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Date: Tue, 2 Feb 2010 23:35:42 -0500
From: Matt Turner <mattst88@...il.com>
To: Christoph Hellwig <hch@....de>
Cc: roland@...hat.com, oleg@...hat.com, akpm@...ux-foundation.org,
ink@...assic.park.msu.ru, rth@...ddle.net,
linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 2/14] alpha: use generic ptrace_resume code
On Tue, Feb 2, 2010 at 1:58 PM, Christoph Hellwig <hch@....de> wrote:
> Use the generic ptrace_resume code for PTRACE_SYSCALL, PTRACE_CONT,
> PTRACE_KILL and PTRACE_SINGLESTEP. This implies defining
> arch_has_single_step in <asm/ptrace.h> and implementing the
> user_enable_single_step and user_disable_single_step functions, which
> also causes the breakpoint information to be cleared on fork, which
> could be considered a bug fix.
>
> Also the TIF_SYSCALL_TRACE thread flag is now cleared on PTRACE_KILL
> which it previously wasn't, which is consistent with all architectures
> using the modern ptrace code.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
>
> Index: linux-2.6/arch/alpha/kernel/ptrace.c
> ===================================================================
> --- linux-2.6.orig/arch/alpha/kernel/ptrace.c 2010-02-02 11:05:03.197004058 +0100
> +++ linux-2.6/arch/alpha/kernel/ptrace.c 2010-02-02 11:07:04.091006019 +0100
> @@ -249,6 +249,17 @@ ptrace_cancel_bpt(struct task_struct * c
> return (nsaved != 0);
> }
>
> +void user_enable_single_step(struct task_struct *child)
> +{
> + /* Mark single stepping. */
> + task_thread_info(child)->bpt_nsaved = -1;
> +}
> +
> +void user_disable_single_step(struct task_struct *child)
> +{
> + ptrace_cancel_bpt(child);
> +}
> +
> /*
> * Called by kernel/ptrace.c when detaching..
> *
> @@ -256,7 +267,7 @@ ptrace_cancel_bpt(struct task_struct * c
> */
> void ptrace_disable(struct task_struct *child)
> {
> - ptrace_cancel_bpt(child);
> + user_disable_single_step(child);
> }
>
> long arch_ptrace(struct task_struct *child, long request, long addr, long data)
> @@ -289,52 +300,6 @@ long arch_ptrace(struct task_struct *chi
> DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
> ret = put_reg(child, addr, data);
> break;
> -
> - case PTRACE_SYSCALL:
> - /* continue and stop at next (return from) syscall */
> - case PTRACE_CONT: /* restart after signal. */
> - ret = -EIO;
> - if (!valid_signal(data))
> - break;
> - if (request == PTRACE_SYSCALL)
> - set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
> - else
> - clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
> - child->exit_code = data;
> - /* make sure single-step breakpoint is gone. */
> - ptrace_cancel_bpt(child);
> - wake_up_process(child);
> - ret = 0;
> - break;
> -
> - /*
> - * Make the child exit. Best I can do is send it a sigkill.
> - * perhaps it should be put in the status that it wants to
> - * exit.
> - */
> - case PTRACE_KILL:
> - ret = 0;
> - if (child->exit_state == EXIT_ZOMBIE)
> - break;
> - child->exit_code = SIGKILL;
> - /* make sure single-step breakpoint is gone. */
> - ptrace_cancel_bpt(child);
> - wake_up_process(child);
> - break;
> -
> - case PTRACE_SINGLESTEP: /* execute single instruction. */
> - ret = -EIO;
> - if (!valid_signal(data))
> - break;
> - /* Mark single stepping. */
> - task_thread_info(child)->bpt_nsaved = -1;
> - clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
> - child->exit_code = data;
> - wake_up_process(child);
> - /* give it a chance to run. */
> - ret = 0;
> - break;
> -
> default:
> ret = ptrace_request(child, request, addr, data);
> break;
> Index: linux-2.6/arch/alpha/include/asm/ptrace.h
> ===================================================================
> --- linux-2.6.orig/arch/alpha/include/asm/ptrace.h 2010-02-02 11:07:29.091023600 +0100
> +++ linux-2.6/arch/alpha/include/asm/ptrace.h 2010-02-02 11:07:38.645007248 +0100
> @@ -68,6 +68,7 @@ struct switch_stack {
>
> #ifdef __KERNEL__
>
> +#define arch_has_single_step() (1)
> #define user_mode(regs) (((regs)->ps & 8) != 0)
> #define instruction_pointer(regs) ((regs)->pc)
> #define profile_pc(regs) instruction_pointer(regs)
>
Acked-by: Matt Turner <mattst88@...il.com>
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