Re: [PATCH v3 1/3] kprobes: Add text_alloc() and text_free()

From: Peter Zijlstra <peterz@infradead.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@vger.kernel.org,
	Andi Kleen <ak@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Jessica Yu <jeyu@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	Kees Cook <keescook@chromium.org>, Will Deacon <will@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Peter Collingbourne <pcc@google.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Stephen Boyd <sboyd@kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Miroslav Benes <mbenes@suse.cz>, Babu Moger <Babu.Moger@amd.com>,
	Omar Sandoval <osandov@fb.com>, Nayna Jain <nayna@linux.ibm.com>,
	Marco Elver <elver@google.com>, Brian Gerst <brgerst@gmail.com>,
	Jiri Kosina <jkosina@suse.cz>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH v3 1/3] kprobes: Add text_alloc() and text_free()
Date: Thu, 16 Jul 2020 11:02:53 +0200	[thread overview]
Message-ID: <20200716090253.GP10769@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200714223239.1543716-2-jarkko.sakkinen@linux.intel.com>

On Wed, Jul 15, 2020 at 01:32:27AM +0300, Jarkko Sakkinen wrote:
> +void *text_alloc(unsigned long size)
> +{
> +	void *p;
> +
> +	if (PAGE_ALIGN(size) > MODULES_LEN)
> +		return NULL;
> +
> +	p = __vmalloc_node_range(size, MODULE_ALIGN,
> +				    MODULES_VADDR + get_module_load_offset(),
> +				    MODULES_END, GFP_KERNEL,
> +				    PAGE_KERNEL, 0, NUMA_NO_NODE,
> +				    __builtin_return_address(0));
> +	if (p && (kasan_module_alloc(p, size) < 0)) {
> +		vfree(p);
> +		return NULL;
> +	}
> +
> +	return p;
> +}
> +
> +void text_free(void *region)
> +{
> +	/*
> +	 * This memory may be RO, and freeing RO memory in an interrupt is not
> +	 * supported by vmalloc.
> +	 */
> +	WARN_ON(in_interrupt());

I think that wants to be:

	lockdep_assert_irqs_enabled();

in_interrupt() isn't sufficient, interrupts must also not be disabled
when issuesing TLB invalidations.

> +
> +	vfree(region);
> +}