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authorJosh Poimboeuf <jpoimboe@redhat.com>2018-02-20 11:37:51 -0600
committerIngo Molnar <mingo@kernel.org>2018-02-21 16:54:05 +0100
commit33352244706369ea6736781ae41fe41692eb69bb (patch)
treec3ea4269b95e89e4594b2023e7167a2ba8b0fa59 /kernel
parentf3d415ea46968ae1f9cbb9e201601d7207ce74c7 (diff)
jump_label: Explicitly disable jump labels in __init code
After initmem has been freed, any jump labels in __init code are prevented from being written to by the kernel_text_address() check in __jump_label_update(). However, this check is quite broad. If kernel_text_address() were to return false for any other reason, the jump label write would fail silently with no warning. For jump labels in module init code, entry->code is set to zero to indicate that the entry is disabled. Do the same thing for core kernel init code. This makes the behavior more consistent, and will also make it more straightforward to detect non-init jump label write failures in the next patch. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/c52825c73f3a174e8398b6898284ec20d4deb126.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/jump_label.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index b4517095db6a..b71776576a66 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -16,6 +16,7 @@
#include <linux/jump_label_ratelimit.h>
#include <linux/bug.h>
#include <linux/cpu.h>
+#include <asm/sections.h>
#ifdef HAVE_JUMP_LABEL
@@ -417,6 +418,20 @@ void __init jump_label_init(void)
cpus_read_unlock();
}
+/* Disable any jump label entries in __init code */
+void __init jump_label_invalidate_init(void)
+{
+ struct jump_entry *iter_start = __start___jump_table;
+ struct jump_entry *iter_stop = __stop___jump_table;
+ struct jump_entry *iter;
+
+ for (iter = iter_start; iter < iter_stop; iter++) {
+ if (iter->code >= (unsigned long)_sinittext &&
+ iter->code < (unsigned long)_einittext)
+ iter->code = 0;
+ }
+}
+
#ifdef CONFIG_MODULES
static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
@@ -633,6 +648,7 @@ static void jump_label_del_module(struct module *mod)
}
}
+/* Disable any jump label entries in module init code */
static void jump_label_invalidate_module_init(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;