Re: [PATCH, AArch64] Fix bug in hardware watchpoint/breakpoint handling

[pinskia at gmail dot com]

> On Dec 18, 2013, at 8:07 AM, Yufeng Zhang <Yufeng.Zhang@arm.com> wrote:
> 
> Hi,
> 
> This patch fixes an AArch64 GDB bug in handling the hardware debug registers.  GDB calls ptrace to set hardware debug registers and it passes a full-length "struct user_hwdebug_state" variable regardless of the number of hardware debug registers available on a target.  When there are fewer than 16 (the maximum number) hardware breakpoint/watchpoint registers on a target, the kernel will complain about the gdb's request to set non-existing hardware debug registers. There will be an warning of "Unexpected error setting hardware debug registers" when the inferior starts to run.
> 
> This patch fixes the issue by setting iov.iov_len with a value reflecting the exact size in use.
> 
> OK for the mainline?

I think this patch is wrong as the size that is passed is always just one element as sizeof (regs.dbg_regs [count - 1]) is the same as sizeof (regs.dbg_regs [0]). This should have been sizeof (regs.dbg_regs [0])*count instead. 

Thanks,
Andrew Pinski

> 
> Thanks.
> Yufeng
> 
> 
> gdb/
> 
>       * aarch64-linux-nat.c (aarch64_linux_set_debug_regs): Set
>   iov.iov_len with the real length in use.
> 
> gdb/gdbserver/
> 
>       * linux-aarch64-low.c (aarch64_linux_set_debug_regs): Set
>   iov.iov_len with the real length in use.
> <patch>