Re: [PATCH] x86/irq: Preserve vector in orig_ax for APIC code

[Alexander Graf <graf@amazon.com>]

On 26.08.20 15:22, Josh Poimboeuf wrote:
> 
> On Wed, Aug 26, 2020 at 01:53:57PM +0200, Alexander Graf wrote:
>> -.macro idtentry_body cfunc has_error_code:req
>> +.macro idtentry_body cfunc has_error_code:req preserve_error_code:req
>>
>>        call    error_entry
>>        UNWIND_HINT_REGS
>> @@ -328,7 +328,9 @@ SYM_CODE_END(ret_from_fork)
>>
>>        .if \has_error_code == 1
>>                movq    ORIG_RAX(%rsp), %rsi    /* get error code into 2nd argument*/
>> -             movq    $-1, ORIG_RAX(%rsp)     /* no syscall to restart */
>> +             .if \preserve_error_code == 0
>> +                     movq    $-1, ORIG_RAX(%rsp)     /* no syscall to restart */
>> +             .endif
> 
> When does this happen (has_error_code=1 && preserve_error_code=0)?  I
> don't see any users of this macro (or idtentry) with this combination.

It's well hidden in arch/x86/include/asm/idtentry.h:

#define DECLARE_IDTENTRY_ERRORCODE(vector, func)                        \
         idtentry vector asm_##func func has_error_code=1

/* Simple exception entries with error code pushed by hardware */
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_TS, exc_invalid_tss);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_NP, exc_segment_not_present);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS, exc_stack_segment);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP, exc_general_protection);
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC, exc_alignment_check);
[...]
DECLARE_IDTENTRY_RAW_ERRORCODE(X86_TRAP_PF,     exc_page_fault);


Alex



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879