From: Steven Rostedt <rostedt@goodmis.org>
To: "Tobin C. Harding" <me@tobin.cc>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Kees Cook <keescook@chromium.org>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 4/4] vsprintf: Add command line option debug_boot_weak_hash
Date: Wed, 13 Jun 2018 14:46:01 -0400 [thread overview]
Message-ID: <20180613144601.54855796@gandalf.local.home> (raw)
In-Reply-To: <1528763954-27731-5-git-send-email-me@tobin.cc>
On Tue, 12 Jun 2018 10:39:14 +1000
"Tobin C. Harding" <me@tobin.cc> wrote:
> +/* Make pointers available for printing early in the boot sequence. */
> +static int debug_boot_weak_hash __ro_after_init;
> +EXPORT_SYMBOL(debug_boot_weak_hash);
> +
> +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 +1715,12 @@ 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)) {
I was hoping to find a way to make the debug_boot_weak_hash into a
static_branch, but its setting is too early to have for a jump label.
I toyed with nesting this inside a static_branch too, but it seems too
much overkill.
Hence, I'll just punt and accept this patch as is ;-)
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-- Steve
> + 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 */
next prev parent reply other threads:[~2018-06-13 18:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-12 0:39 [PATCH v7 0/4] enable early printing of hashed pointers Tobin C. Harding
2018-06-12 0:39 ` [PATCH v7 1/4] random: Fix whitespace pre random-bytes work Tobin C. Harding
2018-06-12 0:39 ` [PATCH v7 2/4] random: Return nbytes filled from hw RNG Tobin C. Harding
2018-06-12 8:39 ` Andy Shevchenko
2018-06-12 18:28 ` Steven Rostedt
2018-06-12 21:42 ` Tobin C. Harding
2018-06-12 0:39 ` [PATCH v7 3/4] vsprintf: Use hw RNG for ptr_key Tobin C. Harding
2018-06-12 18:44 ` Steven Rostedt
2018-06-12 21:41 ` Tobin C. Harding
2018-06-12 0:39 ` [PATCH v7 4/4] vsprintf: Add command line option debug_boot_weak_hash Tobin C. Harding
2018-06-13 18:46 ` Steven Rostedt [this message]
2018-06-13 19:01 ` Steven Rostedt
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