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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 11:04:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 11:04:36 -0800
commitb2bec7d8a42a3885d525e821d9354b6b08fd6adf (patch)
tree8198d77e5b2fb8fc645ae42662b93a575910a032 /lib
parent783955f03de770e94a1200b8f719975f8768e76c (diff)
parent16182ac1f02c8a5fc9753f9b8b5f3ef8c01707d8 (diff)
downloadlinux-b2bec7d8a42a3885d525e821d9354b6b08fd6adf.tar.bz2
Merge tag 'printk-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek: - New "no_hash_pointers" kernel parameter causes that %p shows raw pointer values instead of hashed ones. It is intended only for debugging purposes. Misuse is prevented by a fat warning message that is inspired by trace_printk(). - Prevent a possible deadlock when flushing printk_safe buffers during panic(). - Fix performance regression caused by the lockless printk ringbuffer. It was visible with huge log buffer and long messages. - Documentation fix-up. * tag 'printk-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: lib/vsprintf: no_hash_pointers prints all addresses as unhashed kselftest: add support for skipped tests lib: use KSTM_MODULE_GLOBALS macro in kselftest drivers printk: avoid prb_first_valid_seq() where possible printk: fix deadlock when kernel panic printk: rectify kernel-doc for prb_rec_init_wr()
Diffstat (limited to 'lib')
-rw-r--r--lib/test_bitmap.c3
-rw-r--r--lib/test_printf.c12
-rw-r--r--lib/vsprintf.c36
3 files changed, 45 insertions, 6 deletions
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 4425a1dd4ef1..0ea0e8258f14 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -16,8 +16,7 @@
#include "../tools/testing/selftests/kselftest_module.h"
-static unsigned total_tests __initdata;
-static unsigned failed_tests __initdata;
+KSTM_MODULE_GLOBALS();
static char pbl_buffer[PAGE_SIZE] __initdata;
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 7d60f24240a4..95a2f82427c7 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -30,11 +30,13 @@
#define PAD_SIZE 16
#define FILL_CHAR '$'
-static unsigned total_tests __initdata;
-static unsigned failed_tests __initdata;
+KSTM_MODULE_GLOBALS();
+
static char *test_buffer __initdata;
static char *alloced_buffer __initdata;
+extern bool no_hash_pointers;
+
static int __printf(4, 0) __init
do_test(int bufsize, const char *expect, int elen,
const char *fmt, va_list ap)
@@ -301,6 +303,12 @@ plain(void)
{
int err;
+ if (no_hash_pointers) {
+ pr_warn("skipping plain 'p' tests");
+ skipped_tests += 2;
+ return;
+ }
+
err = plain_hash();
if (err) {
pr_warn("plain 'p' does not appear to be hashed\n");
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3b53c73580c5..41ddc353ebb8 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2090,6 +2090,32 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
return widen_string(buf, buf - buf_start, end, spec);
}
+/* Disable pointer hashing if requested */
+bool no_hash_pointers __ro_after_init;
+EXPORT_SYMBOL_GPL(no_hash_pointers);
+
+static int __init no_hash_pointers_enable(char *str)
+{
+ no_hash_pointers = true;
+
+ pr_warn("**********************************************************\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("** **\n");
+ pr_warn("** This system shows unhashed kernel memory addresses **\n");
+ pr_warn("** via the console, logs, and other interfaces. This **\n");
+ pr_warn("** might reduce the security of your system. **\n");
+ pr_warn("** **\n");
+ pr_warn("** If you see this message and you are not debugging **\n");
+ pr_warn("** the kernel, report this immediately to your system **\n");
+ pr_warn("** administrator! **\n");
+ pr_warn("** **\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("**********************************************************\n");
+
+ return 0;
+}
+early_param("no_hash_pointers", no_hash_pointers_enable);
+
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
@@ -2297,8 +2323,14 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
}
- /* default is to _not_ leak addresses, hash before printing */
- return ptr_to_id(buf, end, ptr, spec);
+ /*
+ * default is to _not_ leak addresses, so hash before printing,
+ * unless no_hash_pointers is specified on the command line.
+ */
+ if (unlikely(no_hash_pointers))
+ return pointer_string(buf, end, ptr, spec);
+ else
+ return ptr_to_id(buf, end, ptr, spec);
}
/*