From: Peter Zijlstra <peterz@infradead.org>
To: "Christopher M. Riedl" <cmr@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, tglx@linutronix.de,
x86@kernel.org, linux-hardening@vger.kernel.org,
keescook@chromium.org
Subject: Re: [RESEND PATCH v4 10/11] powerpc: Protect patching_mm with a lock
Date: Thu, 6 May 2021 12:51:33 +0200 [thread overview]
Message-ID: <YJPKNSNVf34a39qC@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210506043452.9674-11-cmr@linux.ibm.com>
On Wed, May 05, 2021 at 11:34:51PM -0500, Christopher M. Riedl wrote:
> Powerpc allows for multiple CPUs to patch concurrently. When patching
> with STRICT_KERNEL_RWX a single patching_mm is allocated for use by all
> CPUs for the few times that patching occurs. Use a spinlock to protect
> the patching_mm from concurrent use.
>
> Modify patch_instruction() to acquire the lock, perform the patch op,
> and then release the lock.
>
> Also introduce {lock,unlock}_patching() along with
> patch_instruction_unlocked() to avoid per-iteration lock overhead when
> patch_instruction() is called in a loop. A follow-up patch converts some
> uses of patch_instruction() to use patch_instruction_unlocked() instead.
x86 uses text_mutex for all this, why not do the same?
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: "Christopher M. Riedl" <cmr@linux.ibm.com>
Cc: tglx@linutronix.de, x86@kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-hardening@vger.kernel.org,
keescook@chromium.org
Subject: Re: [RESEND PATCH v4 10/11] powerpc: Protect patching_mm with a lock
Date: Thu, 6 May 2021 12:51:33 +0200 [thread overview]
Message-ID: <YJPKNSNVf34a39qC@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210506043452.9674-11-cmr@linux.ibm.com>
On Wed, May 05, 2021 at 11:34:51PM -0500, Christopher M. Riedl wrote:
> Powerpc allows for multiple CPUs to patch concurrently. When patching
> with STRICT_KERNEL_RWX a single patching_mm is allocated for use by all
> CPUs for the few times that patching occurs. Use a spinlock to protect
> the patching_mm from concurrent use.
>
> Modify patch_instruction() to acquire the lock, perform the patch op,
> and then release the lock.
>
> Also introduce {lock,unlock}_patching() along with
> patch_instruction_unlocked() to avoid per-iteration lock overhead when
> patch_instruction() is called in a loop. A follow-up patch converts some
> uses of patch_instruction() to use patch_instruction_unlocked() instead.
x86 uses text_mutex for all this, why not do the same?
next prev parent reply other threads:[~2021-05-06 10:53 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 4:34 [RESEND PATCH v4 00/11] Use per-CPU temporary mappings for patching Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 01/11] powerpc: Add LKDTM accessor for patching addr Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 02/11] lkdtm/powerpc: Add test to hijack a patch mapping Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 03/11] x86_64: Add LKDTM accessor for patching addr Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 04/11] lkdtm/x86_64: Add test to hijack a patch mapping Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 05/11] powerpc/64s: Add ability to skip SLB preload Christopher M. Riedl
2021-06-21 3:13 ` Daniel Axtens
2021-07-01 3:48 ` Christopher M. Riedl
2021-07-01 3:48 ` Christopher M. Riedl
2021-07-01 4:15 ` Nicholas Piggin
2021-07-01 4:15 ` Nicholas Piggin
2021-07-01 5:28 ` Christopher M. Riedl
2021-07-01 5:28 ` Christopher M. Riedl
2021-07-01 6:04 ` Nicholas Piggin
2021-07-01 6:04 ` Nicholas Piggin
2021-07-01 6:53 ` Christopher M. Riedl
2021-07-01 6:53 ` Christopher M. Riedl
2021-07-01 7:37 ` Nicholas Piggin
2021-07-01 7:37 ` Nicholas Piggin
2021-07-01 11:30 ` Nicholas Piggin
2021-07-01 11:30 ` Nicholas Piggin
2021-07-09 4:55 ` Christopher M. Riedl
2021-07-09 4:55 ` Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 06/11] powerpc: Introduce temporary mm Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 07/11] powerpc/64s: Make slb_allocate_user() non-static Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 08/11] powerpc: Initialize and use a temporary mm for patching Christopher M. Riedl
2021-06-21 3:19 ` Daniel Axtens
2021-07-01 5:11 ` Christopher M. Riedl
2021-07-01 5:11 ` Christopher M. Riedl
2021-07-01 6:12 ` Nicholas Piggin
2021-07-01 6:12 ` Nicholas Piggin
2021-07-01 7:02 ` Christopher M. Riedl
2021-07-01 7:02 ` Christopher M. Riedl
2021-07-01 7:51 ` Nicholas Piggin
2021-07-01 7:51 ` Nicholas Piggin
2021-07-09 5:03 ` Christopher M. Riedl
2021-07-09 5:03 ` Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 09/11] lkdtm/powerpc: Fix code patching hijack test Christopher M. Riedl
2021-05-06 4:34 ` [RESEND PATCH v4 10/11] powerpc: Protect patching_mm with a lock Christopher M. Riedl
2021-05-06 10:51 ` Peter Zijlstra [this message]
2021-05-06 10:51 ` Peter Zijlstra
2021-05-07 20:03 ` Christopher M. Riedl
2021-05-07 20:03 ` Christopher M. Riedl
2021-05-07 22:26 ` Peter Zijlstra
2021-05-06 4:34 ` [RESEND PATCH v4 11/11] powerpc: Use patch_instruction_unlocked() in loops Christopher M. Riedl
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