powerpc: add link stack flush mitigation status in debugfs.

The link stack flush status is not visible in debugfs. It can be enabled
even when count cache flush is disabled. Add separate file for its
status.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
[mpe: Update for change to link_stack_flush_type]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191127220959.6208-1-msuchanek@suse.de

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index e159d4093d98258948d11de88e6db5bead422465..d96fd14bd7c9c614036f758b466502bb4d84b0aa 100644 (file)
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -747,14 +747,29 @@ static int count_cache_flush_get(void *data, u64 *val)
        return 0;
 }
 
+static int link_stack_flush_get(void *data, u64 *val)
+{
+       if (link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE)
+               *val = 0;
+       else
+               *val = 1;
+
+       return 0;
+}
+
 DEFINE_DEBUGFS_ATTRIBUTE(fops_count_cache_flush, count_cache_flush_get,
                         count_cache_flush_set, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(fops_link_stack_flush, link_stack_flush_get,
+                        count_cache_flush_set, "%llu\n");
 
 static __init int count_cache_flush_debugfs_init(void)
 {
        debugfs_create_file_unsafe("count_cache_flush", 0600,
                                   arch_debugfs_dir, NULL,
                                   &fops_count_cache_flush);
+       debugfs_create_file_unsafe("link_stack_flush", 0600,
+                                  arch_debugfs_dir, NULL,
+                                  &fops_link_stack_flush);
        return 0;
 }
 device_initcall(count_cache_flush_debugfs_init);