Re: [PATCH for-5.2 1/3] linux-user/sparc: Fix errors in target_ucontext structures

[LemonBoy <thatlemon@gmail.com>]

Hello Laurent,
you probably want to also apply my patch for stack_t definitions [1] that
was mentioned in Peter Maydell's cover letter for the patch series.

[1] https://patchew.org/QEMU/e9d47692-ee92-009f-6007-0abc3f502b97@gmail.com/

On 10/11/20 07:53, Laurent Vivier wrote:
> Le 05/11/2020 à 22:23, Peter Maydell a écrit :
>> The various structs that make up the SPARC target_ucontext had some
>> errors:
>>  * target structures must not include fields which are host pointers,
>>    which might be the wrong size.  These should be abi_ulong instead
>>  * because we don't have the 'long double' part of the mcfpu_fregs
>>    union in our version of the target_mc_fpu struct, we need to
>>    manually force it to be 16-aligned
>>
>> In particular, the lack of 16-alignment caused sparc64_get_context()
>> and sparc64_set_context() to read and write all the registers at the
>> wrong offset, which triggered a guest glibc stack check in
>> siglongjmp:
>>   *** longjmp causes uninitialized stack frame ***: terminated
>> when trying to run bash.
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>  linux-user/sparc/signal.c | 13 +++++++++----
>>  1 file changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/linux-user/sparc/signal.c b/linux-user/sparc/signal.c
>> index d796f50f665..57ea1593bfc 100644
>> --- a/linux-user/sparc/signal.c
>> +++ b/linux-user/sparc/signal.c
>> @@ -349,10 +349,15 @@ typedef abi_ulong target_mc_greg_t;
>>  typedef target_mc_greg_t target_mc_gregset_t[SPARC_MC_NGREG];
>>  
>>  struct target_mc_fq {
>> -    abi_ulong *mcfq_addr;
>> +    abi_ulong mcfq_addr;
>>      uint32_t mcfq_insn;
>>  };
>>  
>> +/*
>> + * Note the manual 16-alignment; the kernel gets this because it
>> + * includes a "long double qregs[16]" in the mcpu_fregs union,
>> + * which we can't do.
>> + */
>>  struct target_mc_fpu {
>>      union {
>>          uint32_t sregs[32];
>> @@ -362,11 +367,11 @@ struct target_mc_fpu {
>>      abi_ulong mcfpu_fsr;
>>      abi_ulong mcfpu_fprs;
>>      abi_ulong mcfpu_gsr;
>> -    struct target_mc_fq *mcfpu_fq;
>> +    abi_ulong mcfpu_fq;
>>      unsigned char mcfpu_qcnt;
>>      unsigned char mcfpu_qentsz;
>>      unsigned char mcfpu_enab;
>> -};
>> +} __attribute__((aligned(16)));
>>  typedef struct target_mc_fpu target_mc_fpu_t;
>>  
>>  typedef struct {
>> @@ -377,7 +382,7 @@ typedef struct {
>>  } target_mcontext_t;
>>  
>>  struct target_ucontext {
>> -    struct target_ucontext *tuc_link;
>> +    abi_ulong tuc_link;
>>      abi_ulong tuc_flags;
>>      target_sigset_t tuc_sigmask;
>>      target_mcontext_t tuc_mcontext;
>>
> 
> Applied to my linux-user-for-5.2 branch.
> 
> Thanks,
> Laurent
>