From: Peter Zijlstra <peterz@infradead•org>
To: Mike Rapoport <rppt@kernel•org>
Cc: Mark Rutland <mark.rutland@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Song Liu <song@kernel•org>,
linux-riscv@lists•infradead.org, Will Deacon <will@kernel•org>,
linux-arch@vger•kernel.org, Helge Deller <deller@gmx•de>,
x86@kernel•org, Russell King <linux@armlinux•org.uk>,
Christoph Hellwig <hch@infradead•org>,
linux-trace-kernel@vger•kernel.org, Arnd Bergmann <arnd@arndb•de>,
Steven Rostedt <rostedt@goodmis•org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios•com>,
Andy Lutomirski <luto@kernel•org>,
Thomas Gleixner <tglx@linutronix•de>,
Andrew Morton <akpm@linux-foundation•org>,
linux-arm-kernel@lists•infradead.org,
Lorenzo Stoakes <lstoakes@gmail•com>,
linux-parisc@vger•kernel.org, linux-mm@kvack•org,
linux-kernel@vger•kernel.org,
Luis Chamberlain <mcgrof@kernel•org>,
Uladzislau Rezki <urezki@gmail•com>,
Palmer Dabbelt <palmer@dabbelt•com>,
Masami Hiramatsu <mhiramat@kernel•org>,
bpf@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
linux-modules@vger•kernel.org
Subject: Re: [RFC PATCH 6/7] execmem: add support for cache of large ROX pages
Date: Tue, 16 Apr 2024 09:52:34 +0200 [thread overview]
Message-ID: <20240416075234.GA31647@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <Zh1dKkFr6zdBh2Kz@kernel.org>
On Mon, Apr 15, 2024 at 08:00:26PM +0300, Mike Rapoport wrote:
> On Mon, Apr 15, 2024 at 12:47:50PM +0200, Peter Zijlstra wrote:
> > On Thu, Apr 11, 2024 at 07:05:25PM +0300, Mike Rapoport wrote:
> >
> > > To populate the cache, a writable large page is allocated from vmalloc with
> > > VM_ALLOW_HUGE_VMAP, filled with invalid instructions and then remapped as
> > > ROX.
> >
> > > +static void execmem_invalidate(void *ptr, size_t size, bool writable)
> > > +{
> > > + if (execmem_info->invalidate)
> > > + execmem_info->invalidate(ptr, size, writable);
> > > + else
> > > + memset(ptr, 0, size);
> > > +}
> >
> > +static void execmem_invalidate(void *ptr, size_t size, bool writeable)
> > +{
> > + /* fill memory with INT3 instructions */
> > + if (writeable)
> > + memset(ptr, 0xcc, size);
> > + else
> > + text_poke_set(ptr, 0xcc, size);
> > +}
> >
> > Thing is, 0xcc (aka INT3_INSN_OPCODE) is not an invalid instruction.
> > It raises #BP not #UD.
>
> Do you mean that _invalidate is a poor name choice or that it's necessary
> to use an instruction that raises #UD?
Poor naming, mostly. #BP handler will still scream bloody murder if the
site is otherwise unclaimed.
It just isn't an invalid instruction.
next prev parent reply other threads:[~2024-04-16 7:53 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 16:05 [RFC PATCH 0/7] x86/module: use large ROX pages for text allocations Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 1/7] asm-generic: introduce text-patching.h Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 2/7] mm: vmalloc: don't account for number of nodes for HUGE_VMAP allocations Mike Rapoport
2024-04-12 6:07 ` Christophe Leroy
2024-04-14 7:34 ` Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 3/7] module: prepare to handle ROX allocations for text Mike Rapoport
2024-04-16 9:36 ` Nadav Amit
2024-04-18 10:20 ` Mike Rapoport
2024-04-18 19:31 ` [RFC PATCH 3/7] module: [ Nadav Amit
2024-04-18 19:44 ` Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 4/7] ftrace: Add swap_func to ftrace_process_locs() Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 5/7] x86/module: perpare module loading for ROX allocations of text Mike Rapoport
2024-04-12 9:08 ` Ingo Molnar
2024-04-14 7:35 ` Mike Rapoport
2024-04-15 10:43 ` Peter Zijlstra
2024-04-15 17:04 ` Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 6/7] execmem: add support for cache of large ROX pages Mike Rapoport
2024-04-15 10:47 ` Peter Zijlstra
2024-04-15 17:00 ` Mike Rapoport
2024-04-16 7:52 ` Peter Zijlstra [this message]
2024-04-18 10:23 ` Mike Rapoport
2024-04-11 16:05 ` [RFC PATCH 7/7] x86/module: enable ROX caches for module text Mike Rapoport
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