linux-kernel - [PATCH RFC 6/8] powerpc/64: barrier

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Date:   Tue, 13 Mar 2018 19:33:04 +0100
From:   Michal Suchanek <msuchanek@...e.de>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Suchanek <msuchanek@...e.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Nicholas Piggin <npiggin@...il.com>,
        "Tobin C. Harding" <me@...in.cc>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        David Gibson <david@...son.dropbear.id.au>,
        Al Viro <viro@...iv.linux.org.uk>,
        Michael Neuling <mikey@...ling.org>,
        "Oliver O'Halloran" <oohall@...il.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Balbir Singh <bsingharora@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Daniel Axtens <dja@...ens.net>,
        Russell Currey <ruscur@...sell.cc>,
        Joe Perches <joe@...ches.com>,
        "Bryant G. Ly" <bryantly@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH RFC 6/8] powerpc/64: barrier_nospec: Add debugfs trigger

Copypasta from rfi implementation

Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
 arch/powerpc/kernel/setup_64.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index d1d9f047161e..4b67b7b877d9 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -955,6 +955,41 @@ static __init int rfi_flush_debugfs_init(void)
 	return 0;
 }
 device_initcall(rfi_flush_debugfs_init);
+
+static int barrier_nospec_set(void *data, u64 val)
+{
+	switch (val) {
+	case 0:
+	case 1:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (!!val == !!barrier_nospec_enabled)
+		return 0;
+
+	barrier_nospec_enable(!!val);
+
+	return 0;
+}
+
+static int barrier_nospec_get(void *data, u64 *val)
+{
+	*val = barrier_nospec_enabled ? 1 : 0;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_barrier_nospec,
+			barrier_nospec_get, barrier_nospec_set, "%llu\n");
+
+static __init int barrier_nospec_debugfs_init(void)
+{
+	debugfs_create_file("barrier_nospec", 0600, powerpc_debugfs_root, NULL,
+			    &fops_barrier_nospec);
+	return 0;
+}
+device_initcall(barrier_nospec_debugfs_init);
 #endif
 
 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
-- 
2.13.6