Re: [PATCH v2] target/mips: Rewrite UHI errno_mips() using switch statement

[Philippe Mathieu-Daudé]

On 7/6/21 3:35 PM, Thomas Huth wrote:
> On 06/07/2021 15.07, Philippe Mathieu-Daudé wrote:
>> Linking on Haiku OS fails:
>>
>>   
>> /boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/8.3.0/../../../../x86_64-unknown-haiku/bin/ld:
>>
>>    error:
>> libqemu-mips-softmmu.fa.p/target_mips_tcg_sysemu_mips-semi.c.o(.rodata) is
>> too large (0xffff405a bytes)
>>   
>> /boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/8.3.0/../../../../x86_64-unknown-haiku/bin/ld:
>>
>>    final link failed: memory exhausted
>>    collect2: error: ld returned 1 exit status
>>
>> This is because the host_to_mips_errno[] uses errno as index,
>> for example:
>>
>>    static const uint16_t host_to_mips_errno[] = {
>>        [ENAMETOOLONG] = 91,
>>        ...
>>
>> and Haiku defines [*] ENAMETOOLONG as:
>>
>>     12 /* Error baselines */
>>     13 #define B_GENERAL_ERROR_BASE              INT_MIN
>>     ..
>>     22 #define B_STORAGE_ERROR_BASE              (B_GENERAL_ERROR_BASE
>> + 0x6000)
>>    ...
>>    106 #define B_NAME_TOO_LONG                   (B_STORAGE_ERROR_BASE
>> + 4)
>>    ...
>>    211 #define ENAMETOOLONG                     
>> B_TO_POSIX_ERROR(B_NAME_TOO_LONG)
>>
>> so the array ends up beeing indeed too big.
>>
>> Since POSIX errno can't be use as indexes on Haiku,
>> rewrite errno_mips() using a switch statement.
>>
>> [*]
>> https://github.com/haiku/haiku/blob/r1beta3/headers/os/support/Errors.h#L130
>>
>>
>> Reported-by: Richard Zak <richard.j.zak@gmail.com>
>> Suggested-by: Thomas Huth <thuth@redhat.com>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>> Supersedes: <20210704170736.617895-4-f4bug@amsat.org>
>> ---
>>   target/mips/tcg/sysemu/mips-semi.c | 24 +++++++++---------------
>>   1 file changed, 9 insertions(+), 15 deletions(-)
>>
>> diff --git a/target/mips/tcg/sysemu/mips-semi.c
>> b/target/mips/tcg/sysemu/mips-semi.c
>> index 77108b0b1a9..b4a383ae90c 100644
>> --- a/target/mips/tcg/sysemu/mips-semi.c
>> +++ b/target/mips/tcg/sysemu/mips-semi.c
>> @@ -74,25 +74,19 @@ enum UHIOpenFlags {
>>       UHIOpen_EXCL   = 0x800
>>   };
>>   -/* Errno values taken from asm-mips/errno.h */
>> -static const uint16_t host_to_mips_errno[] = {
>> -    [ENAMETOOLONG] = 78,
>> +static int errno_mips(int host_errno)
>> +{
>> +    /* Errno values taken from asm-mips/errno.h */
>> +    switch (host_errno) {
>> +    case 0:             return 0;
>> +    case ENAMETOOLONG:  return 78;
>>   #ifdef EOVERFLOW
>> -    [EOVERFLOW]    = 79,
>> +    case EOVERFLOW:     return 79;
>>   #endif
>>   #ifdef ELOOP
>> -    [ELOOP]        = 90,
>> +    case ELOOP:         return 90;
>>   #endif
>> -};
>> -
>> -static int errno_mips(int err)
>> -{
>> -    if (err < 0 || err >= ARRAY_SIZE(host_to_mips_errno)) {
>> -        return EINVAL;
>> -    } else if (host_to_mips_errno[err]) {
>> -        return host_to_mips_errno[err];
>> -    } else {
>> -        return err;
>> +    default:            return EINVAL;
>>       }
>>   }
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 
> I assume you'll do the number fixup (your previous "target/mips: Fix UHI
> error values" patch) on top of this now?

The semihosting errnos are incorrect since the feature got introduced,
so I suppose nobody really uses this code, and fixing it is not urgent.
Since soft-freeze is close, I prefer to simply unblock Richard build.

Thanks for the simple suggestion and review!

Phil.