On 9/26/2018 5:05 PM, Laszlo Ersek wrote:
Hi,
On 09/25/18 21:48, Laszlo Ersek wrote:
Currently, "gcc-4.8.5-28.el7_5.1.x86_64" generates the following code for
me, from the XADD inline assembly added to "X64/GccInline.c" in commit
17634d026f96:
0000000000004383 <InternalSyncIncrement>:
UINT32
EFIAPI
InternalSyncIncrement (
IN volatile UINT32 *Value
)
{
4383: 55 push %rbp
4384: 48 89 e5 mov %rsp,%rbp
4387: 48 83 ec 10 sub $0x10,%rsp
438b: 48 89 4d 10 mov %rcx,0x10(%rbp)
UINT32 Result;
__asm__ __volatile__ (
438f: 48 8b 55 10 mov 0x10(%rbp),%rdx
4393: 48 8b 45 10 mov 0x10(%rbp),%rax
4397: b8 01 00 00 00 mov $0x1,%eax
439c: f0 0f c1 00 lock xadd %eax,(%rax)
43a0: ff c0 inc %eax
43a2: 89 45 fc mov %eax,-0x4(%rbp)
: "m" (*Value) // %2
: "memory",
"cc"
);
return Result;
43a5: 8b 45 fc mov -0x4(%rbp),%eax
}
43a8: c9 leaveq
43a9: c3 retq
The MOV $0X1,%EAX instruction corrupts the address of Value in %RAX before
we reach the XADD instruction. In fact, it makes no sense for XADD to use
%EAX as source operand and (%RAX) as destination operand at the same time.
may I get a fast review for this patch, please? The regression from
commit 17634d026f96 prevents OVMF from booting.
Sure. Reviewed-by: Ruiyu Ni <[email protected]>
Thanks
Laszlo
--
Thanks,
Ray
_______________________________________________
edk2-devel mailing list
[email protected]
https://lists.01.org/mailman/listinfo/edk2-devel
