[PATCH] [Karmic] SRU: arm: fix singal restart when Old EABI enabled

[Stefan Bader]

Eric Miao wrote:
> Stefan,
> 
> This patch is verified to fix bug #453682 for Karmic on dove, although not yet
> hit -stable.

It also does not have hit upstream as well. While for arm I think we could
go ahead of stable, I would prefer to have it upstream, so I can add that
commit id as reference.

> From 09f30d75269669eca5706fe2105196ee2f2c744c Mon Sep 17 00:00:00 2001
> From: Russle King <rmk+kernel at arm.linux.org.uk>
> Date: Tue, 27 Oct 2009 11:02:16 +0200
> Subject: [PATCH] arm: fix singal restart when Old EABI enabled
> 
<please add some description here>

CC: stable at kernel.org
> Signed-off-by: Saeed Bishara <saeed at marvell.com>
> ---
>  arch/arm/kernel/signal.c |   41 +++++++++++++++++------------------------
>  arch/arm/kernel/signal.h |    4 +++-
>  arch/arm/kernel/traps.c  |    4 +++-
>  3 files changed, 23 insertions(+), 26 deletions(-)
>  mode change 100644 => 100755 arch/arm/kernel/signal.c
> 
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> old mode 100644
> new mode 100755
> index f6bc5d4..b09af17
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -1,7 +1,7 @@
>  /*
>   *  linux/arch/arm/kernel/signal.c
>   *
> - *  Copyright (C) 1995-2002 Russell King
> + *  Copyright (C) 1995-2009 Russell King
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 as
> @@ -28,6 +28,7 @@
>   */
>  #define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
>  #define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
> +#define SWI_SYS_RESTART		(0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)

This is just minor nitpick, but is there a specific reason that this definition
does not use the same layout as the definitions above?

>  /*
>   * With EABI, the syscall number has to be loaded into r7.
> @@ -50,6 +51,18 @@ const unsigned long sigreturn_codes[7] = {
>  static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
> 
>  /*
> + * Either we support OABI only, or we have EABI with the OABI
> + * compat layer enabled.  In the later case we don't know if
> + * user space is EABI or not, and if not we must not clobber r7.
> + * Always using the OABI syscall solves that issue and works for
> + * all those cases.
> + */
> +const unsigned long syscall_restart_code[2] = {
> +	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
> +	0xe49df004,		/* ldr	pc, [sp], #4 */
> +};
> +
> +/*
>   * atomically swap in the new signal mask, and wait for a signal.
>   */
>  asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask,
> old_sigset_t mask, struct pt_regs *regs)
> @@ -663,32 +676,12 @@ static int do_signal(sigset_t *oldset, struct
> pt_regs *regs, int syscall)
>  				regs->ARM_pc -= 4;
>  #else
>  				u32 __user *usp;
> -				u32 swival = __NR_restart_syscall;
> 
> -				regs->ARM_sp -= 12;
> +				regs->ARM_sp -= 4;
>  				usp = (u32 __user *)regs->ARM_sp;
> 
> -				/*
> -				 * Either we supports OABI only, or we have
> -				 * EABI with the OABI compat layer enabled.
> -				 * In the later case we don't know if user
> -				 * space is EABI or not, and if not we must
> -				 * not clobber r7.  Always using the OABI
> -				 * syscall solves that issue and works for
> -				 * all those cases.
> -				 */
> -				swival = swival - __NR_SYSCALL_BASE + __NR_OABI_SYSCALL_BASE;
> -
> -				put_user(regs->ARM_pc, &usp[0]);
> -				/* swi __NR_restart_syscall */
> -				put_user(0xef000000 | swival, &usp[1]);
> -				/* ldr	pc, [sp], #12 */
> -				put_user(0xe49df00c, &usp[2]);
> -
> -				flush_icache_range((unsigned long)usp,
> -						   (unsigned long)(usp + 3));
> -
> -				regs->ARM_pc = regs->ARM_sp + 4;
> +				put_user(regs->ARM_pc, usp);
> +				regs->ARM_pc = KERN_RESTART_CODE;
>  #endif
>  			}
>  		}
> diff --git a/arch/arm/kernel/signal.h b/arch/arm/kernel/signal.h
> index 27beece..6fcfe83 100644
> --- a/arch/arm/kernel/signal.h
> +++ b/arch/arm/kernel/signal.h
> @@ -1,12 +1,14 @@
>  /*
>   *  linux/arch/arm/kernel/signal.h
>   *
> - *  Copyright (C) 2005 Russell King.
> + *  Copyright (C) 2005-2009 Russell King.
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 as
>   * published by the Free Software Foundation.
>   */
>  #define KERN_SIGRETURN_CODE	(CONFIG_VECTORS_BASE + 0x00000500)
> +#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
> 
>  extern const unsigned long sigreturn_codes[7];
> +extern const unsigned long syscall_restart_code[2];
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 57eb0f6..9cc19c9 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -1,7 +1,7 @@
>  /*
>   *  linux/arch/arm/kernel/traps.c
>   *
> - *  Copyright (C) 1995-2002 Russell King
> + *  Copyright (C) 1995-2009 Russell King
>   *  Fragments that appear the same as linux/arch/i386/kernel/traps.c
> (C) Linus Torvalds
>   *
>   * This program is free software; you can redistribute it and/or modify
> @@ -742,6 +742,8 @@ void __init early_trap_init(void)
>  	 */
>  	memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
>  	       sizeof(sigreturn_codes));
> +	memcpy((void *)KERN_RESTART_CODE, syscall_restart_code,
> +	       sizeof(syscall_restart_code));
> 
>  	flush_icache_range(vectors, vectors + PAGE_SIZE);
>  	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);

-Stefan