On Thu, Dec 3, 2015 at 9:08 AM, Barret Rhoden <[email protected]> wrote:
> .text
> _alltraps:
> cld
> - swapgs # harmless if we were already in the kernel
> pushq %r15
> pushq %r14
> pushq %r13
> @@ -367,32 +366,14 @@ _alltraps:
> pushq %rbx
> pushq %rax
> cmpw $GD_KT, 0x90(%rsp) # 0x90 - diff btw tf_cs and tf_rax
>
Look at what Linux does for those magic offsets. They are auto-generated
from proper C structs.
This have the twofold advantage that changes to structure do not cause ASM
breakages, and they also have nice names, WRT magic numbers.
+ je trap_all_tf
> + # this is a user TF. we need to swapgs to get the kernel's gs and
> mark the
> + # context as partial
> + swapgs # user's GS is now in
> MSR_KERNEL_GS_BASE
> + movl $0x1, 0xac(%rsp) # 0xac - diff btw tf_padding0 and tf_rax
>
Ditto.
@@ -436,32 +416,14 @@ _allirqs:
> pushq %rbx
> pushq %rax
> cmpw $GD_KT, 0x90(%rsp) # 0x90 - diff btw tf_cs and tf_rax
>
Ditto.
+ # this is a user TF. we need to swapgs to get the kernel's gs and
> mark the
> + # context as partial
> + swapgs # user's GS is now in
> MSR_KERNEL_GS_BASE
> + movl $0x1, 0xac(%rsp) # 0xac - diff btw tf_padding0 and tf_rax
>
Ditto.
# cld is handled by the SFMASK
> - swapgs
> + swapgs # user's GS is now in
> MSR_KERNEL_GS_BASE
> movq %gs:0, %rsp
>
Ditto.
> # Saving the FPU callee-saved state for now. Might be able to
> have the
> # preempt handler deal with it.
> - pushq $0 # space for mxcsr and fpucw
> + pushq $0 # space for mxcsr, fpucw,
> and padding0
> + movw $0x1, 0x6(%rsp) # tf_padding0 = 1, partial context
>
Ditto.
--
You received this message because you are subscribed to the Google Groups
"Akaros" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
For more options, visit https://groups.google.com/d/optout.
