From: Nadav Amit <namit@vmware.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>,
<x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
<linux-arch@vger.kernel.org>, Nadav Amit <namit@vmware.com>,
Andy Lutomirski <luto@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: [RFC PATCH 1/6] x86/alternative: assert text_mutex is taken
Date: Wed, 29 Aug 2018 01:11:42 -0700 [thread overview]
Message-ID: <20180829081147.184610-2-namit@vmware.com> (raw)
In-Reply-To: <20180829081147.184610-1-namit@vmware.com>
Use lockdep to ensure that text_mutex is taken when text_poke() is
called.
Actually it is not always taken, specifically when it is called by kgdb,
so take the lock in these cases.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
arch/x86/kernel/alternative.c | 1 +
arch/x86/kernel/kgdb.c | 9 +++++++++
2 files changed, 10 insertions(+)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 014f214da581..916c11b410c4 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -699,6 +699,7 @@ void *text_poke(void *addr, const void *opcode, size_t len)
* pages as they are not yet initialized.
*/
BUG_ON(!after_bootmem);
+ lockdep_assert_held(&text_mutex);
if (!core_kernel_text((unsigned long)addr)) {
pages[0] = vmalloc_to_page(addr);
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8e36f249646e..60b99c76086c 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -768,8 +768,12 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
*/
if (mutex_is_locked(&text_mutex))
return -EBUSY;
+
+ /* Take the mutex to avoid lockdep assertion failures. */
+ mutex_lock(&text_mutex);
text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
BREAK_INSTR_SIZE);
+ mutex_unlock(&text_mutex);
err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
if (err)
return err;
@@ -793,7 +797,12 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
*/
if (mutex_is_locked(&text_mutex))
goto knl_write;
+
+ /* Take the mutex to avoid lockdep assertion failures. */
+ mutex_lock(&text_mutex);
text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
+ mutex_unlock(&text_mutex);
+
err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
goto knl_write;
--
2.17.1
next prev parent reply other threads:[~2018-08-29 8:13 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 8:11 [RFC PATCH 0/6] x86: text_poke() fixes Nadav Amit
2018-08-29 8:11 ` Nadav Amit [this message]
2018-08-29 8:59 ` [RFC PATCH 1/6] x86/alternative: assert text_mutex is taken Masami Hiramatsu
2018-08-29 17:11 ` Nadav Amit
2018-08-29 19:36 ` Nadav Amit
2018-08-29 20:13 ` Sean Christopherson
2018-08-29 20:44 ` Nadav Amit
2018-08-29 21:00 ` Sean Christopherson
2018-08-29 22:56 ` Nadav Amit
2018-08-30 2:26 ` Masami Hiramatsu
2018-08-30 5:23 ` Nadav Amit
2018-08-29 8:11 ` [RFC PATCH 2/6] x86/mm: temporary mm struct Nadav Amit
2018-08-29 9:49 ` Masami Hiramatsu
2018-08-29 15:41 ` Andy Lutomirski
2018-08-29 16:54 ` Nadav Amit
2018-08-29 21:38 ` Andy Lutomirski
2018-08-30 1:38 ` Masami Hiramatsu
2018-08-30 1:59 ` Andy Lutomirski
2018-08-31 4:42 ` Masami Hiramatsu
2018-08-29 15:46 ` Andy Lutomirski
2018-08-29 8:11 ` [RFC PATCH 3/6] fork: provide a function for copying init_mm Nadav Amit
2018-08-29 9:54 ` Masami Hiramatsu
2018-08-29 8:11 ` [RFC PATCH 4/6] x86/alternatives: initializing temporary mm for patching Nadav Amit
2018-08-29 13:21 ` Masami Hiramatsu
2018-08-29 17:45 ` Nadav Amit
2018-08-29 8:11 ` [RFC PATCH 5/6] x86/alternatives: use temporary mm for text poking Nadav Amit
2018-08-29 9:28 ` Peter Zijlstra
2018-08-29 15:46 ` Andy Lutomirski
2018-08-29 16:14 ` Peter Zijlstra
2018-08-29 16:32 ` Andy Lutomirski
2018-08-29 16:37 ` Dave Hansen
2018-08-29 8:11 ` [RFC PATCH 6/6] x86/alternatives: remove text_poke() return value Nadav Amit
2018-08-29 9:52 ` Masami Hiramatsu
2018-08-29 17:15 ` Nadav Amit
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