linux-kernel - Re: [PATCH v1 2/7] arm64: introduce interfaces to hotpatch kernel and module code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Sep 2013 10:35:35 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Jiang Liu <jiang.liu@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/7] arm64: introduce interfaces to hotpatch kernel
 and module code

On Wed, 25 Sep 2013 18:44:22 +0800
Jiang Liu <liuj97@...il.com> wrote:
> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
> index 8541c3a..50facfc 100644
> --- a/arch/arm64/kernel/insn.c
> +++ b/arch/arm64/kernel/insn.c
> @@ -15,6 +15,8 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  #include <linux/kernel.h>
> +#include <linux/stop_machine.h>
> +#include <asm/cacheflush.h>
>  #include <asm/insn.h>
>  
>  static int aarch64_insn_cls[] = {
> @@ -69,3 +71,65 @@ bool __kprobes aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn)
>  	return __aarch64_insn_hotpatch_safe(old_insn) &&
>  	       __aarch64_insn_hotpatch_safe(new_insn);
>  }
> +
> +struct aarch64_insn_patch {
> +	void	*text_addr;
> +	u32	*new_insns;
> +	int	insn_cnt;
> +};
> +
> +int __kprobes __aarch64_insn_patch_text(void *addr, u32 *insns, int cnt)
> +{
> +	int i;
> +	u32 *tp = addr;
> +
> +	/* instructions must be word aligned */
> +	if (cnt <= 0 || ((uintptr_t)addr & 0x3))
> +		return -EINVAL;

On aarch64, are instructions always word aligned? If not, it should be
safe for stop machine to modify non word aligned instructions, but this
patch looks like it doesn't allow stop_machine() to do so.

-- Steve

> +
> +	for (i = 0; i < cnt; i++)
> +		tp[i] = insns[i];
> +
> +	flush_icache_range((uintptr_t)tp, (uintptr_t)tp + cnt * sizeof(u32));
> +
> +	return 0;
> +}
> +
> +static int __kprobes aarch64_insn_patch_text_cb(void *arg)
> +{
> +	struct aarch64_insn_patch *pp = arg;
> +
> +	return __aarch64_insn_patch_text(pp->text_addr, pp->new_insns,
> +					 pp->insn_cnt);
> +}
> +
> +int __kprobes aarch64_insn_patch_text(void *addr, u32 *insns, int cnt)
> +{
> +	int ret;
> +	bool safe = false;
> +
> +	/* instructions must be word aligned */
> +	if (cnt <= 0 || ((uintptr_t)addr & 0x3))
> +		return -EINVAL;
> +
> +	if (cnt == 1)
> +		safe = aarch64_insn_hotpatch_safe(*(u32 *)addr, insns[0]);
> +
> +	if (safe) {
> +		ret = __aarch64_insn_patch_text(addr, insns, cnt);
> +	} else {
> +		struct aarch64_insn_patch patch = {
> +			.text_addr = addr,
> +			.new_insns = insns,
> +			.insn_cnt = cnt,
> +		};
> +
> +		/*
> +		 * Execute __aarch64_insn_patch_text() on every online CPU,
> +		 * which ensure serialization among all online CPUs.
> +		 */
> +		ret = stop_machine(aarch64_insn_patch_text_cb, &patch, NULL);
> +	}
> +
> +	return ret;
> +}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/