On Sun, Jun 24, 2018 at 03:42:19PM +0200, Ard Biesheuvel wrote:
> Considering we had other weird issues involving uint64_t types with
> the TPM code just this week, I wonder if this isn't a fundamental
> problem with the mixed mode thunking, and so I need some help from the
> x86 gurus (Ingo?)
Looks like that's exactly what it does:
/*
* Convert x86-64 ABI params to i386 ABI
*/
subq $32, %rsp
movl %esi, 0x0(%rsp)
movl %edx, 0x4(%rsp)
movl %ecx, 0x8(%rsp)
movq %r8, %rsi
movl %esi, 0xc(%rsp)
movq %r9, %rsi
movl %esi, 0x10(%rsp)
I don't think there's a way to find out in thunk_64.S if the register
was populated with a 64-bit or 32-bit value, but it *might* be possible
to do it with a macro that accepts a __VA_ARGS__ argument, iterates
over the parameters, checks whether a parameter is 64-bit and we're
in mixed mode, and if so, passes in the high and low dword separately.
Lukas
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