri,  2 Nov 2018 19:35:07 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.18 145/150] sparc64: Set %l4 properly on trap return after handling signals.

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "David S. Miller" <davem@...emloft.net>

[ Upstream commit d1f1f98c6d1708a90436e1a3b2aff5e93946731b ]

If we did some signal processing, we have to reload the pt_regs
tstate register because it's value may have changed.

In doing so we also have to extract the %pil value contained in there
anre load that into %l4.

This value is at bit 20 and thus needs to be shifted down before we
later write it into the %pil register.

Most of the time this is harmless as we are returning to userspace
and the %pil is zero for that case.

Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/sparc/kernel/rtrap_64.S |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/sparc/kernel/rtrap_64.S
+++ b/arch/sparc/kernel/rtrap_64.S
@@ -85,8 +85,9 @@ __handle_signal:
 		ldx			[%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
 		sethi			%hi(0xf << 20), %l4
 		and			%l1, %l4, %l4
+		andn			%l1, %l4, %l1
 		ba,pt			%xcc, __handle_preemption_continue
-		 andn			%l1, %l4, %l1
+		 srl			%l4, 20, %l4

 		/* When returning from a NMI (%pil==15) interrupt we want to
 		 * avoid running softirqs, doing IRQ tracing, preempting, etc.