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Re: [PATCH] MIPS: Fix syscall_get_nr for the syscall exit tracing.

To: Lars Persson <lars.persson@axis.com>, <linux-mips@linux-mips.org>, <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: Fix syscall_get_nr for the syscall exit tracing.
From: Markos Chandras <Markos.Chandras@imgtec.com>
Date: Thu, 12 Feb 2015 14:26:33 +0000
Cc: Lars Persson <larper@axis.com>
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On 02/03/2015 04:08 PM, Lars Persson wrote:
> Register 2 is alredy overwritten by the return value when
> syscall_trace_leave() is called.
> 
> Signed-off-by: Lars Persson <larper@axis.com>
> ---
>  arch/mips/include/asm/syscall.h     |    8 +-------
>  arch/mips/include/asm/thread_info.h |    1 +
>  arch/mips/kernel/ptrace.c           |    2 ++
>  3 files changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
> index bb79637..6499d93 100644
> --- a/arch/mips/include/asm/syscall.h
> +++ b/arch/mips/include/asm/syscall.h
> @@ -29,13 +29,7 @@
>  static inline long syscall_get_nr(struct task_struct *task,
>                                 struct pt_regs *regs)
>  {
> -     /* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
> -     if ((config_enabled(CONFIG_32BIT) ||
> -         test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
> -         (regs->regs[2] == __NR_syscall))
> -             return regs->regs[4];
> -     else
> -             return regs->regs[2];
> +     return current_thread_info()->syscall;
>  }
>  
>  static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
> diff --git a/arch/mips/include/asm/thread_info.h 
> b/arch/mips/include/asm/thread_info.h
> index 99eea59..e4440f9 100644
> --- a/arch/mips/include/asm/thread_info.h
> +++ b/arch/mips/include/asm/thread_info.h
> @@ -36,6 +36,7 @@ struct thread_info {
>                                                */
>       struct restart_block    restart_block;
>       struct pt_regs          *regs;
> +     long                    syscall;        /* syscall number */
>  };
>  
>  /*
> diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
> index 9d1487d..5104528 100644
> --- a/arch/mips/kernel/ptrace.c
> +++ b/arch/mips/kernel/ptrace.c
> @@ -770,6 +770,8 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, 
> long syscall)
>       long ret = 0;
>       user_exit();
>  
> +     current_thread_info()->syscall = syscall;
> +
>       if (secure_computing() == -1)
>               return -1;
>  
> 

Hi,

This is now in mainline but parts of it can apply to stable as well?
Would you be willing to send a backported version for the stable trees?
Thanks a lot

-- 
markos

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