From: Khalid Aziz <khalid.aziz@oracle.com>
Date: Fri, 2 Dec 2016 19:45:37 +0000 (-0700)
Subject: sparc64: Add sensible read values for /proc/<pid>/sparc_adi
X-Git-Tag: v4.1.12-92~1^2~1
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=54cc45869238af877fc71e7700dc5b90fc33fc22;p=users%2Fjedix%2Flinux-maple.git

sparc64: Add sensible read values for /proc/<pid>/sparc_adi

This patch makes value read from /proc/<pid>/sparc_adi consistent
across platforms that support ADi and ones that do not. When ADI is
not available for a process either due to process being an anonymous
process on an ADI-capable platform or the process is running on a
non-ADI platform, a read from /proc/<pid>/sparc_adi always reads a
value of -1. This patch updates the documentation file as well with
the values for sparc_adi proc file.

Orabug: 25173120

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>
---

diff --git a/Documentation/sparc/adi.txt b/Documentation/sparc/adi.txt
index 1740f8ac3f2cb..2f25edcf2906c 100644
--- a/Documentation/sparc/adi.txt
+++ b/Documentation/sparc/adi.txt
@@ -148,6 +148,25 @@ MCD disabled
 		siginfo.si_trapno = 0;
 
 
+ADI specific proc files
+-----------------------
+
+ADI feature adds two new proc files:
+
+/proc/sys/kernel/mcd_on_by_default
+	This file indicates if TTE.mcd (and hence ADI) will be enabled by
+	default for a new task. Reading from the file returns current value
+	which can be changed by writing to this file.
+
+/proc/<pid>/sparc_adi
+	This file reports the current state of ADI for the process. A
+	value of 1 means ADI si enabled currently for the process, a
+	value of 0 means ADI is not enabled currently for the process,
+	and a value of -1 means ADI is not available to the process.
+	Writing to this file, when ADI is available, changes the current
+	state of ADI for theprocess.
+
+
 Sample program to use ADI
 -------------------------
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 47f05bf4e7dc3..867206e142318 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1309,21 +1309,22 @@ sparc_adi_show(struct seq_file *m, void *v)
 	if (!task)
 		return -ENOENT;
 
-	if (!adi_capable())
-		return -ENOTSUPP;
-
-	task_lock(task);
-
-	/* anonymous processes can not use ADI */
-	if (task->mm) {
-		struct pt_regs *regs;
-		regs = task_pt_regs(task);
-		seq_printf(m, "%d\n", !!(regs->tstate & TSTATE_MCDE));
-	} else
+	if (!adi_capable()) {
 		seq_printf(m, "-1\n");
+	} else {
+		task_lock(task);
 
-	task_unlock(task);
-	put_task_struct(task);
+		/* anonymous processes can not use ADI */
+		if (task->mm) {
+			struct pt_regs *regs;
+			regs = task_pt_regs(task);
+			seq_printf(m, "%d\n", !!(regs->tstate & TSTATE_MCDE));
+		} else
+			seq_printf(m, "-1\n");
+
+		task_unlock(task);
+		put_task_struct(task);
+	}
 	return 0;
 }