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[PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message

Started byBorislav Petkov <bp@alien8.de>
First post2016-07-05 00:40 +0200
Last post2016-07-06 15:20 +0200
Articles 5 — 3 participants

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  [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message Borislav Petkov <bp@alien8.de> - 2016-07-05 00:40 +0200
    [PATCH -v2 1/3] x86/dumpstack: Honor supplied @regs arg Borislav Petkov <bp@alien8.de> - 2016-07-05 00:40 +0200
      [tip:x86/debug] x86/dumpstack: Honor supplied @regs arg tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-07-08 14:10 +0200
    Re: [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message Andy Lutomirski <luto@amacapital.net> - 2016-07-06 15:00 +0200
      Re: [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error  message Borislav Petkov <bp@alien8.de> - 2016-07-06 15:20 +0200

#1436627 — [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message

FromBorislav Petkov <bp@alien8.de>
Date2016-07-05 00:40 +0200
Subject[PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message
Message-ID<rRkGZ-2Z3-5@gated-at.bofh.it>
From: Borislav Petkov <bp@suse.de>

Hi all,

here's v2 with review feedback integrated.

Changelog:

v1:

here's a simple patchset improving the error message we're dumping when
an unchecked MSR is being done. Patch 3 has an example which explains
the improvement in detail.


Andy Lutomirski (1):
  x86/dumpstack: Honor supplied @regs arg

Borislav Petkov (2):
  printk: Make the printk*once() variants return a value
  x86/dumpstack: Add show_stack_regs() and use it

 arch/x86/include/asm/kdebug.h  |  1 +
 arch/x86/kernel/dumpstack.c    |  5 +++++
 arch/x86/kernel/dumpstack_32.c |  4 +++-
 arch/x86/kernel/dumpstack_64.c |  4 +++-
 arch/x86/mm/extable.c          | 13 ++++++++-----
 include/linux/printk.h         | 17 ++++++++++++-----
 6 files changed, 32 insertions(+), 12 deletions(-)

-- 
2.7.3

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#1436628 — [PATCH -v2 1/3] x86/dumpstack: Honor supplied @regs arg

FromBorislav Petkov <bp@alien8.de>
Date2016-07-05 00:40 +0200
Subject[PATCH -v2 1/3] x86/dumpstack: Honor supplied @regs arg
Message-ID<rRkGZ-2Z3-17@gated-at.bofh.it>
In reply to#1436627
From: Andy Lutomirski <luto@kernel.org>

The comment suggests that show_stack(NULL, NULL) should backtrace the
current context, but the code doesn't match the comment. If regs are
given, start the "Stack:" hexdump at regs->sp.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/efcd79bf4106d61f1cd258c2caa87f3a0618eeac.1466036668.git.luto@kernel.org
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/dumpstack_32.c | 4 +++-
 arch/x86/kernel/dumpstack_64.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index fef917e79b9d..948d77da3881 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -96,7 +96,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	int i;
 
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index d558a8a49016..a81e1ef73bf2 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -264,7 +264,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	 * back trace for this cpu:
 	 */
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;
-- 
2.7.3

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#1439366 — [tip:x86/debug] x86/dumpstack: Honor supplied @regs arg

Fromtip-bot for Andy Lutomirski <tipbot@zytor.com>
Date2016-07-08 14:10 +0200
Subject[tip:x86/debug] x86/dumpstack: Honor supplied @regs arg
Message-ID<rSCLv-4Br-11@gated-at.bofh.it>
In reply to#1436628
Commit-ID:  ef16dd0c2a523d2e3975bb1bea9f5727e3e7146f
Gitweb:     http://git.kernel.org/tip/ef16dd0c2a523d2e3975bb1bea9f5727e3e7146f
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Tue, 5 Jul 2016 00:31:25 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 8 Jul 2016 11:33:18 +0200

x86/dumpstack: Honor supplied @regs arg

The comment suggests that show_stack(NULL, NULL) should backtrace the
current context, but the code doesn't match the comment. If regs are
given, start the "Stack:" hexdump at regs->sp.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1467671487-10344-2-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/efcd79bf4106d61f1cd258c2caa87f3a0618eeac.1466036668.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/dumpstack_32.c | 4 +++-
 arch/x86/kernel/dumpstack_64.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index fef917e..948d77d 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -96,7 +96,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	int i;
 
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index d558a8a..a81e1ef 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -264,7 +264,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	 * back trace for this cpu:
 	 */
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;

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#1437692

FromAndy Lutomirski <luto@amacapital.net>
Date2016-07-06 15:00 +0200
Message-ID<rRUAN-Sa-15@gated-at.bofh.it>
In reply to#1436627
On Mon, Jul 4, 2016 at 3:31 PM, Borislav Petkov <bp@alien8.de> wrote:
> From: Borislav Petkov <bp@suse.de>
>
> Hi all,
>
> here's v2 with review feedback integrated.

Just a silly overall thought: WARN_ON will be noticed by the 0day bot
and similar tools.  This series changes the message text a bit -- is
it still noticed?

--Andy

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#1437702 — Re: [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message

FromBorislav Petkov <bp@alien8.de>
Date2016-07-06 15:20 +0200
SubjectRe: [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message
Message-ID<rRUUa-1e4-13@gated-at.bofh.it>
In reply to#1437692
On Wed, Jul 06, 2016 at 05:58:35AM -0700, Andy Lutomirski wrote:
> On Mon, Jul 4, 2016 at 3:31 PM, Borislav Petkov <bp@alien8.de> wrote:
> > From: Borislav Petkov <bp@suse.de>
> >
> > Hi all,
> >
> > here's v2 with review feedback integrated.
> 
> Just a silly overall thought: WARN_ON will be noticed by the 0day bot
> and similar tools.  This series changes the message text a bit -- is
> it still noticed?

No idea, let's CC them.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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