Re: [Qemu-devel] [PATCH] linux-user: Fix syscall instruction usermode emulation on X86_64

[Richard Henderson <rth@twiddle.net>]

On 08/07/2014 05:56 PM, Jincheng Miao wrote:
> Currently syscall instruction is buggy on user mode X86_64,
> the EIP is updated after do_syscall(), that is too late for
> clone(). Because clone() will create a thread at the env->EIP
> (the address of syscall insn), and then child thread enters
> do_syscall() again, that is not expected. Sometimes it is tragic.
> 
> User mode syscall insn emulation is not used MSR, so the
> action should be same to INT 0x80. INT 0x80 will update EIP in
> do_interrupt(), ditto for syscall() for consistency.
> 
> Signed-off-by: Jincheng Miao <jmiao@redhat.com>
> ---
>  linux-user/main.c        |    1 -
>  target-i386/seg_helper.c |    4 ++--
>  2 files changed, 2 insertions(+), 3 deletions(-)

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~