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From: Nadav Amit <namit@vmware.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Damian Tometzki <linux_dti@icloud.com>,
	linux-integrity <linux-integrity@vger.kernel.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Linux-MM <linux-mm@kvack.org>, Will Deacon <will.deacon@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	"kristen@linux.intel.com" <kristen@linux.intel.com>,
	"deneen.t.dock@intel.com" <deneen.t.dock@intel.com>,
	Kees Cook <keescook@chromium.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 01/17] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()"
Date: Fri, 25 Jan 2019 18:28:04 +0000	[thread overview]
Message-ID: <BEFCBDFB-F08F-441D-8BCC-07E5F448D9D2@vmware.com> (raw)
In-Reply-To: <20190125093052.GA27998@zn.tnic>

> On Jan 25, 2019, at 1:30 AM, Borislav Petkov <bp@alien8.de> wrote:
> 
> On Wed, Jan 16, 2019 at 04:32:43PM -0800, Rick Edgecombe wrote:
>> From: Nadav Amit <namit@vmware.com>
>> 
>> text_mutex is currently expected to be held before text_poke() is
>> called, but we kgdb does not take the mutex, and instead *supposedly*
>> ensures the lock is not taken and will not be acquired by any other core
>> while text_poke() is running.
>> 
>> The reason for the "supposedly" comment is that it is not entirely clear
>> that this would be the case if gdb_do_roundup is zero.
> 
> I guess that variable name is "kgdb_do_roundup” ?

Yes. Will fix.

> 
>> This patch creates two wrapper functions, text_poke() and
> 
> Avoid having "This patch" or "This commit" in the commit message. It is
> tautologically useless.
> 
> Also, do
> 
> $ git grep 'This patch' Documentation/process
> 
> for more details.

Ok.

>> 
>> +void *text_poke_kgdb(void *addr, const void *opcode, size_t len)
> 
> text_poke_unlocked() I guess. I don't think kgdb is that special that it
> needs its own function flavor.

Tglx suggested this naming to prevent anyone from misusing text_poke_kdgb().
This is a very specific use-case that nobody else should need.

Regards,
Nadav

  reply	other threads:[~2019-01-25 18:28 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-17  0:32 [PATCH 00/17] Merge text_poke fixes and executable lockdowns Rick Edgecombe
2019-01-17  0:32 ` [PATCH 01/17] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Rick Edgecombe
2019-01-17  6:47   ` Masami Hiramatsu
2019-01-17 21:15     ` hpa
2019-01-17 22:39       ` Nadav Amit
2019-01-17 22:59         ` hpa
2019-01-17 23:14           ` Nadav Amit
2019-01-25  9:30   ` Borislav Petkov
2019-01-25 18:28     ` Nadav Amit [this message]
2019-01-17  0:32 ` [PATCH 02/17] x86/jump_label: Use text_poke_early() during early init Rick Edgecombe
2019-01-17  0:32 ` [PATCH 03/17] x86/mm: temporary mm struct Rick Edgecombe
2019-01-17  0:32 ` [PATCH 04/17] fork: provide a function for copying init_mm Rick Edgecombe
2019-01-17  0:32 ` [PATCH 05/17] x86/alternative: initializing temporary mm for patching Rick Edgecombe
2019-01-17  0:32 ` [PATCH 06/17] x86/alternative: use temporary mm for text poking Rick Edgecombe
2019-01-17 20:27   ` Andy Lutomirski
2019-01-17 20:47     ` Andy Lutomirski
2019-01-17 21:43       ` Nadav Amit
2019-01-17 22:29         ` Nadav Amit
2019-01-17 22:31         ` hpa
2019-01-17  0:32 ` [PATCH 07/17] x86/kgdb: avoid redundant comparison of patched code Rick Edgecombe
2019-01-17  0:32 ` [PATCH 08/17] x86/ftrace: set trampoline pages as executable Rick Edgecombe
2019-02-06 16:22   ` Steven Rostedt
2019-02-06 17:33     ` Nadav Amit
2019-02-06 17:41       ` Steven Rostedt
2019-01-17  0:32 ` [PATCH 09/17] x86/kprobes: Instruction pages initialization enhancements Rick Edgecombe
2019-01-17  6:51   ` Masami Hiramatsu
2019-01-17  0:32 ` [PATCH 10/17] x86: avoid W^X being broken during modules loading Rick Edgecombe
2019-01-17  0:32 ` [PATCH 11/17] x86/jump-label: remove support for custom poker Rick Edgecombe
2019-01-17  0:32 ` [PATCH 12/17] x86/alternative: Remove the return value of text_poke_*() Rick Edgecombe
2019-01-17  0:32 ` [PATCH 13/17] Add set_alias_ function and x86 implementation Rick Edgecombe
2019-01-17  0:32 ` [PATCH 14/17] mm: Make hibernate handle unmapped pages Rick Edgecombe
2019-01-17  9:39   ` Pavel Machek
2019-01-17 22:16     ` Edgecombe, Rick P
2019-01-17 23:41       ` Pavel Machek
2019-01-17 23:48         ` Edgecombe, Rick P
2019-01-18  8:16           ` Pavel Machek
2019-01-17  0:32 ` [PATCH 15/17] vmalloc: New flags for safe vfree on special perms Rick Edgecombe
2019-01-17  0:32 ` [PATCH 16/17] Plug in new special vfree flag Rick Edgecombe
2019-02-06 16:23   ` Steven Rostedt
2019-02-07 17:33     ` Edgecombe, Rick P
2019-02-07 17:49       ` Steven Rostedt
2019-02-07 18:20         ` Edgecombe, Rick P
2019-01-17  0:32 ` [PATCH 17/17] module: Prevent module removal racing with text_poke() Rick Edgecombe
2019-01-17  7:54   ` Masami Hiramatsu
2019-01-17 18:07     ` Nadav Amit
2019-01-17 23:44       ` H. Peter Anvin
2019-01-18  8:23       ` Masami Hiramatsu
2019-01-17 23:58     ` H. Peter Anvin
2019-01-18  1:15       ` Nadav Amit
2019-01-18 13:32         ` Masami Hiramatsu
2019-01-17 13:21 ` [PATCH 00/17] Merge text_poke fixes and executable lockdowns Peter Zijlstra

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