Re: [PATCH v3] mscoree: Implement VTable fixup for x86_64 architecture.

[Sebastian Lackner]

On 22.01.2016 23:24, Paul Gofman wrote:
> Signed-off-by: Paul Gofman
>
> dlls/mscoree/corruntimehost.c | 91 +++++++++++++++++++++++++++++++++++++------
>  1 file changed, 79 insertions(+), 12 deletions(-)
>
> diff --git a/dlls/mscoree/corruntimehost.c b/dlls/mscoree/corruntimehost.c
> index e437cc2..05ac9c9 100644
> --- a/dlls/mscoree/corruntimehost.c
> +++ b/dlls/mscoree/corruntimehost.c
> @@ -919,7 +919,68 @@ static const struct vtable_fixup_thunk thunk_template = {
>
> #include "poppack.h"
>
> -#else /* !defined(__i386__) */
> +#elif __x86_64__ /* !__i386__ */
> -
>
> +# define CAN_FIXUP_VTABLE 1
> -
>
> +#include "pshpack1.h"
> -
>
> +struct vtable_fixup_thunk
> +{
> - /* push %rcx; push %rdx; push %r8; push %r9 */

I think it would be better to allocate a proper stack frame (pushq %rbp, movq %rsp, %rbp, subq ...,%rsp)
and then use movq instructions.
> - BYTE i1[6];
> - /*  sub $0x68, %rsp ; 0x10*4 + 0x20 + 0x8 (align stack for subsequent func call)
> -
>    movups %xmm0,0x28(%esp); ...; movups %xmm5,0x58(%esp)

Shouldn't it be %rsp ? Same for the precompiled assembler code below.
Also, its theoretically safe to use movdqa like done in various other wine functions.
> -
> -
>    ReallyFixupVTable will crash if we are called with unaligned stack

There is no need to add a comment for that, its expected to crash when misaligning the stack.
> - */
> - BYTE i2[28];
> - /* mov function,%eax */
> - BYTE i3[2];
> - void (CDECL *function)(struct dll_fixup *);
> - /* mov fixup,%rcx */
> - BYTE i4[2];
> - struct dll_fixup *fixup;
> - /* call *%eax */
> - BYTE i5[2];
> - /*
> -
>    movups 0x28(%esp),xmm0; ...; movups 0x58(%esp),xmm3
> -
>    add $0x68, %rsp
> - */
> - BYTE i6[28];
> - /* pop %r9; pop %r8; pop %rdx; pop %rcx */
> - BYTE i7[6];
> - /* mov vtable_entry, %rax */
> - BYTE i8[2];
> - void *vtable_entry;
> - /* mov [%rax],%rax
> -
>   jmp %rax */
> - BYTE i9[5];
>
> +};
> -
>
> +static const struct vtable_fixup_thunk thunk_template = {
> - {0x51,0x52,0x41,0x50,0x41,0x51},
> - {0x48,0x83,0xEC,0x68,
> -
> 0x67,0x0F,0x11,0x44,0x24,0x28, 0x67,0x0F,0x11,0x4C,0x24,0x38,
> -
> 0x67,0x0F,0x11,0x54,0x24,0x48, 0x67,0x0F,0x11,0x5C,0x24,0x58,
> - },
> - {0x48,0xB8},
> - NULL,
> - {0x48,0xB9},
> - NULL,
> - {0xFF,0xD0},
> - {0x67,0x0F,0x10,0x44,0x24,0x28, 0x67,0x0F,0x10,0x4C,0x24,0x38,
> -
> 0x67,0x0F,0x10,0x54,0x24,0x48, 0x67,0x0F,0x10,0x5C,0x24,0x58,
> -
> 0x48,0x83,0xC4,0x68},
> - {0x41,0x59,0x41,0x58,0x5A,0x59},
> - {0x48,0xB8},
> - NULL,
> - {0x48,0x8B,0x00,0xFF,0xE0}
>
> +};
> -
>
> +#include "poppack.h"
> -
>
> +#else /* !__i386__ && !__x86_64__ */
>
> # define CAN_FIXUP_VTABLE 0
>
> @@ -982,15 +1043,19 @@ static void CDECL ReallyFixupVTable(struct dll_fixup *fixup)
>          /* Mono needs an image that belongs to an assembly. */
>          image = mono_assembly_get_image(assembly);
>
> +#if __x86_64__
> -
>    if (fixup->fixup->type & COR_VTABLE_64BIT)
>
> +#else
>          if (fixup->fixup->type & COR_VTABLE_32BIT)
> +#endif
>          {
> -
>        DWORD *vtable = fixup->vtable;
> -
>        DWORD *tokens = fixup->tokens;
> -
>        void **vtable = fixup->vtable;
> -
>        ULONG_PTR *tokens = fixup->tokens;
>        for (i=0; i<fixup->fixup->count; i++)
>        {
> -
>            TRACE("%x\n", tokens[i]);
> -
>            vtable[i] = PtrToUint(mono_marshal_get_vtfixup_ftnptr(
> -
>                image, tokens[i], fixup->fixup->type));
> -
>            TRACE("%#lx\n", tokens[i]);
> -
>            vtable[i] = mono_marshal_get_vtfixup_ftnptr(
> -
>                image, tokens[i], fixup->fixup->type);

I would suggest to move those changes and some of the changes below into a separate patch.
They can easily be reviewed separately and using PtrToUint() instead of pointer types wasn't
even a good idea on 32-bit. ;)
>          }
>      }
>
> @@ -1029,16 +1094,18 @@ static void FixupVTableEntry(HMODULE hmodule, VTableFixup *vtable_fixup)
>      fixup->vtable = (BYTE*)hmodule + vtable_fixup->rva;
>      fixup->done = FALSE;
> - TRACE("vtable_fixup->type=0x%x\n",vtable_fixup->type);
>
> +#if __x86_64__
> - if (vtable_fixup->type & COR_VTABLE_64BIT)
>
> +#else
>      if (vtable_fixup->type & COR_VTABLE_32BIT)
> +#endif
>      {
> -
>    DWORD *vtable = fixup->vtable;
> -
>    DWORD *tokens;
> -
>    void **vtable = fixup->vtable;
> -
>    ULONG_PTR *tokens;
>    int i;
>    struct vtable_fixup_thunk *thunks = fixup->thunk_code;
>
> -
>    if (sizeof(void*) > 4)
> -
>        ERR("32-bit fixup in 64-bit mode; broken image?\n");
> -
>    tokens = fixup->tokens = HeapAlloc(GetProcessHeap(), 0, sizeof(*tokens) * vtable_fixup->count);
>    memcpy(tokens, vtable, sizeof(*tokens) * vtable_fixup->count);
>    for (i=0; i<vtable_fixup->count; i++)
>
> @@ -1047,7 +1114,7 @@ static void FixupVTableEntry(HMODULE hmodule, VTableFixup *vtable_fixup)
>              thunks[i].fixup = fixup;
>              thunks[i].function = ReallyFixupVTable;
>              thunks[i].vtable_entry = &vtable[i];
> -
>        vtable[i] = PtrToUint(&thunks[i]);
> -
>        vtable[i] = &thunks[i];
>    }
> }
>    else