In-Reply-To: <200603222115.46926.ak@xxxxxxx>
On Wed, 22 Mar 2006 21:15:44 +0100, Andi Kleen wrote:
> On Monday 13 March 2006 19:02, Zachary Amsden wrote:
> > The VMI ROM detection and code patching mechanism is illustrated in
> > setup.c. There ROM is a binary block published by the hypervisor, and
> > and there are certainly implications of this. ROMs certainly have a
> > history of being proprietary, very differently licensed pieces of
> > software, and mostly under non-free licenses. Before jumping to the
> > conclusion that this is a bad thing, let us consider more carefully
> > why hiding the interface layer to the hypervisor is actually a good
> > thing.
>
> How about you fix all these issues you describe here first
> and then submit it again?
>
> The disassembly stuff indeed doesn't look like something
> that belongs in the kernel.
I think they put the disassembler in there as a joke. ;)
It's not necessary for fixing up the call site, anyway. Something like
this should work, assuming there is always a call in every vmi
translation.
/* Now, measure and emit the vmi translation sequence */
#define vmi_translation_start \
.pushsection .vmi.translation,"ax"; \
781:;
#define vmi_translation_finish \
- 782:; \
+ 783:; \
.popsection;
#define vmi_translation_begin 781b
-#define vmi_translation_end 782b
+#define vmi_call_location 782b
+#define vmi_translation_end 783b
#define vmi_translation_len (vmi_translation_end - vmi_translation_begin)
+#define vmi_call_offset (vmi_call_location - vmi_translation_begin)
#define vmi_call(name) \
- call .+5+name
+ 782: call .+5+name
#define vmi_annotate(name) \
.pushsection .vmi.annotation,"a"; \
.align 4; \
.long name; \
.long vmi_padded_begin; \
.long vmi_translation_begin; \
.byte vmi_padded_len; \
.byte vmi_translation_len; \
.byte vmi_pad_total; \
- .byte 0; \
+ .byte vmi_call_offset; \
.popsection;
struct vmi_annotation {
unsigned long vmi_call;
unsigned char *nativeEIP;
unsigned char *translationEIP;
unsigned char native_size;
unsigned char translation_size;
char nop_size;
- unsigned char pad;
+ unsigned char call_offset;
};
static void fixup_translation(struct vmi_annotation *a)
{
unsigned char *c, *start, *end;
int left;
memcpy(a->nativeEIP, a->translationEIP, a->translation_size);
+ patch_call_site(a, a->nativeEIP + a->call_offset);
- start = a->nativeEIP;
- end = a->nativeEIP + a->translation_size;
-
- for (c = start; c < end;) {
- switch(*c) {
- case MNEM_CALL_NEAR:
- patch_call_site(a, c);
- c+=5;
- break;
-
- case MNEM_PUSH_I:
- c+=5;
- break;
-
- case MNEM_PUSH_IB:
- c+=2;
- break;
-
- case MNEM_PUSH_EAX:
- case MNEM_PUSH_ECX:
- case MNEM_PUSH_EDX:
- case MNEM_PUSH_EBX:
- case MNEM_PUSH_EBP:
- case MNEM_PUSH_ESI:
- case MNEM_PUSH_EDI:
- c+=1;
- break;
-
- case MNEM_LEA:
- BUG_ON(*(c+1) != 0x64); /* [--][--]+disp8, %esp */
- BUG_ON(*(c+2) != 0x24); /* none + %esp */
- c+=4;
- break;
-
- default:
- /*
- * Don't printk - it may acquire spinlocks with
- * partially completed VMI translations, causing
- * nuclear meltdown of the core.
- */
- BUG();
- return;
- }
- }
--
Chuck
"Penguins don't come from next door, they come from the Antarctic!"
