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Re: [PATCH v2 2.6.38-rc8-tip 6/20] 6: x86: analyze instruction and determine fixups.
- From: Thomas Gleixner <tglx at linutronix dot de>
- To: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>
- Cc: Peter Zijlstra <peterz at infradead dot org>, Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Andi Kleen <andi at firstfloor dot org>, Christoph Hellwig <hch at infradead dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Oleg Nesterov <oleg at redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, SystemTap <systemtap at sources dot redhat dot com>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, LKML <linux-kernel at vger dot kernel dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Tue, 15 Mar 2011 15:36:59 +0100 (CET)
- Subject: Re: [PATCH v2 2.6.38-rc8-tip 6/20] 6: x86: analyze instruction and determine fixups.
- References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133507.27435.71382.sendpatchset@localhost6.localdomain6>
On Mon, 14 Mar 2011, Srikar Dronamraju wrote:
> +/*
> + * TODO:
> + * - Where necessary, examine the modrm byte and allow only valid instructions
> + * in the different Groups and fpu instructions.
> + */
> +
> +static bool is_prefix_bad(struct insn *insn)
> +{
> + int i;
> +
> + for (i = 0; i < insn->prefixes.nbytes; i++) {
> + switch (insn->prefixes.bytes[i]) {
> + case 0x26: /*INAT_PFX_ES */
> + case 0x2E: /*INAT_PFX_CS */
> + case 0x36: /*INAT_PFX_DS */
> + case 0x3E: /*INAT_PFX_SS */
> + case 0xF0: /*INAT_PFX_LOCK */
> + return 1;
true
> + }
> + }
> + return 0;
false
> +}
> +static int validate_insn_32bits(struct uprobe *uprobe, struct insn *insn)
> +{
> + insn_init(insn, uprobe->insn, false);
> +
> + /* Skip good instruction prefixes; reject "bad" ones. */
> + insn_get_opcode(insn);
> + if (is_prefix_bad(insn)) {
> + report_bad_prefix();
> + return -EPERM;
-ENOTSUPP perhaps. That's not a permission problem
> + }
> +/**
> + * analyze_insn - instruction analysis including validity and fixups.
> + * @tsk: the probed task.
> + * @uprobe: the probepoint information.
> + * Return 0 on success or a -ve number on error.
> + */
> +int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe)
> +{
> + int ret;
> + struct insn insn;
> +
> + uprobe->fixups = 0;
> +#ifdef CONFIG_X86_64
> + uprobe->arch_info.rip_rela_target_address = 0x0;
> +#endif
Please get rid of this #ifdef and use inlines (empty for 32bit)
> +
> + if (is_32bit_app(tsk))
> + ret = validate_insn_32bits(uprobe, &insn);
> + else
> + ret = validate_insn_64bits(uprobe, &insn);
> + if (ret != 0)
> + return ret;
> +#ifdef CONFIG_X86_64
Ditto
> + ret = handle_riprel_insn(uprobe, &insn);
> + if (ret == -1)
> + /* rip-relative; can't XOL */
> + return 0;
So we return -1 from handle_riprel_insn() and return success? Btw how
deals handle_riprel_insn() with 32bit user space ?
> +#endif
> + prepare_fixups(uprobe, &insn);
> + return 0;
Thanks,
tglx