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Date: Tue, 01 Apr 2014 12:21:37 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Ingo Molnar <mingo@...e.hu>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
David Long <dave.long@...aro.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
"Frank Ch. Eigler" <fche@...hat.com>,
Jim Keniston <jkenisto@...ibm.com>,
Jonathan Lebon <jlebon@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] uprobes/x86: Gather "riprel" functions together
(2014/04/01 4:44), Oleg Nesterov wrote:
> Cosmetic. Move pre_xol_rip_insn() and handle_riprel_post_xol() up
> to the closely related handle_riprel_insn().
>
> This way it is simpler to read and understand this code, and this
> lessens the number of ifdef's.
>
> TODO: rename them somehow to make the naming consistent.
>
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Looks good to me:)
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Thank you,
> ---
> arch/x86/kernel/uprobes.c | 118 ++++++++++++++++++++-------------------------
> 1 files changed, 53 insertions(+), 65 deletions(-)
>
> diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> index 382a69d..e8d7b38 100644
> --- a/arch/x86/kernel/uprobes.c
> +++ b/arch/x86/kernel/uprobes.c
> @@ -313,6 +313,48 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
> }
> }
>
> +/*
> + * If we're emulating a rip-relative instruction, save the contents
> + * of the scratch register and store the target address in that register.
> + */
> +static void
> +pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
> + struct arch_uprobe_task *autask)
> +{
> + if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
> + autask->saved_scratch_register = regs->ax;
> + regs->ax = current->utask->vaddr;
> + regs->ax += auprobe->rip_rela_target_address;
> + } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
> + autask->saved_scratch_register = regs->cx;
> + regs->cx = current->utask->vaddr;
> + regs->cx += auprobe->rip_rela_target_address;
> + }
> +}
> +
> +static void
> +handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
> +{
> + if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
> + struct arch_uprobe_task *autask;
> +
> + autask = ¤t->utask->autask;
> + if (auprobe->fixups & UPROBE_FIX_RIP_AX)
> + regs->ax = autask->saved_scratch_register;
> + else
> + regs->cx = autask->saved_scratch_register;
> +
> + /*
> + * The original instruction includes a displacement, and so
> + * is 4 bytes longer than what we've just single-stepped.
> + * Fall through to handle stuff like "jmpq *...(%rip)" and
> + * "callq *...(%rip)".
> + */
> + if (correction)
> + *correction += 4;
> + }
> +}
> +
> static int validate_insn_64bits(struct arch_uprobe *auprobe, struct insn *insn)
> {
> insn_init(insn, auprobe->insn, true);
> @@ -339,9 +381,19 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
> return validate_insn_64bits(auprobe, insn);
> }
> #else /* 32-bit: */
> +/*
> + * No RIP-relative addressing on 32-bit
> + */
> static void handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
> {
> - /* No RIP-relative addressing on 32-bit */
> +}
> +static void pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
> + struct arch_uprobe_task *autask)
> +{
> +}
> +static void handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs,
> + long *correction)
> +{
> }
>
> static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
> @@ -413,34 +465,6 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
> return 0;
> }
>
> -#ifdef CONFIG_X86_64
> -/*
> - * If we're emulating a rip-relative instruction, save the contents
> - * of the scratch register and store the target address in that register.
> - */
> -static void
> -pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
> - struct arch_uprobe_task *autask)
> -{
> - if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
> - autask->saved_scratch_register = regs->ax;
> - regs->ax = current->utask->vaddr;
> - regs->ax += auprobe->rip_rela_target_address;
> - } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
> - autask->saved_scratch_register = regs->cx;
> - regs->cx = current->utask->vaddr;
> - regs->cx += auprobe->rip_rela_target_address;
> - }
> -}
> -#else
> -static void
> -pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
> - struct arch_uprobe_task *autask)
> -{
> - /* No RIP-relative addressing on 32-bit */
> -}
> -#endif
> -
> /*
> * arch_uprobe_pre_xol - prepare to execute out of line.
> * @auprobe: the probepoint information.
> @@ -490,42 +514,6 @@ static int adjust_ret_addr(unsigned long sp, long correction)
> return 0;
> }
>
> -#ifdef CONFIG_X86_64
> -static bool is_riprel_insn(struct arch_uprobe *auprobe)
> -{
> - return ((auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) != 0);
> -}
> -
> -static void
> -handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
> -{
> - if (is_riprel_insn(auprobe)) {
> - struct arch_uprobe_task *autask;
> -
> - autask = ¤t->utask->autask;
> - if (auprobe->fixups & UPROBE_FIX_RIP_AX)
> - regs->ax = autask->saved_scratch_register;
> - else
> - regs->cx = autask->saved_scratch_register;
> -
> - /*
> - * The original instruction includes a displacement, and so
> - * is 4 bytes longer than what we've just single-stepped.
> - * Fall through to handle stuff like "jmpq *...(%rip)" and
> - * "callq *...(%rip)".
> - */
> - if (correction)
> - *correction += 4;
> - }
> -}
> -#else
> -static void
> -handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
> -{
> - /* No RIP-relative addressing on 32-bit */
> -}
> -#endif
> -
> /*
> * If xol insn itself traps and generates a signal(Say,
> * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped
>
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com
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