linux-kernel - [PATCH 4.14 249/293] powerpc/xmon: Fix disabling tracing while in xmon

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Message-Id: <20190729190843.523886551@linuxfoundation.org>
Date:   Mon, 29 Jul 2019 21:22:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 249/293] powerpc/xmon: Fix disabling tracing while in xmon

[ Upstream commit aaf06665f7ea3ee9f9754e16c1a507a89f1de5b1 ]

Commit ed49f7fd6438d ("powerpc/xmon: Disable tracing when entering
xmon") added code to disable recording trace entries while in xmon. The
commit introduced a variable 'tracing_enabled' to record if tracing was
enabled on xmon entry, and used this to conditionally enable tracing
during exit from xmon.

However, we are not checking the value of 'fromipi' variable in
xmon_core() when setting 'tracing_enabled'. Due to this, when secondary
cpus enter xmon, they will see tracing as being disabled already and
tracing won't be re-enabled on exit. Fix the same.

Fixes: ed49f7fd6438d ("powerpc/xmon: Disable tracing when entering xmon")
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/xmon/xmon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index f752f771f29d..6b9038a3e79f 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -465,8 +465,10 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
 	local_irq_save(flags);
 	hard_irq_disable();
 
-	tracing_enabled = tracing_is_on();
-	tracing_off();
+	if (!fromipi) {
+		tracing_enabled = tracing_is_on();
+		tracing_off();
+	}
 
 	bp = in_breakpoint_table(regs->nip, &offset);
 	if (bp != NULL) {
-- 
2.20.1