diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 8 | ||||
| -rw-r--r-- | lib/vsprintf.c | 17 |
2 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index efc7aa7a0670..0c8f7889efa1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -748,6 +748,14 @@ debug [KNL] Enable kernel debugging (events log level). + debug_boot_weak_hash + [KNL] Enable printing [hashed] pointers early in the + boot sequence. If enabled, we use a weak hash instead + of siphash to hash pointers. Use this option if you are + seeing instances of '(___ptrval___)') and need to see a + value (hashed pointer) instead. Cryptographically + insecure, please do not use on production kernels. + debug_locks_verbose= [KNL] verbose self-tests Format=<0|1> diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 6c1fb395bddf..1ee2829f3b54 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1651,6 +1651,17 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, return widen_string(buf, buf - buf_start, end, spec); } +/* Make pointers available for printing early in the boot sequence. */ +static int debug_boot_weak_hash __ro_after_init; + +static int __init debug_boot_weak_hash_enable(char *str) +{ + debug_boot_weak_hash = 1; + pr_info("debug_boot_weak_hash enabled\n"); + return 0; +} +early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable); + static DEFINE_STATIC_KEY_TRUE(not_filled_random_ptr_key); static siphash_key_t ptr_key __read_mostly; @@ -1703,6 +1714,12 @@ static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec) const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)"; unsigned long hashval; + /* When debugging early boot use non-cryptographically secure hash. */ + if (unlikely(debug_boot_weak_hash)) { + hashval = hash_long((unsigned long)ptr, 32); + return pointer_string(buf, end, (const void *)hashval, spec); + } + if (static_branch_unlikely(¬_filled_random_ptr_key)) { spec.field_width = 2 * sizeof(ptr); /* string length must be less than default_width */ |