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

[Yufeng Zhang <Yufeng dot Zhang at arm dot com>]

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?

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.

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