[PATCH v5 2/3] mm: init: report memory auto-initialization features at boot time

Alexander Potapenko
2019-05-29T12:38:35Z

Print the currently enabled stack and heap initialization modes.

The possible options for stack are:
- "all" for CONFIG_INIT_STACK_ALL;
- "byref_all" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL;
- "byref" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF;
- "__user" for CONFIG_GCC_PLUGIN_STRUCTLEAK_USER;
- "off" otherwise.

Depending on the values of init_on_alloc and init_on_free boottime
options we also report "heap alloc" and "heap free" as "on"/"off".

In the init_on_free mode initializing pages at boot time may take some
time, so print a notice about that as well.

Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Sandeep Patil <sspatil@android.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-mm@kvack.org
Cc: linux-security-module@vger.kernel.org
---
init/main.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/init/main.c b/init/main.c
index 66a196c5e4c3..9d63ff1d48f3 100644
--- a/init/main.c
+++ b/init/main.c
@@ -520,6 +520,29 @@ static inline void initcall_debug_enable(void)
}
#endif

+/* Report memory auto-initialization states for this boot. */
+void __init report_meminit(void)
+{
+ const char *stack;
+
+ if (IS_ENABLED(CONFIG_INIT_STACK_ALL))
+ stack = "all";
+ else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL))
+ stack = "byref_all";
+ else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF))
+ stack = "byref";
+ else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER))
+ stack = "__user";
+ else
+ stack = "off";
+
+ pr_info("mem auto-init: stack:%s, heap alloc:%s, heap free:%s\n",
+ stack, want_init_on_alloc(GFP_KERNEL) ? "on" : "off",
+ want_init_on_free() ? "on" : "off");
+ if (want_init_on_free())
+ pr_info("Clearing system memory may take some time...\n");
+}
+
/*
* Set up kernel memory allocators
*/
@@ -530,6 +553,7 @@ static void __init mm_init(void)
* bigger than MAX_ORDER unless SPARSEMEM.
*/
page_ext_init_flatmem();
+ report_meminit();
mem_init();
kmem_cache_init();
pgtable_init();
--
2.22.0.rc1.257.g3120a18244-goog