9 May
2019
9 May
'19
5:18 p.m.
On Thu, May 09, 2019 at 09:20:06AM -0700, Andy Lutomirski wrote:
+ENTRY(call_to_exception_trampoline)
- /*
* On entry the stack looks like:** 2*4(%esp) <previous context>* 1*4(%esp) RET-IP* 0*4(%esp) func** transform this into:** 19*4(%esp) <previous context>* 18*4(%esp) gap / RET-IP* 17*4(%esp) gap / func* 16*4(%esp) ss* 15*4(%esp) sp / <previous context>* 14*4(%esp) flags* 13*4(%esp) cs* 12*4(%esp) ip / RET-IP* 11*4(%esp) orig_eax* 10*4(%esp) gs* 9*4(%esp) fs* 8*4(%esp) es* 7*4(%esp) ds* 6*4(%esp) eax* 5*4(%esp) ebp* 4*4(%esp) edi* 3*4(%esp) esi* 2*4(%esp) edx* 1*4(%esp) ecx* 0*4(%esp) ebx*/- pushl %ss
- pushl %esp # points at ss
- addl $3*4, (%esp) # point it at <previous context>
- pushfl
- pushl %cs
- pushl 5*4(%esp) # RET-IP
- subl 5, (%esp) # point at CALL instruction
- pushl $-1
- pushl %gs
- pushl %fs
- pushl %es
- pushl %ds
- pushl %eax
- pushl %ebp
- pushl %edi
- pushl %esi
- pushl %edx
- pushl %ecx
- pushl %ebx
- ENCODE_FRAME_POINTER
- movl %esp, %eax # 1st argument: pt_regs
- movl 17*4(%esp), %ebx # func
- CALL_NOSPEC %ebx
- movl PT_OLDESP(%esp), %eax
- movl PT_EIP(%esp), %ecx
- movl %ecx, -1*4(%eax)
- movl PT_EFLAGS(%esp), %ecx
- movl %ecx, -2*4(%eax)
- movl PT_EAX(%esp), %ecx
- movl %ecx, -3*4(%eax)
- popl %ebx
- popl %ecx
- popl %edx
- popl %esi
- popl %edi
- popl %ebp
- lea -3*4(%eax), %esp
- popl %eax
- popfl
- ret
+END(call_to_exception_trampoline)
Potentially minor nit: you’re doing popfl, but you’re not doing TRACE_IRQ_whatever. This makes me think that you should either add the tracing (ugh!) or you should maybe just skip the popfl.
Yeah, so we really should not change flags I suppose. If this lives I'll remove the popfl.