[tip: timers/vdso] powerpc: Add kconfig option for the systemcfg page

["tip-bot2 for Thomas Weißschuh" <tip-bot2@linutronix.de>]

The following commit has been merged into the timers/vdso branch of tip:

Commit-ID:     c22c06b4cc3a7434f36dac9310604be3ebc6f4f9
Gitweb:        https://git.kernel.org/tip/c22c06b4cc3a7434f36dac9310604be3ebc6f4f9
Author:        Thomas Weißschuh <thomas.weissschuh@linutronix.de>
AuthorDate:    Thu, 10 Oct 2024 09:01:27 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 02 Nov 2024 12:37:35 +01:00

powerpc: Add kconfig option for the systemcfg page

The systemcfg page through procfs is only a backwards-compatible
interface for very old applications.
Make it possible to be disabled.

This also creates a convenient config #define to guard any accesses to
the systemcfg page.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241010-vdso-generic-base-v1-25-b64f0842d512@linutronix.de

---
 arch/powerpc/Kconfig               | 8 ++++++++
 arch/powerpc/kernel/proc_powerpc.c | 4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8094a01..5d348e1 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1298,6 +1298,14 @@ config MODULES_SIZE
 
 endmenu
 
+config PPC64_PROC_SYSTEMCFG
+	def_bool y
+	depends on PPC64 && PROC_FS
+	help
+	  This option enables the presence of /proc/ppc64/systemcfg through
+	  which the systemcfg page can be accessed.
+	  This interface only exists for backwards-compatibility.
+
 if PPC64
 # This value must have zeroes in the bottom 60 bits otherwise lots will break
 config PAGE_OFFSET
diff --git a/arch/powerpc/kernel/proc_powerpc.c b/arch/powerpc/kernel/proc_powerpc.c
index 910d208..3bda365 100644
--- a/arch/powerpc/kernel/proc_powerpc.c
+++ b/arch/powerpc/kernel/proc_powerpc.c
@@ -14,7 +14,7 @@
 #include <asm/rtas.h>
 #include <linux/uaccess.h>
 
-#ifdef CONFIG_PPC64
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
 
 static loff_t page_map_seek(struct file *file, loff_t off, int whence)
 {
@@ -59,7 +59,7 @@ static int __init proc_ppc64_init(void)
 }
 __initcall(proc_ppc64_init);
 
-#endif /* CONFIG_PPC64 */
+#endif /* CONFIG_PPC64_PROC_SYSTEMCFG */
 
 /*
  * Create the ppc64 and ppc64/rtas directories early. This allows us to