[PATCH] ARM: aout-core: zero thread debug registers in a.out core dump

[Bryan Wu]

On Tue, Mar 8, 2011 at 6:57 PM, Will Deacon <will.deacon at arm.com> wrote:
> The removal of the single-step emulation from ptrace on ARM means that
> thread_struct no longer has software breakpoint fields in its debug
> member.
>
> This patch fixes the a.out core dump code so that the debug registers
> are zeroed rather than trying to copy from non-existent fields.
>
> Cc: Nicolas Pitre <nicolas.pitre at linaro.org>
> Reported-by: Bryan Wu <bryan.wu at canonical.com>
> Signed-off-by: Will Deacon <will.deacon at arm.com>
> ---
>
> Hi Bryan,
>
> Feel free to upgrade your tag on this (signed-off / acked) since this is
> clearly based on the patch you posted yesterday. I'd like to get this to
> Russell ASAP so that we don't get a build-breaker in the near future.
>

Oh, I missed this email. Just send out an similar patch.

> Cheers,
>
> Will
>
>  arch/arm/include/asm/a.out-core.h |    6 +-----
>  arch/arm/include/asm/user.h       |    2 +-
>  2 files changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/include/asm/a.out-core.h b/arch/arm/include/asm/a.out-core.h
> index 93d04ac..92f10cb 100644
> --- a/arch/arm/include/asm/a.out-core.h
> +++ b/arch/arm/include/asm/a.out-core.h
> @@ -32,11 +32,7 @@ static inline void aout_dump_thread(struct pt_regs *regs, struct user *dump)
>        dump->u_dsize = (tsk->mm->brk - tsk->mm->start_data + PAGE_SIZE - 1) >> PAGE_SHIFT;
>        dump->u_ssize = 0;
>
> -       dump->u_debugreg[0] = tsk->thread.debug.bp[0].address;
> -       dump->u_debugreg[1] = tsk->thread.debug.bp[1].address;
> -       dump->u_debugreg[2] = tsk->thread.debug.bp[0].insn.arm;
> -       dump->u_debugreg[3] = tsk->thread.debug.bp[1].insn.arm;
> -       dump->u_debugreg[4] = tsk->thread.debug.nsaved;
> +       memset(dump->u_debugreg, 0, sizeof(dump->u_debugreg));
>
I think this should be
 memset(dump->u_debugreg, 0, sizeof(dump->u_debugreg) * 8);

u_debugreg is a pointer to a int, the array contains 8 of them as we
found in the user.h

>        if (dump->start_stack < 0x04000000)
>                dump->u_ssize = (0x04000000 - dump->start_stack) >> PAGE_SHIFT;
> diff --git a/arch/arm/include/asm/user.h b/arch/arm/include/asm/user.h
> index 05ac4b0..35917b3 100644
> --- a/arch/arm/include/asm/user.h
> +++ b/arch/arm/include/asm/user.h
> @@ -71,7 +71,7 @@ struct user{
>                                /* the registers. */
>   unsigned long magic;         /* To uniquely identify a core file */
>   char u_comm[32];             /* User command that was responsible */
> -  int u_debugreg[8];
> +  int u_debugreg[8];           /* No longer used */
>   struct user_fp u_fp;         /* FP state */
>   struct user_fp_struct * u_fp0;/* Used by gdb to help find the values for */
>                                /* the FP registers. */
> --
> 1.7.0.4
>
>
-Bryan