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From: Andy Lutomirski <luto@kernel.org>
To: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jessica Yu <jeyu@kernel.org>, bpf <bpf@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrew Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>, X86 ML <x86@kernel.org>,
	Mike Rapoport <rppt@kernel.org>, Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Elena Reshetova <elena.reshetova@intel.com>,
	Weiny Ira <ira.weiny@intel.com>
Subject: Re: [PATCH RFC 01/10] vmalloc: Add basic perm alloc implementation
Date: Sat, 21 Nov 2020 20:10:16 -0800	[thread overview]
Message-ID: <CALCETrUjpdSGg0T8vehkXszDJKx5AS0BHP9qFRsakPABzPM2GA@mail.gmail.com> (raw)
In-Reply-To: <20201120202426.18009-2-rick.p.edgecombe@intel.com>

On Fri, Nov 20, 2020 at 12:30 PM Rick Edgecombe
<rick.p.edgecombe@intel.com> wrote:
>
> In order to allow for future arch specific optimizations for vmalloc
> permissions, first add an implementation of a new interface that will
> work cross arch by using the existing set_memory_() functions.
>
> When allocating some memory that will be RO, for example it should be used
> like:
>
> /* Reserve va */
> struct perm_allocation *alloc = perm_alloc(vstart, vend, page_cnt, PERM_R);

I'm sure I could reverse-engineer this from the code, but:

Where do vstart and vend come from?  Does perm_alloc() allocate memory
or just virtual addresses?  Is the caller expected to call vmalloc()?
How does one free this thing?

> unsigned long ro = (unsigned long)perm_alloc_address(alloc);
>
> /* Write to writable address */
> strcpy((char *)perm_writable_addr(alloc, ro), "Some data to be RO");
> /* Signal that writing is done and mapping should be live */
> perm_writable_finish(alloc);
> /* Print from RO address */
> printk("Read only data is: %s\n", (char *)ro);
>

  reply	other threads:[~2020-11-22  4:10 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20 20:24 [PATCH RFC 00/10] New permission vmalloc interface Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 01/10] vmalloc: Add basic perm alloc implementation Rick Edgecombe
2020-11-22  4:10   ` Andy Lutomirski [this message]
2020-11-23  0:01     ` Edgecombe, Rick P
2020-11-24 10:16       ` Christoph Hellwig
2020-11-24 20:00         ` Edgecombe, Rick P
2020-11-23  9:00   ` Christoph Hellwig
2020-11-23 20:44     ` Edgecombe, Rick P
2020-11-24 10:19       ` hch
2020-11-24 19:59         ` Edgecombe, Rick P
2020-12-04 23:24   ` Sean Christopherson
2020-12-07 23:55     ` Edgecombe, Rick P
2020-11-20 20:24 ` [PATCH RFC 02/10] bpf: Use perm_alloc() for BPF JIT filters Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 03/10] module: Use perm_alloc() for modules Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 04/10] module: Support separate writable allocation Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 05/10] x86/modules: Use real perm_allocations Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 06/10] x86/alternatives: Handle perm_allocs for modules Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 07/10] x86/unwind: Unwind orc at module writable address Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 08/10] jump_label: Handle " Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 09/10] ftrace: Use " Rick Edgecombe
2020-11-20 20:24 ` [PATCH RFC 10/10] vmalloc: Add perm_alloc x86 implementation Rick Edgecombe
2020-11-22 15:29   ` [vmalloc] 377647beed: WARNING:at_arch/x86/kernel/ftrace.c:#ftrace_verify_code kernel test robot

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