Re: [Qemu-devel] [PATCH] cpu-exec(): also reload CPUClass *cc after longjmp return

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2013-10-03 18:05, Peter Maydell wrote:
> On 3 October 2013 23:09, Juergen Lock <qemu-l@jelal.kn-bremen.de> wrote:
>> Local variable CPUClass *cc needs to be reloaded after return from longjmp
>> too.  (This fixes the mips-softmmu crash observed on FreeBSD when qemu is
>> built with clang.)
>>
>> Signed-off-by: Juergen Lock <nox@jelal.kn-bremen.de>
>> Found-by: Dimitry Andric <dim@FreeBSD.org>
>>
>> --- a/cpu-exec.c
>> +++ b/cpu-exec.c
>> @@ -681,6 +681,10 @@ int cpu_exec(CPUArchState *env)
>>               * local variables as longjmp is marked 'noreturn'. */
>>              cpu = current_cpu;
>>              env = cpu->env_ptr;
>> +#if !(defined(CONFIG_USER_ONLY) && \
>> +      (defined(TARGET_M68K) || defined(TARGET_PPC) || defined(TARGET_S390X)))
>> +            cc = CPU_GET_CLASS(cpu);
>> +#endif
> 
> This is a c compiler or libc bug -- the C standard says that this
> local variable should not be trashed by the longjmp. We were
> actually discussing removing the current workarounds there...

But we didn't decide if we should stop supporting the affected compiler
versions.

Does this issue also exist with the latest clang version available for
your platform?

Jan

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