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Re: [PATCH 3/3] linux-user/i386: Emulate x86_64 vsyscalls
From: |
Richard Henderson |
Subject: |
Re: [PATCH 3/3] linux-user/i386: Emulate x86_64 vsyscalls |
Date: |
Thu, 16 Jan 2020 08:19:49 -1000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 |
On 1/16/20 6:26 AM, Alex Bennée wrote:
>> + /*
>> + * Perform the syscall. None of the vsyscalls should need restarting,
>> + * and all faults should have been caught above.
>> + */
>> + ret = do_syscall(env, syscall, env->regs[R_EDI], env->regs[R_ESI],
>> + env->regs[R_EDX], env->regs[10], env->regs[8],
>> + env->regs[9], 0, 0);
>
> How come the register ABI to the syscall is different to the others. I
> can see why syscall doesn't come from EAX but the others are a different
> set to normal syscalls which might be why:
Cut and paste error, I assume.
That said, the three syscalls have a maximum of 2 arguments,
so I could really just pass EDI and ESI and 0 for the rest...
> I'm seeing a EFAULT on the gettimeofday failure:
What getttimeofday failure? Is this related to the mention of /sbin/ldconfig
in your previous message?
> #0 do_syscall (cpu_env=cpu_env@entry=0x5555577d2b10, num=num@entry=96,
> arg1=0, arg2=0, arg3=4211016, arg4=8, arg5=274888677184, arg6=274886295415,
> arg7=0, arg8=0) at /home/alex/lsrc/qemu.git/linux-user/syscall.c:12076
>
> #1 0x0000555555609b6e in emulate_vsyscall (env=0x5555577d2b10) at
> /home/alex/lsrc/qemu.git/linux-user/x86_64/../i386/cpu_loop.c:180
> #2 cpu_loop (env=0x5555577d2b10) at
> /home/alex/lsrc/qemu.git/linux-user/x86_64/../i386/cpu_loop.c:246
>
> #3 0x000055555559640e in main (argc=<optimized out>, argv=<optimized
> #out>, envp=<optimized out>) at
> #/home/alex/lsrc/qemu.git/linux-user/main.c:865
>
> arg1/arg2 don't seem right here.
Why? NULL value for arg1 is legal, though semi-useless.
Ah, I see that our implementation of gettimeofday doesn't honor NULL.
r~
- [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Richard Henderson, 2020/01/14
- Re: [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Paolo Bonzini, 2020/01/14
- Re: [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Laurent Desnogues, 2020/01/15
- Re: [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Laurent Vivier, 2020/01/15
- Re: [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Alex Bennée, 2020/01/16
- Re: [PATCH 0/3] linux-user: Implement x86_64 vsyscalls, Alex Bennée, 2020/01/16